Interior Communications Electrician, Volume 1

Enhanced Performance Position Accuracy (EP2A)

(Refer to Figure 4-58) The EP2A feature of the INS addresses the residual errors that remain in the INS position solution. The INS errors are characteristically slowly varying; e.g., the 84.4-minute Schuler period and the 24-hour earth loop. In contrast, the errors in the GPS aiding source are short period, typically on the order of seconds to minutes, and are more random in nature; e.g., ionospheric and multipath errors. The INS uses EP2A to estimate the current value of the slowly varying INS error and to "average out" the short-period GPS errors to provide a Real-time estimate of the correction to the Kalman-derived INS position.

(O) Organizational

(Shipboard) Level Maintenance - required maintenance accomplished by ship's force.

FIBER OPTIC CHARACTERISTICS

A Typical optical fiber consists of three parts: core, cladding and buffer. See 2-73, Fiber Characteristics.

GYROCOMPASSING AND CALIBRATION.—

A four-step, timed procedure accomplishes the gyrocompassing and calibration sequence. This sequence takes approximately 4 hours and must be completed before the gyrocompass is capable of providing full accuracy outputs. The software program estimates latitude if none was entered by the operator. In either case, latitude information will be updated at the end of the gyrocompassing and calibration sequence. At the completion of the sequence, the MODE NAV indicator light will come on, and the MODE ALIGN indicator light will go out, indicating the gyrocompassing and calibration sequence is completed. Table 4-1 details this sequence.

APPARENT ROTATION OF THE GYROSCOPE

A gyroscope, if set on any part of the earth's surface with the spinning axle not parallel to the earth's polar axis, appears to rotate, over a 24-hour period, about a line passing through the center of the gyroscope and parallel to the earth's axis. This apparent rotation is in a counterclockwise direction when viewed from south to north. The path that the north axle describes in space is indicated by the line EAWB back to E (fig. 4-10).

CABLE MARKING

A typical IC cable designation is C-MB144. The letter C denotes the service (the IC system). The letters MB denote the circuit, engine-order system, which may actually include wires of circuits 1MB, 2MB, 3MB, and so on. The number 144 denotes cable number 144 of circuit MB.

System Hardware

A typical hardware configuration for the NAVSSI system is show in Figure 4-61. The DCS is normally located in the chart room, and the RTSs are located in the forward and aft Interior Communication (IC) rooms. Most NAVSSI installations include the NAVSSI Bridge Workstation (BWS). The BWS is a fully functional, remote operator, station for the DCS providing NAVSSI display and control capabilities to ship's force on the bridge.

Paralleling of Circuits

All primary circuits are provided with a tie line between their respective switchboard or switchbox for cross-connection with their auxiliary circuits. The tie lines are fitted with a tie switch at one end and a tie + (tie plus) switch at the other end. The tie switch is normally open and is closed only to parallel two circuits. The tie + switch is normally closed and is opened only in the event of casualty, to disconnect the defective circuit or tie line.

Nonvital Systems

An IC system classified as nonvital (NV), if disabled, would not impair the fighting effectiveness or maneuverability of the ship.

FLUKE Multimeter Series III (Models 77/75/23/21)

An instrument designed to measure electrical quantities. A typical multimeter can measure alternating- and direct-current potential differences (voltages), current, and resistance, with several full-scale ranges provided for each quantity.

SWITCHBOARD MAINTENANCE

Another of your duties as an IC Electrician is the maintenance of the power distribution systems assigned to your division. Normally, the required inspections and cleaning are outlined on maintenance requirement cards (MRCs). When the inspection and cleaning is due, you often think only of the main IC switchboard. The small local IC switchboards located in the engineering spaces and the remote sections of the ship are often forgotten. Auxiliary IC panels may have their own MRCs.

SELECTOR SWITCHES

At stations where only two circuits are involved, a double-throw lever or double-throw rotary snap-type selector switch is used rather than the larger rotary type.

Testing Cables

Because of the variables in IC cables, such as cable length, type, or the temperature of the cable sheath, no single minimum insulation resistance reading for IC cabling can be given. For most IC cabling a reading of 0.2 megohm for each conductor is considered minimum. For the more extensive sound-powered telephone circuits, insulation resistance readings of 50,000 ohms is the acceptable minimum. For short cable runs, minimum insulation resistance should be well above 50,000 ohms.

LATITUDE CORRECTION

Because the latitude error reverses sign between north and south latitudes, the d-c current is introduced in one output winding of the pickoff for north latitudes and in the other output winding for south latitudes. This reverses the direction of the corrective torque. The switching function is manually performed as an equipment control function. Magnitude of the torque is varied to agree with the latitude of operation.

Cartridge Fuses

Before fuses of greater than 10-ampere capacity are pulled, the switch for the circuit should be opened. Whenever possible, this precaution should be taken before any size fuse is pulled or replaced. Approved fuse pullers must be used for removing fuses. Fuses should never be short-circuited or replaced with fuses of larger current capacity.

LAMPS AND LAMP HOLDERS

Both neon and incandescent lamps are used in the IC switchboard. Neon lamps are used as synchro overload and blown fuse indicators, and incandescent lamps are used for power indication.

CABLE RACK

Cables must be supported so the sag between supports, when practicable, will not exceed 1 inch. Five rows of cables may be supported from an overhead in one cable rack; two rows of cables may be supported from a bulkhead in one cable rack. As many as 16 rows of cables may be supported in main cableways, in machinery spaces, and boiler rooms. Not more than one row of cable should be installed on a single hanger.

Sound-Powered Headset-Chestsets

Capacitor C2 provides for power-factor correction and improves the acoustical quality of the set.

JA

Captain' battle circuit

X40J

Casualty communication circuit

FAULT INDICATORS

Circuit cards and assemblies in the synchro signal amplifier we monitored by hard-wired BITE. The 1X heading amplifier, 36X heading amplifier, roll amplifier, pitch amplifier, and inverter in the synchro signal amplifier have fault indicators located on the individual circuit cards. The fault indicator on the inverter sets when the inverter or inverter magnetics module fails. A fault in any of these circuit cards or module will cause the fault indicator on the respective faulty circuit card to set and a BITE fail signal to be sent to the fault summary logic located in the inverter. The inverter then sends out a signal causing the FAULT BFR indicator on the control-indicator to set.

Class 1

Class 1 IC systems are systems that are essential to the safety of the ship and ship personnel. Class 1 IC systems are energized at all times. The switchboard plate is colored yellow on surface ships, and the symbol for submarines is a rectangle within a hexagon.

Class 2

Class 2 IC systems are systems that, together with class 1 systems, are essential to ship control. Class 2 systems are energized when the ship is preparing to get underway, standing by, underway, and anchoring, and until the ship is secured. The switchboard plate is colored black on surface ships, and the symbol for submarines is a rectangle.

SYNCHRO SIGNAL CONVERTER ASSEMBLY

Converts and amplifies pertinent weapon parameters for interfacing weapons systems. In navigation control switchboards, this unit amplifies pitch, roll, heading, and various velocity signals from the IC Switchboard and Data Converters.

Setting Correction Devices

Correction device settings for the Mk 23 gyrocompass include the manual speed setting on the speed unit, the latitude control knob setting on the control panel, and the latitude switch setting on the rear of the control panel.

PARALLELING

Cross connecting two or more sound-powered circuits.

Cross talk

Cross talk is the effect created when an AC signal from one lead in a cable induces a small voltage into the adjacent lead. Crosstalk, while usually always present, is at a relatively low audio level and will be heard as a faint background conversation during a call.

2JZ

Damage and stability control

Maintenance of Relays

During preventive maintenance you should check for charred or burned insulation on the relay and for darkened or charred terminal leads. Both of these conditions indicate overheating, and further investigation should be made to determine the cause. One possible cause for overheating is loose power terminal connections, allowing arcing at the connection.

UNIT 1

Handset HS1 is a standard H-203/U sound-powered telephone handset. Handset holder MP 1 is a standard holder for the H-203/U sound-powered telephone handset. The holder is mounted near call-signal station A1.

TYPE CLS

Has the same switching configuration as the Type LS, except that it is only available in the manual version. The CLS is ideal for installation where space is restricted.

Paralleling of Circuits

In an extensive sound-powered telephone system, paralleling of circuits has both advantages and disadvantages. One advantage is that it allows a controlling station to extend supervision over several different stations, using fewer talkers. Another advantage is that if communications is lost to one of the primary stations, the talker can easily reestablish communications with the control station by unplugging the headset from the primary jackbox and plugging it into the auxiliary jackbox.

OPERATING THE MK 23 MOD 0 GYROCOMPASS

In case of follow-up system failure, place the operation switch in the CAGE position immediately and the power switch in the OFF position.

STOWING HEADSET-CHESTSETS

In enclosed spaces, you should stow headset-chestsets on hooks. In machinery spaces and on weather decks, you should stow these sets in stowage boxes, which are designed for stowing one set or up to six sets.

Conventional optical fiber cable minimum bend diameters

Microbends can cause high-order modes to reflect at angles that will not allow further reflection. The light is lost. Microbends can occur during the manufacture of the fiber or can be caused by the cable. Manufacturing and cabling techniques have advanced to minimize microbends and their effects. See figure 2-75.

MODULAR CABLE SUPPORTS

Modular cable supports (fig. 2-50) are installed on a number of naval ships. The modular method saves over 50 percent in cable-pulling time and labor. Groups of cables are now passed through wide opened frames instead of inserted individually in stuffing tubes. The frames are then welded into the metal bulkheads and decks for cable runs.

SHIP'S SERVICE POWER DISTRIBUTION SYSTEM

Most ac power distribution systems in naval vessels are 450-volt, 3-phase, 60-Hz, 3-wire ungrounded systems.

TYPES AND SIZE DESIGNATIONS OF CABLES

Most cables and cords contain a continuous, thin, moisture-resistant marker tape directly under the cable or cord binder tape or jacket at less than 1-foot intervals. This tape shows the name and location of the manufacturer; the year of manufacture; the military specification number of the cable; and the progressive serial number. The serial number is not necessarily a footage marker. A serial number is not repeated by a manufacturer in any one year for any one type and size of cable or cord.

Central Control Station Local IC Switchboard

On ships with a central control station, a local IC switchboard is provided to energize the machinery control IC systems.

Engine-room Local IC Switchboard

On some ships, a local IC switchboard is provided in each engine room to energize local IC alarm, warning, and indicating systems.

ABT DEVICE

One of the more common ABTs used with IC switchboards is the ABT-1A2. This model operates on 120-volt, 60-Hz, single- or 3-phase systems.

OVERLOAD RELAYS

Overload relays are provided in motor controllers to protect the motor from excessive currents. Excessive motor current causes normally closed overload relay contacts to open, which break the circuit to the operating coil of the main contactor, and disconnects the motor from the line. Overload relays are of the thermal or magnetic type.

PANEL 3

Panel 3 is supplied with 120 volts dc from the 450-volt supply of panel 1 via two remotely located rectifiers. A switch on the front of panel 3 allows the operator to select either of the two rectifiers. Indicator lights on the panel indicate which of the two rectifiers is in operation.

PANEL 3

Panel 3 is supplied with 250 volts dc from one of two 450-volt, 3-phase, 60-Hz motor generators. Two stop-start switches, power available indicator lights for each source, and a voltmeter are located on panel 3. The motor generators obtain their power from the 450-volt, 60-Hz, 3-phase bus.

IC/L Pressure Switches

Pressure-operated switches are normally SPST, quick-acting switches. Each contains either a bellows or a diaphragm that works against an adjustable spring. The spring causes the contacts to close automatically when the operating pressure falls below a specified value. The pressure at which the switches operate is adjustable within ranges, such as 0-15, 15-50, and 50-100. Make this adjustment at the screw marked HIGHER (fig. 2-13). These switches can be used also to indicate an increase in pressure above a predetermined point.

IC/L Pressure Switches

Pressure-operated switches are used with the lubricating oil, low-pressure alarm system; air pressure alarm system; and booster-feed pressure alarm system. Figure 2-13.—Type IC/L pressure switch. 2-14

System Maintenance

Preventive and corrective maintenance for the system should be accomplished according to the applicable MRCs and associated technical manual(s) for the system.

Primary Circuits

Primary circuits provide communication for as primary control and operating functions associated with ship control, weapons control, aircraft control, engineering control, and damage control. Primary circuits are designated JA through JZ.

SYSTEM SETUP INDICATOR ASSEMBLY

Provides a visual indication of launcher assignment to a specific fire control system.

SNAP SWITCH ASSEMBLY

Provides normal control of switchboard firing supply signals to the launching systems.

SWITCH CONTROL ACO AND POTENTIAL TRANSFORMER ASSEMBLY

Provides the control voltages and produces the potentials for remote control of the remote-operated switches.

Maintenance of Relays

Relay coils usually consist of a single coil. If a relay fails to operate, the coil should be tested for open circuit, short circuit, or short to ground. An open coil is a common cause of relay failure.

RELAYS

Relays are classified according to their use as control relays or power relays.

Fuse Holders

Removal of the fuse is accomplished by pushing and turning the fuse carrier in a counterclockwise direction, again similar to the removal of a bayonet-base lamp. The types FHL10G and FHL11G accommodate 1 1/4- by 1/4-inch fuses. The type FHL10G will hold two fuses and can therefore be used to fuse both sides of the line, or, in conjunction with a type FHL11G, will fuse a 3-phase line. Type FHL12G will accommodate 1 1/2- by 13/32- inch fuses. When these fuse holders are mounted in a drip-proof enclosure, they maintain the drip-proof integrity. They also possess the ruggedness and the vibration and high-impact shock resistance necessary for shipboard use. 2-34

SWITCHING CIRCUIT

Resistor R31 provides a bias to the base of Q6, which normally holds Q6 in a saturated state, maintaining K1 in an operated condition. When the local talk switch is closed, the base of Q6 is connected to ground through the 4.8 ohms of the mouthpiece. Presently the voltage across Q6 from base to ground becomes less than the emitter bias voltage provided by voltage divider network R32 and R33; therefore, the transistor becomes reverse biased and Q6 becomes nonconductive, de-energizing and restoring K1.

CASUALTY POWER DISTRIBUTION SYSTEM

Risers, consisting of a terminal at each end connected by permanently installed cable, provide connection points for 3-phase portable cables between decks. Bulkhead terminals are permanently installed in watertight bulkheads in chosen locations. Bulkhead terminals are used to connect the portable cables on opposite sides of bulkheads. This enables power to be transmitted through compartments without the loss of watertight integrity.

Singlemode

SINGLE MODE FIBER. Another way to reduce modal dispersion is to reduce the core's diameter until only one ray will propagate down the fiber. The single-mode fiber has an exceedingly small core diameter of only 5 to 10 microns. Standard cladding diameter is 125 microns. Since the fiber carries only one mode, modal dispersion does not exist. Therefore, it has less loss per kilometer than multimode fiber, and is used in long haul situations. Singlemode fibers easily have a potential bandwidth of 50 to 100 Ghz/km. However, it is more difficult to couple light into the fiber and although modal dispersion is reduced, waveguide dispersion may create problems.

Stuffing Tubes

Sealing plugs are available for sealing nylon stuffing tubes from which the cables have been removed. The solid plug is inserted in place of the grommet, but the slip washers are left in the tube (fig. 2-53, view B).

Auto Cal Mode

Setting the MODE switch to AUTO CAL at anytime after completion of the leveling sequence places the equipment in the AUTO CAL mode. This mode starts an automatic recalibration sequence to determine new gyro biases, accelerometer biases, and latitude corrections. These new values are automatically averaged with old values to accomplish equipment recalibration.

Data Display

Several pieces of data are available for display on the control indicator panel. The data available for display is latitude, electromagnetic (EM) log, ship's heading, pitch, roll, and test (table 4-2). The desired data is displayed by setting the DSPL SEL switch to the appropriate position. Also, under software control, but not selectable, are the MODE, ALIGN indicator, and the MODE, NAV indicator. When the alignment sequence is complete, the software program turns the MODE, NAV indicator on, and the MODE, ALIGN indicator off.

IC AND ACTION CUT-OUT (ACO) SWITCHBOARDS

Shipboard IC systems are defined as anything that causes an audible or visual signal to be transferred within or between the compartments of a ship. They provide a means of exercising command within a ship and include voice interior communications, alarm, warning, ship's control, entertainment, gyrocompass, and plotting systems.

TYPES AND SIZE DESIGNATIONS OF CABLES

Shipboard electrical cables are identified according to type and size. Type designations consist of letters to indicate construction and/or use. Size designations consist of a number or numbers to indicate the size of the conductor(s) in circular mil area, number of conductors, or number of pairs of conductors, depending upon the type of cable.

OPERATIONAL CHECK

Slowly open and close circuit breakers a few times manually, See that trip shafts, toggle linkages, latches, and all other mechanical parts operate freely and without binding. Make sure that the arcing contacts meet before and break after the main contacts. If poor alignment, sluggishness, or other abnormal condition is noted, adjust according to the technical manual for the circuit breaker.

IC AND ACTION CUT-OUT (ACO) SWITCHBOARDS

Some of the newer ships also have a combat systems switchboard. On some ships this switchboard serves as an interface between certain IC and non-electronic navigation systems and the ship's combat system. This switchboard also supplies power and action cutout (ACO) switching for certain IC systems. On other ships, this switchboard contains no distribution facilities. The switchboard is confined to ACO switching for the various instruments at navigational stations and inputs to the weapons control systems.

Principles of Operation of the Transmitter Unit

Sound waves are vibrations that cause compressions and rarefaction in the atmosphere in which they travel. In sound-powered telephones, the sound waves created by a speaker's voice cause the diaphragm in the transmitter unit to vibrate in unison with the sound wave vibrations. Figure 5-8, view A, shows the armature of a transmitter unit when there are no sound waves striking the diaphragm. Note that the armature is centered between the pole pieces with the magnetic lines of force passing from the north to the south pole and that there are no lines of force passing lengthwise through the armature.

Lever-Operated Switches

Special switches are used where the standard switches cannot be used. For example, the diving alarm switch on the submarine bridge must be pressure-proof. For submarine service, a distinctive shape is used for the operating lever knob or heads of alarm switches in the conning tower and the control room (where illumination is low) to avoid the possibility of confusion in operating the proper switch. A square-shaped knob is used for the diving alarm switch, a star-shaped head for the collision alarm switch, and a standard rounded head for the general alarm.

Stuffing Tubes

Stuffing tubes (fig. 2-51, views A, B, and C) are used to provide for the entry of electric cable into splash-proof, spray tight, submersible, and explosion proof equipment enclosures. Cable clamps, commonly called box connectors (shown in fig. 2-52), may be used for cable entry into all other types of equipment enclosures. However, top entry into these enclosures should be made drip-proof through stuffing tubes or cable clamps sealed with plastic sealer.

Stuffing Tubes

Stuffing tubes are made of nylon, steel, brass, or aluminum alloys. Nylon tubes have very nearly replaced metal tubes for cable entry to equipment enclosures.

SYNCHRO OVERLOAD TRANSFORMERS AND INDICATORS

Synchro overload transformers and indicators are used in the ACO section of the IC switchboard to alert operating personnel of a casualty or overload in the associated circuit.

System Operating Controls

System operating controls (Figure 4-42) consist of the power controls and indicator; a system fault indicator; a keypad, which provides all operator control interface; a menu display, which provides all mode and status information; and displayed menus, which allow selection of various control functions and display of specific data.

MAIN IC SWITCHBOARD

Terminal boards are mounted on the rear of each panel. Cables are terminated at the terminal boards on the inside of the panel. Wiring between the terminal boards and the door-mounted equipment is installed to ensure free-swinging of the doors without interference from, or damage to, the wiring harness.

TYPE JR

The 3JR switch uses one of the stationary contacts as a common terminal. This stationary contact is connected, in turn, to each of the other stationary contacts of the section by a single-wiper contact. The 3JR switch is used for selecting one of several (up to seven) inputs.

PANEL 4

The 450-volt, 400-Hz, 3-phase power for panel 4 is received from a motor generator or a static power supply. The 120-volt, 400-Hz, 3-phase power is received from a bank of transformers. A voltmeter, a frequency meter, and an ammeter are also installed on panel 4 for monitoring by watch standers and maintenance personnel.

LATITUDE CORRECTION

The E-core pickoff is used to produce this torque. A d-c current is introduced in one output winding of the E-core pickoff on the vertical ring. The magnetic field produced attracts the armature on the gyrosphere and a counteracting vertical torque is created.

Reference Speed Selection

The EM log velocity information is monitored for reasonableness by the software program. When it determines that the velocity information does not meet the reasonableness test, the processor will command the equipment to ignore the velocity data and operate in the free-inertial state. The processor will also initiate a reference speed off signal, causing the REF SP, OFF indicator to light. The operator can override the reasonableness test by setting the REF SP switch to OVRD LOG. In the OVRD LOG position, the processor disables the velocity monitor and commands the software program to use the EM log velocity information for damping purposes. The REF SP, OFF indicator will go off, and the OVRD LOG indicator will come on, indicating the equipment is operating in a damped state.

DIGITAL FLUX GATE MAGNETIC COMPASS SYSTEM (DFGMC)

The MV103AC, MV103ACS and MV103DG Digital Flux Gate Magnetic Compass (DFGMC) Systems constitute an integral part of the ship's navigation system. These systems were designed as a replacement for the wet globe magnetic compasses found on many older vessels. DFMGC systems are electronic compass systems, which use digital processing techniques to determine the heading of a vessel referenced to magnetic North. Magnetic heading data is displayed to the operator in numerical format on a liquid crystal display at the helm and may be sent to other equipment in the form of RS-232 or RS-422 serial data.

General Description

The Mark 27 Gyrocompass consists of three major assemblies: Master Unit, Electronic Control Assembly and Power Converter.

Design Features

The Mark 27 Gyrocompass contains a gyroscope controlled in a manner to make it seek and continuously align itself with the meridian and thereby point to true north. The properties of the gyroscope in combination with the rotation of the earth and the effect of gravity produce this result. The Mark 27 Gyrocompass differs from previous gyrocompasses in that a gimbal system is used which reduces the complexity of the equipment.

SPERRY MK 27 GYROCOMPASS SYSTEM

The Mark 27 Mod 0 Gyrocompass Equipment, shown in figure 4-26 and described in this manual, is small, compact, has a low power demand, and is capable of furnishing an accurate heading indication under the severe operating conditions encountered in small boats, amphibious vehicles and craft, submarines, and larger combatant vessels. The compass can be read directly or heading data can be transmitted to remote systems and indicators.

Master Unit

The Master Unit consists of a shock-mounted, fluid-filled binnacle which houses the sensitive element. The unit is sealed and designed for deck mounting. To prevent damage when not in use, the sensitive element can be caged by depressing a button on the top of the unit. The viewing window for the compass card is oriented on the after side of the compass. The dial has dark-adapted illumination and its brightness is adjustable at the Electronic Control Assembly. This will be discussed in further detail later in the chapter.

BATTERY SET

The battery set is installed in the electrical equipment cabinet (fig. 4-34). It is secured in the cabinet by quick-release fasteners. The battery set consists of a battery, isolation diodes, fuses, and sensing circuits. The battery consists of 60 sealed lead-acid storage cells. They are connected in series-parallel, five parallel branches, consisting of 12 cells per branch, to provide a nominal 24-volt output for approximately 30 minutes during normal power failure. The battery set weighs 70 lbs and requires careful handling by two persons when moved. The battery is under a continuous charge, provided by electronics in the control power supply. The fuses provide overload protection in the battery charger input circuit and the battery output. The sensing circuits consist of a high-voltage sensing circuit, a low-voltage sensing circuit, and a temperature sensing circuit. The output of these sensing circuits go to BITE circuits in the control power supply and are routed to BITE indicators on the control indicator.

FAULT INDICATORS

The circuit cards, in the control section of the control power supply, are monitored and tested by the processor. When a circuit card fails, the FAULT CTR and ALARM indicators on the control indicator are energized. A combination of the six indicators, located inside the control power supply, will be energized, indicating which circuit card is faulty.

Fiber Cladding

The cladding surrounds the core and provides the reflective surface that allows light to propagate along the core to the distant end. The cladding is also a solid section of transparent glass or plastic, however, a significant decrease in density at the core-to-cladding interfaces helps keep light loss to a minimum. The cladding diameter of most glass fibers is 125 microns, but can be as large as 140 microns.

APPARENT ROTATION OF THE GYROSCOPE

The combined earth rate effects at this point make the gyro appear to rotate partly about the horizontal axis and partly about the vertical axis. The horizontal earth rate causes the gyro to tilt, whereas the vertical earth rate causes it to turn in azimuth with respect to the earth. The magnitude of rotation depends on the latitude of the gyro.

BUS

The common connection between a group of line cutout switches. It may be in a single section or divided; it maybe connected to a jack outlet or be free.

Fiber Core

The core will always be denser than the cladding in order to minimize the loss of light. The core diameter may range from around 2 microns for the smallest single-mode glass fibers, to 100 microns for large multi-mode glass fibers. Most fibers used in military applications are made from superior glass materials.

Maintenance of Solenoids

The first step to be taken in checking an improperly operating solenoid is a good visual inspection. The connections should be checked for poor soldering, loose connections, or broken wires.

Use of Transverse Coordinates Reference System

The geographic 90-degree and 270-degree meridians become the Transverse equator, and the geographic equator becomes the Transverse 90-degree and 270-degree meridians. (Refer to Figure 4-56.)

Gyro Motor

The gyro is a complete subassembly and is statically balanced as a unit. The stator winding on the shaft and squirrel cage on the gyro wheel constitute a 4-pole, 3-phase induction motor. The speed is about 11,800 rpm counterclockwise from the south end, and the motor uses 7 watts of electrical power.

MAIN IC SWITCHBOARD

The latest type of main IC switchboard is the front-service switchboard. This switchboard is constructed so installation, operation, and maintenance can be accomplished entirely from the front of the switchboard. The switchboard can be mounted against a bulkhead because no access space is required in the rear of the board. This results in a saving of space, which is most important aboard ship.

Switchboard Circuit

The line cutout switch portion of the switchjack either connects or disconnects a telephone station jackbox from its circuit. The jack portion of the switchjack either parallels the telephone station associated with a particular switchjack to another circuit or parallels two entire circuits. This method of paralleling is accomplished by a patching cord. A patching cord is a short length of portable cord having a jackplug at each end. The lines and tie switches are also installed to allow paralleling with circuits on other switchboards or switchboxes.

STATION

The location of a jackbox where a sound-powered telephone operator mans a sound-powered telephone.

Magnetic Overload Relay

The magnetic type of overload relay has a coil connected in series with the motor circuit and a tripping armature or plunger. When the motor current is excessive, the armature opens the overload relay contacts. Magnetic overload relays may be of the instantaneous or time-delay type.

Conventional optical fiber cable minimum bend diameters

The minimum short-term bend diameter for conventional optical fiber cable is eight times the cable outside diameter. The minimum long-term bend diameter for conventional optical fiber cable is sixteen times the cable outside diameter.

MODULAR CABLE SUPPORTS

The modular method of supporting electrical cables from one compartment to another is designed to be fireproof, watertight, and airtight.

Looping

The only way to break a loop after it has formed is to end one of the calls. The press-to-talk switches on both handsets of the stations involved must be released to end the call. NEVER tape down the press-to-talk switch of a handset. A taped down switch will act as a continuous call even when a call is ended.

SPERRY MK 23 GYROCOMPASS SYSTEMS

The original Sperry Mk 23 gyrocompass (Mod O) has had several minor modifications and one major modification (Mod C-3). Only the Mk 23 Mod O and the Mk 23 Mod C-3 will be discussed in this training manual.

Ac Shunt Relay

The pull-in and dropout current values may be adjusted. In figure 2-24 the various adjustment points of the ac shunt-type relay are indicated. The spring, A, and the setscrew, E, control the pickup and dropout values. Before the relay is adjusted, the screw, F, should be set to clear the armature when the armature is in the closed position. The pull-in value can be raised by increasing the spring tension or by increasing the armature gap. Figure

SIGNAL DEVELOPMENT

The roll, pitch, and heading sine and cosine signals from the resolver preamplifier and the true heading sine and cosine signals from the true heading converter are also sent to the A/D multiplexer. The A/D multiplexer sends these analog signals to the A/D converter, where each sine/cosine part is converted to the tangent of the respective angle, in digital format. The tangent values of the roll, pitch, and heading angles are sent to the processor for use in program computations and data updates.

THE FREE GYROSCOPE

The rotor and both gimbals are pivoted and balanced about their axes. The axes (marked X, Y, and Z) are perpendicular to each other, and they intersect at the center of gravity of the rotor. The bearings of the rotor and two gimbals are essentially frictionless and have negligible effect on the operation of the gyroscope.

LINE

The smallest portion of a circuit that can be electrically isolated by operation of switches at a central point. For example, in the switchboard or switchbox types of circuits, a line is the pair of wires between the line cutout switch on a switchboard (or switchbox) and a telephone jackbox; in string circuits, a line is a pair of wires interconnecting the various jackboxes in the circuit.

SOLENOIDS

The soft-iron core will also influence the strength of the magnetic flux produced by the coil. The strength of the field is greatly increased by the use of a soft-iron core due to the greater permeability of iron in respect to air. Consequently, by using an iron core, a greater flux density can be produced for a given number of ampere-turns.

Reference Speed Selection

The software program controls the reference speed selection function. The REF SP switch is positioned by the operator to define to the software program the operational mode required. In the OVRD LOG position, the REF SP switch provides a ground via the dimming control circuit card to energize the OVRD LOG indicator. The REF SP OFF indicator is controlled by the processor.

Maintenance of Solenoids

The solenoid should then be checked for opens, shorts, grounds, and correct resistance with an ohmmeter. If when you check the resistance of the solenoid the ohmmeter indicates infinity, the solenoid is open-circuited and should be replaced. If the ohmmeter reads zero or less than the specified resistance, the coil is shorted and should be replaced. However, if the resistance of the coil is higher than specified (but not infinity), look for a poor contact or a damaged conductor. If the fault cannot be found or corrected, replace the solenoid. Another check possible with the ohmmeter is to determine if the coil is grounded. If the coil is grounded, re-insulate the solenoid.

SWITCHING CIRCUIT

The switching circuit is activated when the amplifier is energized. With power available and neither local nor remote talk switches closed, the relay (K1) is operated. When operated, the depression of a remote talk switch will have no effect upon K1; that is, it will remain operated. However, when one of the six local talk switches is depressed, the circuit to K1 is changed and K1 restores.

SYNCHRO SIGNAL AMPLIFIER

The synchro buffer amplifiers provide the voltage and power levels for the gyrocompass heading, pitch, and roll synchro output signals. The inverter power supply converts the battery output to 115-volt, 400-Hz power and converts this to the proper dc levels for the synchro signal amplifier. The inverter power supply also produces ac power for the equipment cooling fans and a vital heading reference output for the gyrocompass set when normal single-phase, 400-Hz power is lost. The inverter power supply also contains BITE summary logic for the synchro signal amplifier.

Units 1, 2, and 3

The terminal stations are units 1, 2, and 3. These terminal stations provide the means of selecting and calling other stations in the system.

IC TEST SWITCHBOARDS

The test switchboard may also contain ac and dc voltmeters, ammeters, test jacks, test leads, lamp test sockets, a multimeter, and a fuse tester. These capabilities permit comprehensive bench testing of all types of IC equipment.

IC TEST SWITCHBOARDS

The test switchboards are normally set up to provide the following test outputs: •120 volts, 60 Hz, single phase •0 to 230 volts, 60 Hz, single phase •120 volts, 400 Hz, single phase •80 volts, 20 Hz, single phase •120 volts dc •0 to 120 volts dc

Thermal Overload Relay

The thermal type of overload relay has a heat-sensitive element and an overload heater connected in series with the motor circuit (fig. 2-44). When the motor current is excessive, heat from the heater causes the heat-sensitive element to open the overload relay contacts. As it takes time for the heat-sensitive element to heat up, the thermal type of overload relay has an inherent time delay. Thermal overload relays may be of the solder-pot, bimetal, single-metal, or induction type.

Thermal Overload Relay

The thermal type of overload relay is designed to open a circuit when excessive current causes the heater coils to reach the temperature at which the ratchet mechanism releases. The heater coils are rated so that normal circuit current will not produce enough heat to release the ratchet mechanism.

LATITUDE CORRECTION

The tilt of the ballistic causes horizontal torques which precess the gyro in azimuth. Horizontal earth rate affects a gyro when located anywhere except at the poles. Horizontal earth rate likewise causes the gyro to tilt. The torque developed by the tilted ballistic will be just enough to keep the gyro precessing at a rate equal and opposite to the vertical component of earth rate. The higher the latitude, the greater must be the tilt of the spin axis to keep up with the higher vertical earth rate.

SYNCHRO OVERLOAD TRANSFORMERS AND INDICATORS

The transformers are wired in series with the secondary connections of selected synchro torque instruments. Type B and C transformers are used for 60-Hz and 400-Hz circuits, respectfully.

Sound-Powered Amplifier AM-2210N/WTC and AM-2210G/WTC

The transistorized AM-22l0N/WTC and AM-2210G/WTC sound powered amplifiers (fig. 5-15) are two of the most common types presently in wide use throughout the fleet and are the ones that will be discussed in this training manual. Electrically, the units consist of an audio amplifier, a switching circuit, and a power supply. The incorporation of transistors in the audio and switching circuits and silicon junction diodes in the power supply creates a highly reliable static condition. The AM-2210N/WTC will replace the AM-2210G/WTC Sound Powered Amplifier.

Fuse Holders

The type EL-1 fuse holder consists of a base and a plug, as shown in figure 2-29. The base extends behind the panel, and the plug containing the fuse is screwed into the base. Behind a hole in the plug cap is a small neon lamp that serves as a blown-fuse indicator, lighting when the energized circuit through the holder is interrupted by the blowing of a fuse. Series resistors of different values are used with the lamp on 125- and 250-volt circuits, except for the midget holder, which is rated for 125 volts only.

Mechanical Switches

The types of mechanically operated switches are the push-action (type A-S) and the cam-action (types P and P41). The push-operated switch, provided for bulkhead mounting, is a single-throw or multiple-throw, momentary action, normally open push switch. The push-action mechanism uses a straight-line movement of the shaft to operate the electrical contacts. The cam-action switch consists of two SPDT sensitive switches operated by two adjustable cams mounted on the rotor shaft (fig. 2- 16).

SWITCHES

The types of switches usually found on IC switchboards are the JR, JL, toggle, and rotary snap switches. These switches were discussed in chapter 2 of this manual.

NORMAL POWER

The unregulated 28 volts dc is applied to the 5-volt and 13-volt regulators. The 5-volt regulator reduces the unregulated 28 volts dc to a regulated 5 volts dc, which is distributed to all using circuit cards and assemblies. The 13-volt regulator reduces the unregulated 28 volts dc to a regulated 13-volt dc level, which powers the DC/DC module. The 13-volt regulator is turned on before the 5-volt regulator to allow the DC/DC module and equipment to stabilize before the distribution of the 5 volts dc. The DC/DC module provides output voltages of +28 volts, -28 volts, +15 volts, -15 volts, +20 volts floating, +50 volts, and +50 volts floating. Floating indicates those voltages are isolated from power ground.

Watch Standing

The watch stander is also responsible for investigating all blown fuse indications, synchro overload indications, and bus failure alarms.

Linear Switches and Switching Equipment

There are Switchboards for Navigation, Missile Fire Control, Director Control Room. Gun Fire Control, Command and Control, and Digital Fire Control.

GYROCOMPASS SYSTEMS

There are a wide variety of gyrocompass installed on Navy ships in the fleet systems today. Gyrocompasses are identified by the mark (Mk)-modification (Mod) system. The Mk number designates a major development of a compass. The Mod number indicates a change to the major development. The most common type of gyrocompasses found in the fleet today are the electrical gyrocompass systems, such as the Sperry Mk 23 and the Sperry Mk 27.

GYROCOMPASS SYSTEMS

There are also other gyrocompass systems currently being installed on Navy ships today. These are the Stabilized Gyrocompass Set AN/WSN-2, Inertial Navigation Set AN/WSN-5, Ring Laser Gyrocompass (RLG) Inertial Navigation System AN/WSN-7B, and AN/WSN-7 RLG. Operation of the AN/WSN-5 is classified; therefore, only the AN/WSN-2, WSN-7 and 7B will be discussed in this training manual.

BUS SELECTOR

There are two types-AC and DC. They select and route AC and DC bus voltages to their respective meter panels for measurement.

Looping

There is a caution label plate on the front cover of each terminal station to caution operating personnel against excessive traffic.

BUS FAILURE ALARM UNIT

There is usually a bus failure alarm unit for each bus associated with the switchboard.

Linear Switches and Switching Equipment

These Switchboards are located in their respective functional areas. They vary in size from single section bulkhead-mounted units to a bank of deck-mounted sections. Each Switchboard is a custom installation, designed to serve the required needs of a particular type of vessel and its specific mission.

Phone/Distance and Station-to-Station Lines

These markers consist of colored cloth squares for daytime use and red flashlights for nighttime use.

EMERGENCY POWER DISTRIBUTION SYSTEM

This system is separate and distinct from the ship's service distribution generators and switchboards. Each emergency switchboard is supplied by its associated emergency diesel generator. The emergency feeders run from the emergency switchboards and terminate in manual or automatic bus transfer equipment at the distribution panels or at loads for which emergency power is required.

INSTANTANEOUS TYPE

This type operates instantaneously when the motor current becomes excessive. The relay must be set at a tripping current higher than the motor starting current to prevent tripping when the motor is started. This type of overload relay is used mostly for motors that are started on reduced voltage and then switched to full line voltage after the motor comes up to speed.

Time-Delay Fuses

Time-delay fuses are rated as to their time lag characteristics with a minimum blowing time at some overload current. A typical rating is 12 seconds minimum blowing time at 200 percent rated current.

LOSS OF SENSITIVITY

To test a headset for loss of sensitivity, you should depress the talk switch and blow into the transmitter. If the set is operating properly, you will hear a hissing noise in the receiver units. You should listen to one receiver unit and then the other. In most cases, the loss in sensitivity is in the transmitter unit and might be caused by a displacement of the armature from the exact center of the air gap between the pole pieces.

Precession

Torque is a force that tends to produce rotation. Force acts in a straight line, at or on a point. Torque occurs within a plane and about an axle or axis of rotation. If the force acts directly on the point of an axis, no torque is produced.

TRANSMITTER AND RECEIVER UNITS

Transmitter and receiver units are not repairable. If these units become defective, they must be replaced. Both of these items are standard stock items.

TYPE JR

Type JR switches are rated at 120 volts, 60 Hz, 10 amperes. The switch should not be used on dc circuits because of the possibility of severely burned contacts when the switch is operated slowly (teased). The switch is the non-shorting type. Although the blade bridges two adjacent contacts simultaneously (for example, contacts 1 and 2 when the switch is operated), the blade breaks contact 1 before making the next alternate contact 3 (for example, in the 2JR switch, alternate terminals may be connected to an independent source of ac power without danger of short circuit during movement of the switch blade).

SPECIAL USE

Type LSMDU is a multiconductor cable used in degaussing circuits. Type LSTCJA consists of one conductor of constantan (red) and one conductor of iron (gray), and is used for pyrometer base leads.

Paralleling of Circuits

Under normal operating conditions, circuits are usually paralleled to reduce the number of talkers required. As conditions of greater readiness are set, more talkers are assigned and fewer circuits are paralleled. Few, if any, primary circuits are paralleled under the highest condition of readiness.

UNIT 4

Unit 4 is a standard sound-powered telephone single-gang jackbox.

FLASHER ASSEMBLY

Used to flash system indicators when a warning or an emergency condition occurs.

Watch Standing

When a ship is underway, the main IC switchboard should be manned 24 hours a day. On ships where there are two main IC switchboards, the forward main IC switchboard is usually the only one required to be manned. The IC Electrician on watch is responsible for recording hourly voltage, current, frequency, and ground readings of the various buses associated with the IC switchboard.

Executive Override

When a station has received a call and is talking to the calling station at the time a second call is received, the second call is considered an override function. The call hold function cannot be used in this case.

EQUIPMENT CONNECTED

When insulation resistance measurements are made with equipment connected, always record the exact equipment included and the type of tester used so accurate comparisons can be made with similar past or future measurements.

LENGTH OF CABLE

When measured insulation resistance is converted to insulation resistance per foot, the total length of cable to be used is equal to the length of the cable sheath for single-conductor cable and for multiple-conductor cable in which each conductor is used in one leg of a circuit. For example, in an LSTSGA cable with a cable sheath of 100 feet in which the three conductors are phases A, B, and C of a 3-phase power circuit, the total length of the cable is 100 feet, not 300 feet. The reason for this is that each conductor is measured separately. If this cable is connected, either in series or parallel, to a similar cable that has a sheath length of 400 feet, the total length is 500 feet. As another example, 200 feet of type LSMSCA cable (7-conductor cable) connected to 200 feet of LSMSCA-24 cable (24-conductor cable) represents a total cable length of 400 feet.

REPLACING CORDS

When replacing cords, you should always use prepared cords, if possible. Handset cords fitted with terminals at both ends are available through standard stock. Tinsel cord cut to the proper lengths and fitted with terminals for use with the various types of headset-chestset transmitter and receiver units are also standard stock items. DCOP 1 ½ cord is used between the junction box and the plug on a sound-powered headset-chestset. 5

Rigidity of Plane

When the rotor of the gyroscope is set spinning with its axle pointed in one direction (fig. 4-2, view A), it will continue to spin with its axle pointed in that direction, no matter how the case of the gyroscope is positioned (fig. 4-2, view B). As long as the bearings are frictionless and the rotor is spinning, the rotor axle will maintain its plane of spin with respect to a point in space. This property of a free gyroscope is termed rigidity of plane.

Principles of Operation of the Transmitter Unit

When the sound wave rarefaction reaches the diaphragm (fig. 5-8, view C), it recoils, causing the armature to bend in the opposite direction. This action reduces the air gap between the armature and the North Pole. The reluctance between the armature and the upper North Pole is decreased and the lines of force are reestablished through the armature, this time in the opposite direction.

Kickpipes and Deck Risers

When three or more cables pass through a deck in a single group, riser boxes must be used to provide protection against mechanical damage. Stuffing tubes are mounted in the top of riser boxes required for topside weather-deck applications. For cable passage through watertight decks inside a vessel, the riser box may cover the stuffing tubes if it is fitted with an access plate of expanded metal or perforated sheet metal. Stuffing tubes are not required with riser boxes for cable passage through non-watertight decks.

Setting Correction Devices

When you operate the speed unit manually, adjust the speed settings to correspond to the average ship's speed. Change the latitude control knob setting on the control panel when the ship's latitude changes as much as 2°, or as ordered by the ship's navigator. Throw the latitude switch on the rear of the control panel to the 65° position for normal operation when the ship's latitude is above 60°. The position of the latitude switch is immaterial for directional gyro operation.

STARTING THE COMPASS

Where practical, starting procedures should begin at least 2 hours before the gyrocompass is required for service.

Call and Signal Circuits Maintenance

You should accomplish preventive maintenance of call and signal circuits according to the applicable MRCs. Corrective maintenance will usually consist of isolating shorts, grounds, and opens in the circuits and repairing or replacing the audible and visual signal devices used with the circuits.

INSPECTION

You should make a routine inspection of sets before you begin to repair the sets to determine whether you should replace physically defective parts. Many troubles may be located by inspecting the set for damaged cord or insulation; cord pulled out of units; loose units; defective or broken pushbuttons; and broken or damaged parts, such as unit covers, neck strap, chestplate, junction box, plug, and headband.

TYPES OF SWITCHES

Another means of classifying switches is the method of actuation; that is, knife, toggle, push button, or rotary. Further classification includes a description of switch action, such as on-off, momentary on-off, and on-momentary off. Momentary contact switches hold a circuit closed or open only as long as the operator deflects the actuating control.

Control Relays

Control relays are usually known simply as relays. They are frequently used in the control of low-power circuits or other relays, although they also have many other uses. Where multi-pole relays are used, several circuits may be controlled simultaneously. In automatic relaying circuits, a small electrical signal may set off a chain reaction of successively acting relays, which then perform various functions.

Knife Switches

Knife switches are basic power switches from which most modern switches have been developed. A single-pole, single-throw (SPST) knife switch consists of a single copper blade hinged at one end and designed to fit tightly between two copper jaws, or clips, at the other end. An insulated handle is fastened to the copper blade to open and close the switch. Terminals are provided for connecting the leads.

Lever-Operated Switches

Lever-operated switches are available in 1-, 2-, and 3-ganged types. These switches are used in such systems as the fire room emergency signal, general alarm, chemical-attack alarm, steering emergency signal, whistle operation, lifebuoy-release, and flight-crash signal.

Power Relays

Only lightweight control wires are connected from the control switches to the relay coil. Safety is also an important reason for using power relays, since high-power circuits can be switched remotely without danger to the operator.

Maintenance of Relays

Relay contact surfaces must be kept clean and in good operating condition. Contact clearances or gap settings must be maintained according to the relay's operational specifications.

RELAYS

Relays are electrically operated switches. The operating coil can be connected in series with a supply line to the load or shunted across the line.

Maintenance of Solenoids

The plunger should be checked for cleanliness, binding, mechanical failure, and improper alignment adjustment. The mechanism that the solenoid is to actuate should also be checked for proper operation.

Maintenance of Solenoids

The second step should be to check the energizing voltage by use of a voltmeter. If this voltage is too low, the result would be less current flowing through the coil and thereby a weak magnetic field. A weak magnetic field can result in slow, ineffective operation. It could also possibly result in chatter or in-operation. If the energizing voltage is too high, it will in all probability damage the solenoid by either overheating or arcing. In either case, the voltage should be reset to the proper value so further damage or failure will not result.

Series-Type Relays

The series-type relays are operated by circuit current flowing through the coil or coils. This feature makes it possible to use the relay as a field failure relay or for any application where the relay operation is in response to changes in circuit current flow.

Circuit E is divided into the following functional circuits:

1E-Cruising and miscellaneous 2E—Ship control 3E—Engineering 4E—Aircraft control 5E—Weapons control

Sound-Powered Telephone Maintenance

• Do not repair telephones on a dirty workbench. The magnets in the units may attract iron filings, which are difficult to remove. • Before disassembling a set, make a wiring diagram showing the color coding, polarity, or terminal numbers of the lead connections. • Never alter the internal wiring of sets. • Always replace parts exactly as they were before disassembly.

Phone/Distance and Station-to-Station Lines

IC Electricians are responsible for maintaining the sound-powered telephone portion of the bridge-to-bridge phone/distance and station-to-station lines. The lines are made of 1 1/2-inch round, 3-strand, lightweight polypropylene. Each strand of the line has one electrical wire interwoven in it. Sound-powered telephone jackboxes are attached to both ends of each line; the boxes are labeled either BRIDGE-TOBRIDGE or STA.-TO-STA.

Testing Cables

IC cables should be tested with an insulation resistance measuring instrument (Megger). If a Megger is not available, consult NSTM, chapter 300, for alternate methods of testing the insulation resistance.

READINESS

IC systems are also classified according to the extent to which a system contributes to the operational readiness of the ship. There are four classes of readiness: class 1, class 2, class 3, and class 4. Readiness classification only switchboard plates is indicated by color on surface ships and by a specific symbol on submarines.

INSPECTION OF MOVING PARTS

Inspect pins, bearings, latches, and contact and mechanism springs for excessive wear or corrosion and current carrying parts for evidence of overheating. Bolt-on parts/attachments and subassemblies may be replaced by ship's force personnel. Replacement of parts that require major disassembly or subassembly teardown must be accomplished by an overhaul facility or shipyard with circuit breaker repair capability.

CONTACT SURFACE INSPECTION

Inspect the silver alloy contact surface for heavy burning, erosion, or overheating. If any discrepancies are found, replace the contact. Slight burning, pitting, or erosion is acceptable. Carbon deposits should be removed using a dry, lint-free cloth. Loosen deposits according to the MRC. Do not use emery cloth, a file, or sandpaper. If the contacts have deep pitting that penetrates through the contact surface or 50 percent of the contact surface, replace the contact.

(D) Depot

(Shipyard) Level Maintenance - maintenance performed by industrial activities. Depot level maintenance requires major overhaul or a complete rebuilding of parts, assemblies, subassembly and end items, including the manufacturing of parts, modifications, testing, and reclamation.

LUBRICATION

Lubricate bearing points and bearing surfaces, including latches, with a drop or two of light machine oil. Wipe off excess oil.

Replacing Tinsel Cords

1. Open each unit connected to the cord that is to be replaced. 2. Before disconnecting the cord, make a diagram showing the color coding of the wires. 3. Disconnect both ends of the cord. 4. Remove the screw that holds the tie cord, or untie the cord if it is secured to an eyelet. 5. Unscrew the entrance bushing, if provided, and pull the cord through the port. 6. Place the threaded entrance bushing, metal washer, and rubber gasket on the new cord and insert the cord into the entrance port. The cord should be long enough to allow slack after it is connected. 7. Secure the tie cord so that it takes all the strain off the connections; otherwise the wires might be pulled from their terminals. 8. Connect the wires to the terminals. 9. Screw the entrance bushing on the entrance port, drawing the bushing up tightly to secure the cable and to seal the port. 10. Close the unit after all connections have been visually checked. 11. Test the set for proper operation.

Replacing Handset Cords

1. Remove the faulty cord by unscrewing the bushing and disconnecting the wires from the terminals. 2. Place the threaded bushing, washer, and grommet on the new cord. 3. Insert the cord into the handset and connect the wires to the terminals. 4. Screw the bushing into the handset tightly to secure the cable. 5. Test the set for proper operation.

REMOVING HEADSET-CHESTSETS

1. Remove the headband and hang it over the yoke of the transmitter. 2. Remove the plug from the jackbox and replace the jack cover on the jackbox to keep out moisture and dirt. 3. Lay the cord out on the deck and remove any kinks. 4. Coil up the cord, starting from the end that attaches to the chestplate. Coil with the right hand, making the loops in a clockwise direction. The loops should be about 10 inches across. 5. After the cord is coiled, remove the headband from the transmitter yoke and hold the headband in the same hand with the cord. 6. Fold the transmitter yoke flat so that the mouthpiece lays flush against the chestplate connection box, using care not to pinch the transmitter cord. 7. Hold the headband and cord in the left hand and unhook one end of the neck strap from the chestplate. 8. Bring the top of the chestplate level with the headband and cord. Secure the chestplate in this position by winding the neck strap around the headband and coiled cord just enough times so that there will be a short end left over. Twist this end once and refasten it to the chestplate. The set is now made up and ready for stowing, Figure 5-12 shows a properly made up sound-powered telephone headset-chestset.

DONNING HEADSET-CHESTSETS

1. Remove the set from the stowage hook or stowage box. 2. Hold the set and coiled cord in one hand. 3. Unhook the neck strap and unwind the coiled cord. Do not allow the set to dangle by its connecting wires; this could cause open leads. 4. Put the neck strap around the neck and secure it to the chestplate. 5. Put on the receivers and adjust the ear cushions for maximum comfort and exclusion of noise. 6. Straighten out any kinks in the connecting wires. 7. Test the headset for satisfactory operation by blowing into the transmitter with S1 depressed. A hissing noise should be heard in both receivers. 8. Remove the jack cover and connect the plug to the jack.

If prepared cords are not available for repairing headset-chestsets, you can make them from bulk tinsel cord using the following procedure:

1. Strip about 2 inches of the outer layer of insulation from one end of the cord. 2. Remove about one-fourth of an inch of insulation from the ends of the conductors, exercising caution not to damage the tinsel wire. 3. Wind a single layer of 32-gauge tinned copper wire over the tinsel wire, and extend the tinned copper wire about one-eighth of an inch over the rubber insulation. 4. Dip these whipped conductors into melted solder and flatten them slightly when they are cool. 5. Solder the whipped conductor to a lug or cord tip, as required.

The eight major units of the AN/WTC-2(V) sound-powered telephone system are as follows:

1. Unit 1—TA-974/WTC-2(V) sound-powered telephone set 2. Unit 2—TA-975/WTC-2(V) sound-powered telephone set 3. Unit 3—TA-976/WTC-2(V) sound-powered telephone set 4. Unit 4—G-15/A sound-powered telephone jackbox 5. Unit 5—H-200/U headset-chestset 6. Unit 6—J-3523/WTC-2(V) distribution box 7. Unit 7—TS-3687/WTC-2(V) telephone test set 8. Unit 8—BZ-240/WTC-2(V) audible alarm

To become a gyrocompass, a gyro must be modified so it can:

1. align its axis on the meridian plane, 2. align its axis nearly horizontal, and 3. maintain its alignment both horizontally and on the meridian, once it is attained.

Test Features

A Built-In Test (BIT) function incorporating both hardware and software tests continuously monitors operation and periodically performs self-tests to determine the integrity of the AN/WSN-7(V) RLGN and its inputs/outputs. Faults are automatically announced, and fault codes that indicate the type of fault detected are displayed on the local/remote control panels.

Test Features

A Built-In Test (BIT) function, incorporating both hardware and software tests, continuously monitors operation and periodically performs self-tests to determine the integrity of the AN/WSN-7B(V) and its inputs/outputs. Faults are automatically announced and fault codes which indicate the type of fault detected are displayed on the local control panel.

Action Cut-out (ACO) Section

A bank of SR switches is also located on the ACO section of some switchboards. These switches are used to isolate the various speaker groups and alarm contact makers of the general announcing system circuit 1MC.

Units and Assemblies

A calibration PROM, which is installed in socket XU20 on the Sensor Interface CCA (A13) in the card rack, contains calibration parameters for the Indexer Assembly in the AN/WSN-7B(V) cabinet. This PROM is serialized to the Indexer Assembly and must always remain with the system if Sensor Interface CCA (A13) is replaced with a new card. Programmed subassemblies are identified by a part number which includes the hardware with the programmed devices installed. The subassembly part number without the programmed device is also provided; however, only the part number for the subassembly with the programmed configuration is applicable for replaceable assemblies.

Cartridge Fuses

A cartridge fuse (fig. 2-28) consists of a zinc-alloy link enclosed in a fiber, plastic, ceramic, or glass cylinder. Some fiber and plastic fuse cylinders are filled with non-conducting powder. The smaller fuses are used in circuits up to 60 amperes and are made in the ferrule, or round-end cap, type. Large sizes with short flat blades attached to the end caps are rated from 65 to 200 amperes. These blades fit tightly into clips on the fuse block similar to knife-switch clips.

CASUALTY POWER DISTRIBUTION SYSTEM

A casualty power distribution system is installed on certain types of ships to provide the means for making temporary electrical connections if the permanently installed ship's service and emergency distribution systems cables are damaged. The system is limited to those facilities that are necessary to keep the ship afloat and to permit the ship to get out of a danger area. The system also supplies a limited amount of power to armament and directors to protect the ship when it is in a damaged condition.

ALARM RELAYS

A circuit card in the control power supply contains alarm summary logic for the BITE circuits. The alarm summary logic receives hard-wired BITE fault signals, alarm signals from faults detected by the processor, and alarm signals from the transformer rectifier via the control monitor. Any one or all of these signals will cause the alarm summary logic to send a signal to the control indicator, lighting the ALARM indicator, and an alarm relay on signal to the normally energized alarm relay. The alarm relay on signal causes the alarm relay to reenergize, completing the circuit for the malfunction summary alarm.

Conference Calls

A conference call involves the sharing of the same line among a number of terminal stations. The number of participants (stations) involved in a conference call should be limited to five, as each additional station will cause a drop in the audio-signal level. To initiate a conference call, you should perform the following procedure: 1. Place a point-to-point call to the first desired station. 2. Inform the called station that a conference call is being established, and give the called station your station number. 3. Repeat steps 1 and 2 for each terminal station you desire to participate in the conference call. 4. After each station has been contacted, rotate the thumbwheel switches to your own terminal station number and begin the conference. 5. When the conference call is completed, return the handset to its holder, and set the PLACE CALL/ANSWER switch to the ANSWER position. To answer an incoming conference call, you should use the following procedure: 1. Answer the same as you would for a point-to-point call. 2. When the caller informs you that it is a conference call, set the thumbwheel switches to the caller's station number and wait for the conference to begin. 3. When the conference call is completed, return the handset to its holder.

Knife Switches

A double-pole, single-throw (DPST) knife switch (fig. 2-1, view A) has two blades with one set of clips for each blade and an insulated handle that operates both blades simultaneously. Double-throw switches (fig. 2-1, view B) have two sets of clips (one set at each end) so the blades can be thrown into either set of clips to shift from one circuit to another.

THE FREE GYROSCOPE

A free gyroscope is a universal-mounted, spinning mass. In its simplest form, the universal mounting is a system that allows three degrees of freedom of movement. The spinning mass is provided by a heavy rotor. Figure 4-1 illustrates a free gyroscope. As you can see in the figure, the rotor axle is supported by two bearings in the horizontal ring. This ring is supported by two studs mounted in two bearings in the larger vertical ring. These two rings are called the inner gimbal and outer gimbal, respectively. The outer gimbal is then mounted with two studs and bearings to a larger frame called the case.

Fuses

A fuse is a protective device used to open an electric circuit when the current flow exceeds a safe value. Fuses are made in many styles and sizes for different voltages and currents, but they all operate on the same general principle. Each fuse contains a soft-metal link that melts and opens the circuit when overheated by excessive currents.

Stuffing Tubes

A grounded installation that provides for cable entry into an enclosure equipped with a nylon stuffing tube is shown in figure 2-54. This type of installation is required only when radio interference e tests indicate that additional grounding is necessary within electronic spaces. In this case, the cable armor is flared and trimmed to the outside diameter of the slip washers. One end of the ground strap is inserted through the cap; and one washer is flared and trimmed to the outside diameter of the washers. Contact between the armor and the strap is maintained by pressure of the cap on the slip washers and the rubber grommet.

Rigidity of Plane

A gyroscope can be made more rigid by making its rotor heavier, by causing the rotor to spin faster, and by concentrating most of the rotor weight near its circumference. If two rotors with cross sections like those shown in figure 4-3, are of equal weight and rotate at the same speed, the rotor in figure 4-3, view B, will have more rigidity than the rotor in figure 4-3, view A. This condition exists because the weight of the rotor in figure 4-3, view B, is concentrated near the circumference. Both gyroscope and gyrocompass rotors are shaped like the rotors shown in figure 4-3, view B.

Electronic Control Assembly

A plug-in connector on the rear cabinet frame connects external cables to the chassis and permits removal of the chassis from the cabinet. Cables to the Electronic Control Assembly are routed through three stuffing tubes on the rear of the cabinet.

Thermal Time Delay Relay

A heater is mounted around, or close to, the element, with the contacts mounted on the element itself. As the heat causes the element to bend (because of the different thermal expansion rates), the contacts close to operate a relay. The delay time of the bimetallic strips is usually from 1/2 to 1 1/2 minutes and is varied by using metals with different expansion rates or by increasing or decreasing the distance between the fixed and moving contacts.

TIE LINE

A line between two switchboards, two switchboxes, or a switchboard and a switchbox. It connects two circuits and is terminated by a switch at each end.

Steering Gear Room Local IC Switchboard

A local IC switchboard is usually installed in each steering gear room to energize all circuits associated with steering-order and rudder-angle indicator systems.

TYPE KLS

A manual-only linear switch has up to 28 poles in four contact configurations, arranged in a combination of break-before-make and make-before-break contacts. Its reliability is also in excess of 30,000 operations. All versions have a current handling capability of 10 amperes at 115VAC, 60 Hz.

MODES

A mode is simply a path that a light ray can follow in traveling down a fiber. The number of modes supported by a fiber ranges from 1 (Singlemode) to over 100,000 ( >1 = Multimode). This is dependent on the size and properties of the fiber (Core and Cladding).

CABLE RACK

A more complex cable support is the cable rack, which consists of the cable hanger, cable strap, and hanger support (fig. 2-49).

TIE PLUS SWITCH

A normally closed switch at the opposite end of a tie line from the tie switch. It may be opened to clear a damaged circuit.

Stuffing Tubes

A nylon stuffing tube that provides cable entry into an equipment enclosure is applicable to both watertight and non-watertight enclosures (fig. 2-53, view A). Note that the tube body is inserted from inside the enclosure. The end of the cable armor, which will pass through the slip washers, is wrapped with friction tape to a maximum diameter. To ensure a watertight seal, one coat of neoprene cement is applied to the inner surface of the rubber grommet and to the cable sheath where it will contact the grommet. After the cement is applied, the grommet is immediately slipped onto the cable. The paint must be cleaned from the surface of the cable sheath before applying the cement.

CIRCUIT

A quantity of telephone jackboxes connected by one or more lines, either directly or through switchboards and switchboxes, to provide a means of communication between personnel at various stations.

Testing Cables

A reading equal to or above the accepted minimum for the cable concerned indicates that the conductor under test is satisfactory. A reading below the accepted minimum indicates that the insulation resistance of the conductor under test to ground or from one or more of the grounded conductors or both is low. The grounded conductors must then be disconnected from ground, and each conductor tested individually to isolate the low-reading conductor(s).

Paralleling of Circuits

A second disadvantage of paralleling circuits is that as the number of stations on a circuit increases, conversations may increase, resulting in confusion. This can be remedied by all stations exercising good circuit discipline.

OPEN AND SHORT CIRCUITS

A short circuit in a single sound-powered transmitter or receiver unit will render an entire circuit inoperative because all sound-powered telephones on the circuit are connected in parallel. Operation of switchboard or switchbox line cutout switches will allow isolation of a faulty unit. For string circuits, you should disconnect each set in sequence to isolate the faulty unit.

Precession

A simple way to predict the direction of precession is shown in figure 4-4. The force that tends to change the plane of rotation of the rotor is applied to point A at the top of the wheel. This point does not move in the direction of the applied force, but a point displaced 90° in the direction of rotation moves in the direction of the applied force. This results in the rotor turning left about the Z axis and is the direction of precession.

BUS FAILURE ALARM UNIT

A small nickel-cadmium battery provides power for the oscillator. The battery is maintained on a low charge when the supervised bus is energized. The unit will operate on 115 volts, dc or ac, and 60 or 400 hertz without modification.

String Circuit

A string circuit consists of a series of telephone station jackboxes connected in parallel to a common line. There are no line cutout switches provided for cutting out individual stations. However, some string circuits are connected to communication consoles, selector switches, and plotter transfer switchboards. These will be discussed later in this chapter.

TIE SWITCH

A switch at one end of a tie line, usually the end connected to an auxiliary circuit. It is normally open unless the ship's doctrine requires that it be closed.

Switchboard Circuit

A switchboard circuit originates from a sound-powered telephone switchboard. Figure 5-1, view A, is an illustration of a type IC/A sound-powered telephone switchboard. Figure 5-1, view B, shows a section from the sound-powered telephone switchboard. Each telephone station jackbox (fig. 5-2) in the circuit is connected to a switchjack on the switchboard. The switchjack (fig. 5-3) is a combination line cutout switch and telephone jack.

Switchbox Circuit

A switchbox circuit originates from a sound-powered switchbox. Figure 5-4 is an illustration of a type A-17A sound-powered telephone switchbox. Each telephone station jackbox in the circuit connects to a line cutout switch in the switchbox. The line cutout switch either connects or disconnects an individual telephone station jackbox from its circuit. There are also tie lines and tie switches installed to allow paralleling with circuits in other switchboxes or switchboards.

Thermal Time Delay Relay

A thermal time delay relay (fig. 2-22) is constructed to produce a delayed action when energized. Its operation depends on a thermal action, such as that of a bimetallic element being heated. The element is made by welding together two strips of different metals having different thermal expansion rates.

TYPE DLS

A unique linear movement switch because it is capable of switching functions required by digital data systems from shore sites and combatant ships. It provides casualty backup and select switching to Input/Output channels of digital data which are the sole communications link for data exchange between computers and their associated peripherals. The DLS is available in a number of versions, including two weatherproof versions, type R3DLSOS3A3 and type R3DLSO-S3A4, for exposed area usage. It has 160 available poles for wired-loaded switching which can be switched from three positions. It offers remote operation with manual override. Remote-operated versions have fuseholders. Its current handling capability is 2 amperes at 15 VDC.

Water Switch

A water switch consists of a pair of terminals mounted in an insulated base within a cast fitting (fig. 2-17). There is a 7000-ohm, 5-watt resistor connected across the two terminals, which limits the current to the required value for the supervisory circuit when the switch casting is dry. The switch is mounted in the magazine flooding system, and a sprinkling control valve is installed between the switch and the firemain. When the sprinkling control valve is opened, water floods the switch casting and shorts out the 5-watt resistor. With the supervisory resistor shorted, a current of sufficient value to operate the alarm will flow in the circuit.

Water Switch

A water switch is used principally in sprinkling alarm systems (circuit FH).

JACKBOX

A weatherproof enclosure mounted in any convenient location and connected to a sound-powered telephone line. Jackboxes can be single-gang, double-gang, or four-gang types. Gang is a term used for the number of jack outlets in the jackbox.

TYPE JF

An O-ring on the switch shaft within the mounting bushing prevents water from entering the switch. An O-ring is also provided on the outside of the mounting bushing to give a watertight seal against the panel in which the switch is mounted. These features have eliminated the need for a watertight cover over the switch.

Semivital Systems

An IC system classified as semivital (SV), if disabled, would impair the fighting effectiveness of the ship to a lesser extent than the loss of a vital system.

ABT DEVICE

ABTs may have either two or three bus transfer switch positions. Bus transfer switch positions indicate the number of power supplies the ABT is designed to handle. Two-way transfers indicate that the ABT is capable of transferring the load between two sources of power available to the ABT. The two sources are identified as normal (ship's service) and alternate (ship's service) or normal (ship's service) and emergency (service).

Vital Systems

An IC system classified as vital (V), if disabled, would seriously impair the fighting effectiveness and maneuverability of the ship.

TERMINAL MARKING

All IC terminals are identified by insulated sleeving that is stamped with the lead number and the cable number the lead belongs to.

Auto Cal Mode

All gyro functions and outputs are maintained in the AUTO CAL mode. The outputs from the IMU resolvers, representing pitch and roll angles, are applied directly to the synchro signal amplifier. The synchro signal amplifier amplifies the resolver input information and transmits dual-speed synchro information to the ship's equipment. Roll and pitch angle information is also sent to the A/D multiplexer.

Calibration

All magnetic heading sensors operate on the principle that a magnetized needle or card aligns itself with the Earth's magnetic flux field. These devices are also influenced by nearby distortions or disturbances caused by magnetized or magnetizable materials or electrically generated flux fields. The DFGMC has the ability to compensate itself for these disturbances by executing on-demand or continuous self-compensation routines. "Auto-compensation", or calibration, refers to a process in which the DFGMC assesses the local magnetic environment and applies correction factors through embedded software routines.

Amplifier Maintenance

Although by no means trouble free, the AM-2210N/WTC is a highly reliable piece of equipment. When trouble does occur, it is often caused by improper operating procedures or by a failure in external circuitry. Often personnel who operate the amplifier are not aware of its operational capabilities, and a brief indoctrination will clear up an apparent trouble.

Ac Shunt Relay

An ac shunt relay is illustrated in figure 2-23. The basic function of the relay is to make or break an electrical control circuit when the relay coil is energized. To do this, voltage is applied to the operating coil, 2 (connected across the line), which attracts the armature, 3. When the armature is pulled down, it closes the main contacts, 4.

Testing Cables

An alternate method of ground testing multiconductor cables is to connect all conductors together and measure the insulation resistance from all conductors to ground simultaneously. If this reading is equal to or above the accepted minimum, no other reading need be taken. If the reading is below the accepted minimum, the conductors must be separated and tested individually to isolate the low-reading conductor(s).

APPARENT ROTATION OF THE GYROSCOPE

An observer on the earth's surface does not see the operation of the gyro in the same way as an observer in space does. On the earth, the gyro appears to rotate, while the earth appears to stand still. As the earth rotates, the observer moves with it, so the gyroscope seems to rotate around its horizontal axis. The effect the observer sees on the earth is called apparent rotation and also is referred to as the horizontal earth rate effect. If the gyro were started with its axle vertical at one of the earth's poles, it would remain in that position and produce no apparent rotation around its horizontal axis. Figure 4-7 illustrates the effect of apparent rotation at the equator, as seen over a 24-hour period.

Latch-In Relay

Another type of relay is the latch-in relay. This relay is designed to lock the contacts in the de-energized position until the relay is either manually or electrically reset. Two windings are used: the trip coil and the reset coil. When the trip coil is energized, it acts on a spring-loaded armature. The movable contacts of the relay are mounted on this armature. After the contacts open they are held in the open position by a mechanical latch. The mechanical latch is unlatched when the reset coil is energized, thus allowing the relay's contact to close again.

FORCE OF TRANSLATION

Any force operating through the center of gravity of the gyroscope does not change the angle of the plane of rotation but moves the gyroscope as a unit without changing its position in space. Such a force operating through the center of gravity is known as a force of translation. Thus, the spinning gyroscope may be moved freely in space by means of its supporting frame, or case, without disturbing the plane of rotation of the rotor. This condition exists because the force that is applied through the supporting frame acts through the center of gravity of the rotor and is a force of translation. It produces no torque on the gyro rotor.

Precession

Any force that tends to change the plane of rotation causes a gyroscope to precess. Precession continues as long as there is a force acting to change the plane of rotation, and precession ceases immediately when the force is removed. When a force (torque) is applied, the gyroscope precesses until it is in the plane of the force. When this position is reached, the force is about the spinning axis and can cause no further precession.

APPARENT ROTATION OF THE GYROSCOPE

Apparent rotation is illustrated by placing a spinning gyroscope with its axle on the meridian (aligned north-south) and parallel to the earth's surface at 45° north latitude and 0° longitude (fig. 4-9).

ARC CHUTE MAINTENANCE

Arc chutes should be cleaned by scraping with a file if wiping with a cloth is not sufficient. Replace or provide new linings when they are broken or burned too deeply. See that arc chutes are securely fastened and that there is sufficient clearance to ensure that no interference occurs when the switch or contactor is opened or closed.

LATITUDE CORRECTION

As a result of this tilt, the damping weight produces a vertical torque which causes the north end of the gyro axle to settle eastward from the true meridian in north latitudes, westward in south latitudes. This displacement from the true meridian, increasing with latitude, is called latitude error. In the Mark 27 Gyrocompass, latitude error is corrected by applying an opposing vertical torque to the gyrosphere of a magnitude to just cancel out the steady torque produced by the damping weight. The gyro settles with a tilt, but with no latitude error.

Sound-Powered Telephone Maintenance

As an IC Electrician, you will be required to service sound-powered telephones. Because a great deal of time is devoted to the repair of these sets, you should become thoroughly familiar with the proper methods of testing and repairing them. Many of the larger ships in the fleet have a telephone shop devoted entirely to the repair of sound-powered telephones.

EFFECT OF EARTH'S ROTATION

As just explained, a free-spinning gyroscope can be moved in any direction without altering the angle of its plane of rotation. If this free-spinning gyroscope is placed on the earth's surface at the equator, with its spinning axis horizontal and aligned east and west, an observer in space below the South Pole would note that the earth rotates clockwise from west to east and carries the gyroscope along. As the earth rotates, rigidity of plane keeps the gyroscope wheel fixed in space and rotating in the same plane at all times. Figure 4-6 shows how this gyroscope would appear. Assume that the gyroscope is set spinning at 0000 hours with its spinning axis aligned east and west and parallel to the earth's surface. At 0600, 6 hours after the gyroscope was started, the earth has rotated 90° and the axle of the gyroscope is aligned with the original starting position. At 1200 the earth has rotated 180°, while the gyroscope returns to its original position. The figure shows how the gyro completes a full cycle in a 24-hour period.

Units and Assemblies

As shown in Figure 4-50, the RLGN Cabinet consists of an upper Cabinet Assembly and a lower Measurement Cabinet Assembly, which are separated by a heat shield. The upper cabinet houses power supplies, synchro amplifiers, and rack-mounted circuit cards that contain the interface, control, and data processing circuits. The lower cabinet contains the IMU components.

PLOTTERS TRANSFER SWITCHBOARDS

As shown in figure 5-19, view B, the closing of any one of the five switches associated with each jackbox permits the jackbox to be connected to one of the sound-powered circuits. In the figure, jackbox JS 1 is shown connected to sound-powered circuit 22JS, and jackbox JS2 is shown connected to sound-powered circuit 81JS. Any of the remaining jackboxes, JS3 through JS10, may be connected to one of the five sound-powered circuits by simply closing the associated switch.

Precession

As the gyroscope precesses, it carries the weight around with it so that forces F and F1 continuously act at right angles to the plane of rotation, and precession continues indefinitely. In other words, the rotor will turn to the right and continue turning until the weight is removed.

Principles of Operation of the Transmitter Unit

As the sound waves strike the diaphragm, they cause the diaphragm to vibrate back and forth. The armature bends first to one side and then to the other, causing an alternating polarizing flux to pass through it, first in one direction and then the other. These lines of force passing through the armature will vary in strength and direction, depending upon the vibrations of the diaphragm. This action induces an electromotive force (emf) of varying direction and magnitude; that is, an alternating voltage in the coil. This alternating voltage has a frequency and waveform of the sound wave striking the diaphragm.

THREE DEGREES OF FREEDOM

As you can see in figure 4-1, the mounting of the gimbals allows movement in three separate directions, or three degrees of freedom: (1) freedom to spin, (2) freedom to tilt, and (3) freedom to turn. The three degrees of freedom allow the rotor to assume any position within the case. The rotor is free to spin on its own axis, or the X axis, the first degree of freedom. The inner gimbal is free to tilt about the horizontal or Y axle, the second degree of freedom. The outer gimbal ring is free to turn about the vertical or Z axis, the third degree of freedom.

AMPLIFIER CONTROL SWITCHES

At stations where it is desired to maintain two-way communication for all circuits serving the station, an amplifier control switch is installed. This switch provides the operator with a means of selecting anyone of several circuits to be amplified while retaining two-way communications at normal sound-powered level for other circuits not selected to be amplified. These switches are multiple rotary-type S-3R and are provided with dial illumination for darkened-ship condition areas. The incoming sound-powered telephone circuits are connected to the sound-powered telephone amplifier via this switch.

LEVELING COMPLETION

At the end of the leveling sequence, the software program calculates the alpha angle, establishes an initial value for latitude, and initializes the two direction cosines (pitch and roll angles). If a latitude entry was made at the start or during the leveling sequence, that value will be the initial latitude; otherwise, latitude is set to zero degrees.

FINE LEVELING

At the start of fine leveling, as in digital coarse leveling, all integrators, biases, and the alpha angle signal are set to zero. Again, completion of the sequence is determined by the velocity error signals. When the absolute values of these signals represent less than 1/4 ft/sec and 6 minutes have elapsed, fine leveling is completed.

ABT DEVICE

Automatic operation (refer to fig. 3-7) is accomplished when the normal supply voltage drops to the dropout range and relays 1V, 2V, and 3V drop out. Contact 1Val opens, disconnecting relay SE. After a time delay of 0.3 to 0.5 seconds, relay SE opens, closing its SEb1 and SEb2 contacts and energizing relay 4V from the emergency source. When contact 4Val closes, it connects the emergency source to coil TS of the transfer switch, which, in turn, operates, transferring the load to the emergency source.

Auxiliary Circuits

Auxiliary circuits duplicate certain principal primary circuits as an alternate means of communication in case of damage to the primary circuit. The wiring of the auxiliary circuits is separated as much as practicable from the wiring of the corresponding primary circuits to lessen the possibility of damage to both circuits. Auxiliary circuits are designated XJA through XJZ.

SELECTING THE ALIGN MODE.

Available references are determined by the installed configuration of the position and velocity references. Ship's speed reference is configured through a single-axis synchro interface, through a single-axis STANAG 4156 interface, through a serial interface by DSVL, or through an NTDS interface by GPS. Automatic position input is configured through a GPS or EC interface. The GPS interface is a configurable NTDS interface or an RS-422A NMEA 0183 Guidance Gimbal Assembly (GGA) message interface.

NORMAL POWER

BITE circuits in the control monitor continuously check the 5-volt regulator, 13-volt regulator, DC/DC module, transformer rectifier, and inverter assembly outputs for over- and under-voltage conditions. They also monitor the frequency and voltage of the 3-phase and single-phase, 115 volts ac and the power supply temperature.

FAULT INDICATORS

BITE logic circuits in the control monitor continuously monitor the 5-volt regulator, 13-volt regulator, DC/DC module, battery charger, and battery set for overvoltage and under-voltage conditions. If an under-voltage condition in the battery charger occurs, the control monitor sends a battery status signal to the control indicator, setting the BATTERY STAT indicator. If an overvoltage condition occurs in the battery charger, 5-volt regulator, 13-volt regulator, or DC/DC module, the fault indicator on the faulty card will set, and the control monitor will send a signal to the control indicator, energizing the FAULT PS indicator. The control monitor will also turn off the 5-volt regulator, 13-volt regulator, and DC/DC module when an overvoltage condition occurs. The fault indicators will remain set after the power supply is turned off. A gyro over-temperature condition, failure of the servoamplifier or gyro spin supply will also initiate no-go commands to the control monitor, which will shut down the power supply.

CABLE RACK

Banding material is five-eighths of an inch wide and may be zinc-plated steel, corrosion-resistant steel, or aluminum, depending on the requirements of the installation. For weather-deck installations, use corrosion-resistant steel band with copper-armored cables; zinc-coated steel with steel armor; and aluminum with aluminum armor.

TYPE JR

Barriers are also provided between sections to prevent terminals from turning and shorting to adjacent terminals. If the sections are not uniform, the switch will be designated by JRSP followed by the number of sections.

Rheostats and Resistors

Be certain that ventilation of rheostats and resistors is not obstructed. Replace broken or burned out resistors. Temporary repairs of rheostats can be made by bridging burned out sections when replacements are not available. Apply a light coat of petrolatum to the faceplate contacts of rheostats to reduce friction and wear. Make sure that no petrolatum is left in the spaces between the contact buttons as this may cause burning and arcing. Check all electrical connections for tightness, and wiring for frayed or broken leads. Service commutators and brushes for potentiometer-type rheostats according to instructions for the dc machines.

Precession

Because of precession, a gyro will react to the application of torque by moving at right angles to the direction of the torque. If the torque is applied downward against the end of the axle of a gyro that is horizontal, the gyro will swing to the right or left in response. The direction in which it will swing depends on the direction the rotor is turning.

TYPE JF

Because of the problems in making toggle switches watertight, it was necessary to provide a cover with a gasket for the 10- and 20-switch boxes, which contained the toggle switches. The cover had to be open when the switches were operated. Therefore, the switch box was not watertight, leading to possible malfunctioning of the switches. In addition, the lack of a strong contact wipe action in toggle switches and the low voltage and current in sound-powered circuits resulted in the formation of an insulating film on the contacts. This film resulted in open circuits or, if required, several operations of the toggle switch handle before the circuit was initially made.

RELAYS

Because the ac is going through a peak, dropping to zero, going through a peak in the opposite direction, and then dropping to zero again during each complete cycle, the coil tends to release the armature each time the current drops to zero and attracts the armature each time it reaches a peak. The shorted turn acts as the secondary of a transformer, the primary of which is the relay operating coil. The current in the shorted turn is out of phase with the current of the operating coil because the copper ring has low-inductive reactance. Thus, when the operating coil flux is zero, the flux produced by the shorted coil is different from zero, and the tendency of the relay to chatter is reduced.

RELAYS

Because the contacts of relays may open or close when energized, they can be used as protective devices or control devices or both simultaneously.

FINAL INSPECTION AND INSULATION RESISTANCE CHECK

Before returning a circuit breaker to service, inspect all mechanical and electrical connections, including mounting bolts and screws, drawout disconnect devices, and control wiring. Tighten where necessary. Give final cleaning with a cloth or compressed air. Operate manually to make sure that all moving parts function freely. Check insulation resistance.

POWER REMOVAL

Before working on a circuit breaker, control circuits to which it is connected should be de-energized. Drawout circuit breakers should be switched to the open position and removed before any work is done on them. Disconnecting switches ahead of fixed-mounted circuit breakers should be opened before any work is done on the circuit breaker. Where disconnecting switches are not provided to isolate fixed-mounted circuit breakers, the supply bus to the circuit breaker should be de-energized, if practical, before inspecting, adjusting, or replacing parts or doing any work on the circuit breaker. If the bus cannot be de-energized, observe the safety precautions of working on an energized circuit. These precautions can be found in NSTM, chapter 300.

Stuffing Tubes

Below the main deck, stuffing tubes are used for cable penetrations of watertight decks, watertight bulkheads, and watertight portions of bulkheads that are watertight only to a certain height. Above the main deck, stuffing tubes are used for cable penetrations of (1) watertight or airtight boundaries; (2) bulkheads designed to withstand a waterhead; (3) that portion of bulkheads below the height of the sill or coaming of compartment accesses; (4) flametight or gastight or watertight bulkheads, decks, or turrets or gun mounts; and (5) structures subject to sprinkling.

Bus Transfer Equipment

Bus transfer equipment should be tested weekly. For manual bus transfer equipment, manually transfer a load from one power source to another, and check the mechanical operation and mechanical interlocks. For semiautomatic equipment, the test should also include operation by the control push buttons. For automatic equipment, check the operation with the control switches.

MOTOR CONTROLLERS

By definition, a motor controller is a device (or set of devices) that serves to govern, in some predetermined manner, the operation of the dc or ac motor to which it is connected. Preventive maintenance of motor controllers should be accomplished while consulting the applicable PMS card. Troubleshooting and corrective maintenance of motor controllers is discussed in depth in Interior Communications Electrician, volume 2, NAVEDTRA 14121A.

Cable Storage and Handling

Cable storage-Cables shall be stored in a dry place protected from the weather and limited to a temperature range of not less than -40 degrees Celsius (oC) [- 40 degrees Fahrenheit (oF)] nor greater than +70oC (+158oF). It is recommended that cables be limited to a maximum temperature +30oC (+86oF). A cable that has been in storage for less than one year may be installed if a visual inspection of the cable shows no mechanical damage that would impair the watertight integrity of the cable's outer sheath or the integrity of the interior components. A conventional optical fiber cable that has been in storage for one year or longer may be installed if it passes the visual inspection and if the optical attenuation is less than the value specified. A BOF cable that has been in storage for one year or longer may be installed if it passes the visual inspection, and if a ball bearing with a minimum outer diameter of 4 mm will pass through each BOF tube within the cable. Cables shall be stored on reels with minimum diameters of 24 times the cable outside diameter, or coiled so that the bend diameter shall be not less than 24 times the cable outside diameter. Bare ends of stored cables shall be sealed against moisture using heat shrink end caps as specified herein. Terminated cables shall be sealed against moisture using connector dust covers (for multiple terminus connectors), plastic caps or heat shrink end caps as specified herein.

Cable pulling in armored cable cableways

Cableways containing armored cable should be avoided where possible. Where installation of optical fiber cables into cableways containing armored cable cannot be avoided, additional personnel shall be used to monitor during pulling due to the increased possibility for mechanical damage to the optical fiber cable.

CALL AND SIGNAL CIRCUITS

Call and signal circuits used in conjunction with a ship's sound-powered telephone system provide the means of calling and signaling between stations of the various sound-powered telephone circuits. The call and signal circuits are designated E, EM, and MJ.

UNIT 1

Call-signal station A1 consists of a cover assembly and a case assembly. The cover assembly (fig. 5-25) contains two single-pole, 12-position thumbwheel station selection switches, a PLACE CALL/ANSWER toggle switch, a side-crank dc hand-ringing generator with related electronics, and an attenuator to adjust the ring signal audio level. The case assembly is the housing for the cover assembly and contains the necessary terminal board and multi-pin connector to mate with the plug on the cover assembly. The case assembly also provides the means of connecting the handset.

Liquid-Level Float Switch

Can be found in tank- and bilge-level alarms, this float switch has a doughnut-shaped, floatable magnetic core operating over an encapsulated reed switch. The entire assembly can be mounted at any predetermined level, and the switch can be made normally open or closed by reversal of the core. Level conditions are indicated as normal, above normal, or below normal.

TYPE LS.

Can be remote or manually operated. It has provisions for six double fuseholders, contact module with up to 56 poles which can be switched from off to seven positions. This switch is constructed to withstand an excess of 30,000 operations. All LS versions have the capability of handling 10 amperes at 115 VAC, 60 HZ.

Casualty Communications

Circuit X40J is designated the casualty communication circuit. This supplementary string circuit provides a means of rigging emergency communication lines between vital stations after a casualty has occurred. This circuit applies to combatant ships and auxiliary ships, 200 feet and over in length, fitted with weapons.

Sound-Powered Headset-Chestsets

Capacitor C1 is in the circuit to prevent the flow of direct current through the receiver units when the set is used on the output side of a sound-powered telephone amplifier. When the set is used on the output side of the amplifier, a small dc voltage is placed across the set to form an amplifier squelching circuit to avoid acoustical feedback when the local set is transmitting. When the press-to-talk switch, S1, is depressed, direct current flows through the transmitter unit, causing a relay in the amplifier to operate and activate the squelching circuit.

Cartridge Fuses

Cartridge fuses are made in capacities of 1 through 1000 amperes for voltages of 125, 250, 500, 600, and 1000 volts. Fuses intended for 600- and 1000-volt service are longer and do not fit the same fuse holders intended for lower volt service. Fuses of different ampere capacity are also designed for different sizes of holders. For example, fuses of 1 through 30 amperes fit one size of holder, and fuses with capacities of 35 through 60 amperes fit a different size holder.

Cartridge Fuses

Cartridge fuses in IC equipment are of various sizes, such as the miniature FO2 or FO3 (1 1/4- by 1/4-inch) fuse rated from 0.1 to 30 amperes at 125 volts and the midget FO9 (1 1/2- by 13/32-inch) fuse rated for 0.1 through 30 amperes at 125 volts. The standard 2- by 9/16-inch fuse is rated from 1 to 30 amperes, 500 volts for ac service and 250 volts for dc service. Fuses above 60-ampere capacity have knife-blade contacts and increase in diameter and length as the capacity increases.

CASUALTY POWER DISTRIBUTION SYSTEM

Casualty power switchboard terminals are provided at switchboards as well as at some distribution panels. Portable cables can be connected at these points to obtain power from, or supply power to, the bus bars. Casualty power circuit breakers are also installed at switchboards to de-energize terminals for connecting cables.

NORMAL POWER

Certain conditions will cause the control monitor to automatically turn the gyro off. These conditions are over-temperature, power supply fault, IMU fault, and battery under voltage when operating on the battery. When automatic shutdown occurs, the control monitor turns the gyro off as if the MODE switch were turned to the POWER OFF position, with one exception. Built-in test signals are applied to the control power supply to energize the proper fault indicators and alarms.

Circuit E - Sound-Powered Telephone Call Circuit

Circuit E provides a means of signaling between sound-powered telephone stations, where not more than six stations are to be called by the calling station. The circuit operates on 120-volt, 60-Hz, single-phase power, which is usually supplied by the main IC switchboard. Watertight and non-watertight push buttons and lever-operated spring return or spring return rotary switches are provided at all calling stations. Buzzers, horns, bells, and drop-type annunciators are installed at the associated called stations. Buzzers are used in low noise level spaces. Horns are used in high noise level spaces, and bells are used in other spaces. Annunciators are provided at all stations where two or more similar audible signals are required. To use the circuit, the caller operates a switch at the calling station, which in turn energizes the audible and/or visual signal devices located at the called station.

Circuit EM - Sound-Powered Telephone Signal Circuit

Circuit EM provides a means of signaling between sound-powered telephone stations, where more than six stations are to be called by the calling station. Circuit EM is divided into the same functional circuits as circuit E except that 1EM through 5EM is used. Circuit EM uses type IC/D call signal stations, which require no external power, and provides the operator with selective calling of up to 16 individual stations.

Circuit MJ - Multiple-Talking and Selective Ringing Circuit

Circuit MJ provides a means of communication with more than one conversation on the circuit simultaneously, as well as providing selective ringing at each station. In addition, the sound-powered telephone and ringing circuits are combined to provide one common talking circuit between all stations. Up to eight separate conversations are possible at one time. The circuit may be used with any particular sound-powered circuit where its capabilities would be advantageous.

CIRCUIT BREAKERS

Circuit breakers have three fundamental purposes: to provide circuit protection, to perform normal switching operations, and to isolate a defective circuit while repairs are being made. Circuit breakers are available in manually or electrically operated types that may or may not provide protective functions. Some types may be operated both ways, while others are restricted to one mode.

Circuit Breakers, Contractors, and Relays

Circuit breakers should be carefully inspected and cleaned at least once a year and more frequently if subjected to unusually severe service conditions; that is, during ships overhaul period. A special inspection should be made after a circuit breaker has opened a heavy short circuit.

FAULT INDICATORS

Circuit cards and assemblies in the IMU are tested by a combination of hard-wired and software-monitored BITE. When either the servoamplifier or gyro spin supply circuit card fails, a hard-wired BITE fail signal is sent to the control monitor, which was discussed in the preceding paragraph. The gyro spin supply circuit card is also tested under control of the processor. The remaining circuit cards and assemblies are tested by the processor. If the processor detects a fault, a signal is sent, causing the four indicators located on the front of the IMU to set in the proper combination to indicate the faulty card. The control indicator also receives a signal, setting the FAULT IMU indicator.

Class 3

Class 3 IC systems are systems that, together with class 1 and class 2 systems are essential to complete interior control and battle circuits. Class 3 systems are energized during condition watches and operations. The switchboard plate is colored red on surface ships, and the symbol for submarines is a circle.

Class 4

Class 4 IC systems are convenience circuits. These circuits are energized only when they are required. The switchboard plate is colored white on surface ships, and the symbol for submarines is a triangle.

CLEANING BREAKER MECHANISM SURFACES

Clean all circuit breaker mechanism surfaces, particularly insulation surfaces, with a dry cloth or air hose. Be sure that water is blown out of the air hose, that the air is dry, and that the pressure is not over 30 lb/in2 before directing it on the breaker.

Maintenance of Switches

Clean burned copper contacts with fine sandpaper. Do not use emery cloth. Badly burned contacts should be replaced. Always replace contacts in pairs, rather than replacing a single contact.

Communication Interference

Communication interference while making point-to-point, conference calls, or both may occur due to cross talk and looping.

COMPUTER SWITCH CONTROL PANEL

Computer Switch Control Panel varies in size according to the Digital Switchboard it controls, and It draws its power from the Switchboard.

Emergency Switchboards

Emergency switchboards should be tested regularly, according to the instructions on the switchboard, to check the operation of the ABT equipment and the automatic starting of the emergency generator.

Flexing Service

Flexing service cable designed for use aboard ship is commonly referred to as being portable because it is principally used as leads to portable electric equipment. It is also of two types—general use and special use.

CONTACT CLEANING

Contacts in circuit breakers, contractors relays, and other switching equipment should be clean, free from severe pitting or burning, and properly aligned, Occasional opening and closing of contacts will aid cleaning and sealing. Remove surface dirt, dust, or grease with a clean cloth.

METER ASSEMBLY.

Contains AC and DC meters to monitor bus voltages and ground potentials within the switchboards.

FUSE DISPENSER

Contains a series of drawers, each marked with an appropriate fuse size. The drawers are stocked with a supply of fuses of each current rating in the switchboards. The assembly is provided with a hinged access cover.

Control Circuits

Control circuits should be checked to ensure circuit continuity and proper relay, contactor, and indication lamp operation. Because of the many types of control circuits installed in naval ships, it is impractical to list any definite operating test procedures in this manual. In general, certain control circuits, such as those for the starting of motors or motor generator sets, or voltmeter switching circuits, are best tested by using the circuits as they are intended to operate. When testing such circuits, the precautions listed in NSTM, chapter 300, should be observed to guard against damage to the associated equipment.

Control Relays

Control relays are also classified as open, semi-sealed, or sealed. Figure 2-20 illustrates the various types of relays used today. Relays E, G, and H are examples of open relays. The mechanical motion of the contacts can be observed and the relays are easily available for maintenance. Relays B, C, and F are semi-sealed relays. The covers provide protection from dust, moisture, and other foreign material, but can be removed for maintenance. Relays A and D are examples of hermetically sealed relays. These relays are protected from temperature or humidity changes as well as dust and other foreign material. The covers cannot be removed, thus making the relay tamperproof.

Control Relays

Control relays can also be used in so-called lockout action to prevent certain functions from occurring at the improper time. In some equipment, control relays are used to sense under-voltage and overvoltage, reversal of current, excessive currents, and so on.

Maintenance of Relays

Covers should not be removed from semi-sealed relays in the field. Removal of a cover in the field, although it might give useful information to a trained eye, may result in entry of dust or other foreign material that may cause poor contact or an open circuit. Removal of the cover may also result in loss of or damage to the cover gasket. When the relay is installed in a position where there is a possibility of contact with explosive fumes, extra care should be taken with the cover gasket. Any damage to, or incorrect seating of, the gasket increases the possibility of igniting the vapors.

SELECTING THE ALIGN MODE.

DOCKside is a special reference function which provides fixed position and speed input. When DOCKside is selected, the AN/WSN-7B(V) sets the reference ground speed input to zero. Reference ship's position is initialized by Manual entry. This position and zero velocity data continues to be used as the reference while DOCKside remains selected. DOCKside can only be used while the ship remains stationary (at dockside). If the ship is moving, position and speed reference other than DOCKside must be selected.

IC TEST SWITCHBOARDS

Dead-front IC test switchboards are installed in the IC shops on most ships to provide a means of performing operational tests and for troubleshooting IC components.

TERMINAL MARKING

Double-letter circuits have supply lead markings assigned as for single-letter circuits, except that the second letter of the negative is doubled; for example, positive MB, negative MBB.

Fuse Holders

Due to the design of certain fuses and in cases where space does not permit indicator-type fuse holders, separate indicator light circuits are mounted on a panel and connected in parallel with separately mounted fuses and fuse clips. In some cases an alarm circuit in the form of a bell or buzzer takes the place of the indicator light.

Cable bend diameter

During handling and installation in cableways, cable bends in optical fiber cables shall not violate the minimum short term bend diameter of the cable. The completed installation shall not violate the minimum long-term bend diameter of the cable. The installation of optical fiber cables at or below temperatures of 2oC (36oF) is not recommended. If cable must be installed when its temperature is 2oC (36oF) or lower, the cable shall be warmed thoroughly using a portable heater (or equivalent) before installing the cable in the cableway.

4JV

Engineer's circuit (fuel and stability)

Cable handling

During handling, the conventional optical fiber cable and the BOF cable shall be protected from crushing, kinks, twists, and bends that violate the minimum short term bend diameter of the cable. The minimum short-term bend diameter of conventional optical fiber cable is eight times the cable outside diameter. The minimum short term bend diameter of BOF cable is 0.13 m (5 inches) for single tube BOF cable and 0.45 m (18 inches) for seven tube BOF cable. It is recommended that cables not be handled in ambient temperatures at or below 36oF (2oC).

Overload Relays

During periodic inspections of motor controllers, or at least once a year, overload relays should be examined to determine that they are in good mechanical condition and that there are no loose or missing parts. The size of overload heaters installed should be checked to determine that they are of proper size as indicated by the motor nameplate current and heater rating table. Any questionable relays should be checked for proper tripping at the next availability and replaced. If necessary a description of the various types of overload relays can be found in NSTM, chapter 302, "Electric Motors and Controllers."

GRADED INDEX FIBER

Each layer of the core reflects light. Instead of being sharply reflected as in the step index fiber, the light is now bent or continually refracted in an almost sinusoidal pattern. Those rays that follow the longest path by traveling near the outside of the core have a faster average velocity. The light traveling near the center of the core has the slowest average velocity. As a result, all rays tend to reach the end of the fiber at the same time. Graded index fibers have core sizes of 50, 62.5, or 85 microns and a cladding diameter of 125 microns. Standard on Naval ships is the 62.5 and 125 microns.

Casualty Communications

Each repair party locker on the ship is equipped with four 200-foot lengths of type MRID-1 (commonly called salt and pepper) portable cable. Each cable has a telephone jackplug fitted at both ends and is stowed on a reel. Each repair locker also contains two sound-powered telephone headset-chestsets and eight double-gang jackboxes (with jackbox outlets connected in parallel).

Casualty Communications

Each single jackbox installed in the below-deck stations contains a nameplate that indicates the circuit identification X40J. Below-deck stations include steering gear rooms, engine rooms, emergency generator rooms, central control stations, firerooms, auxiliary machinery rooms, and IC rooms.

Linear Movement Switches

Each type of linear switch offers a number of versions designed to satisfy a particular requirement. The type designation of the switch describes its basic features. It is an alphanumeric designation and is explained in the following example:

RATINGS AND CHARACTERISTICS OF CABLES

Electrical characteristics are given under columns headed Rated Voltage and Ampacity. In the column headed CDR ID (conductor identification), the letters stand for the identification and the number stands for the method of applying the identification. There are four codes for identifying the conductors in a cable; they are STD (standard identification code), TEL (telephone identification code), SPL (special identification code), and LTR (letter identification code). Table 2-6 gives the standard identification color codes for identifying conductors in multiple-conductor cables. Table 2-7 gives the telephone identification color codes for telephone cables. Table 2-8 gives the special identification color codes for conductors and groups of conductors, such as pairs and triads. Letter identification codes consist of the letters A, B, C, and D printed in block type and with black, white, red, and green ink, respectively.

Factors Affecting Insulation Resistance

Factors that affect cable insulation resistance measurements are length, type, temperature, and the equipment connected in the circuit. Each of these factors must be evaluated to reliably determine the condition of the cable from the measurements obtained.

GPS or GPS I/O Faults

Failure of the GPS position sensor input to the INS will result in slow degradation in the accuracy of the estimate of position. Position performance degrades approximately as a function of the square root of time as shown in Figure 4-59. INS performance can be maintained by selecting a different position sensor (if configured for additional position sensor) or by periodically entering a position fix manually.

SWITCHING CIRCUIT

Figure 5-17 is a functional representation of the K1 switching circuit, showing K1 in an energized and operated condition. The receiver element of the local headset-chestset is in series with a dc blocking capacitor, thereby presenting a high resistance when the talk switch is open. Closing the talk switch connects the headset across the line, giving the headset a dc resistance of approximately 4.8 ohms. It is the function of the switching circuit to sense this change from high impedance to low resistance that takes place with the depression of one of the six headset-chestset talk switches.

Sound-Powered Handsets

Figure 5-7 is a wiring diagram of a type H-203/U sound-powered telephone handset. The non-locking, normally open, spring return, push switch, S1, disconnects the sound-powered transmitter and receiver units from the line in the open position, and connects the units to the line in the closed (depressed) position. Capacitor C1 is connected in parallel with the sound-powered units for tone compensation. When using the sound-powered handset, switch S1 must be depressed for both transmitting and receiving.

Principles of Operation of the Transmitter Unit

Figure 5-8, views B and C, show sound waves striking the diaphragm and causing the diaphragm to vibrate. The vibrations are impressed upon the armature by the drive rod. During the compression part of the wave (fig. 5-8, view B) this action causes the armature to bend and reduce the air gap at the upper south pole. The reduction of the air gap decreases the reluctance between the upper South Pole and the armature, while increasing the reluctance between the armature and the upper North Pole. This action reduces the lines of force that travel between the two upper pole pieces. There is no large change in the reluctance at the lower poles; however, the armature has less reluctance than the lower air gap and a large number of magnetic lines of force will follow the armature to the upper South Pole.

LC CONNECTORS

First marketed by AT&T, the "Low Cost" connector is significantly smaller than its counterparts. The LC uses a 1.25mm ferrule and has an RJ- 45 style push-pull housing and latching mechanism.

GENERAL USE

Flexing service cable is used as leads to portable equipment and permanently installed equipment where cables are subjected to repeated bending, twisting, mechanical abrasion, oil, sunlight, or where maximum resistance to moisture is required.

Conventional optical fiber cable minimum bend diameters

For bending radii larger than a couple of inches, macrobending losses are small and imperceptible. For bending radii less than a few inches, loss increases rapidly and becomes prohibitively large at a certain critical radii.

ABT DEVICE

For purposes of explanation, the 3-phase model will be discussed. The ABT-1A2 is designed to transfer automatically from normal to emergency supply upon a decrease in voltage to within the 81- to 69-volt range across any two of its three phases in a 120-volt system. Upon restoration of the voltage to the range of 98 to 109 volts, the unit is adjusted to retransfer to the normal source of supply. An intentional time delay of 0.3 to 0.5 seconds is included in the circuitry for both transfer and retransfer. This allows for surges in line voltage and short duration losses of power.

Gyro Motor

Gyro motor B1101 is of symmetrical design to minimize weight shifts. It consists of an outer cylindrical aluminum flywheel into which is pressed the aluminum bar squirrel cage of the induction motor. This assembly is then secured to the two aluminum endbells, and the entire unit rotates on the outer bearing races fitted into the gyro endbells. This aluminum rotor is designed for maximum angular momentum, consistent with the flotation requirements. The ball bearings and inner races of this separable bearing are fitted on a fixed aluminum shaft which also carries the stator winding of the gyro motor. The stator winding is placed at the center, and the leads are brought out through a hole bored in one end of the shaft.

LOADING HANDSET

Handsets are designed to give maximum operating efficiency when used in a 1-to-1 ratio. The number of handsets operating in parallel should in no case exceed four. Where more than four are deemed necessary from an operational standpoint, the communication should be by sound-powered headset-chestsets. To maintain the overall efficiency of the circuit, handset buttons should not be taped down for convenience, as this may overload the lines. When using the handset, you should speak in a loud, clear voice. The power of the transmitter is generated by the voice, and while shouting is not necessary, the louder the speech, the louder the message is heard in the distant handset. When a handset is not in use, it should be stowed in its holder or stowage cabinet.

IC AND ACTION CUT-OUT (ACO) SWITCHBOARDS

IC systems receive their power from a variety of sources. The majority are energized from main IC switchboards. Some IC systems receive their power from a small local IC switchboard or a local lighting power panel.

Circuit MJ - Multiple-Talking and Selective Ringing Circuit

IC/D call signal stations are used with circuit MJ. The internal wiring of each call signal station is revised and a relay and diode assembly is mounted on the selector switch of each call signal station. When the relay is de-energized, its contacts complete the circuit to the local handsets at all call signal stations on the circuit. When a caller cranks the hand-operated magneto generator at the calling station, it energizes the coil of the relay at the called station. The contacts of the relay then close to complete the circuit to the howler at the called station. At some call signal stations on the circuit, extension handsets are provided for convenience in answering incoming calls. The extension handsets are connected to the "home station" circuit MJ wires to avoid the need of setting the station selector switch to the ANSWER position, which is required to use the local call signal station handset. Figure 5-23 is an elementary wiring diagram of an MJ circuit. 5-42 UNCLASSIFIED

TERMINAL MARKING

If corresponding portions of a circuit are energized from the forward and aft IC switchboards, the suffix letters F and A are added to the ends of wire markings to indicate the switchboard from which the wire originated.

FAULT INDICATORS

If either of the heading amplifiers fail, the inverter will send a heading fail signal to light the HDG FAIL indicator on the control-indicator. If the inverter or inverter magnetics module fail during inverter operation, the inverter sends a signal to the control monitor to command a power shutdown. A failure of either the servoamplifier or gyro spin supply, located in the IMU, causes a no-go signal to be sent to the control monitor. The control monitor initiates a power shutdown and the IMU fault indicator on the control indicator to set.

OPERATING THE MK 23 MOD 0 GYROCOMPASS

If it becomes necessary to stop the compass in a heavy sea for any reason other than failure of the follow-up system, the following procedure should be used: 1. Place the power switch in the AMPL'S position. 2. 7 Wait 30 minutes, and then place the operation switch in the CAGE position. 3. Place the power switch in the OFF position.

OPERATING THE MK 23 MOD 0 GYROCOMPASS

If power to the compass fails, place the power switch in the FIL'S position and the operation switch in the CAGE position. When the power is restored, restart the compass in the usual manner.

Precession

If the plane in which the force acts moves at the same rate and in the same direction as the precession it causes, the precession will be continuous. This is illustrated by figure 4-5, in which the force attempting to change the plane of rotation is provided by a weight, W, suspended from the end of the spin axle, X. Although the weight is exerting a downward force, the torque is felt 90° away in the direction of rotation. If the wheel rotates clockwise, as seen from the weighted end, precession will occur in the direction of arrow P.

Use of Transverse Coordinates Reference System

In a gyro-stabilized platform, torque values based on the tangent (tan) and secant (sec) of latitude are used in system control loops. While the INS is a strapdown system based on ring lasers, calculations involving these functions are also used. As the INS approaches 90 degrees latitude, these values become indeterminate (approach infinity) and are no longer valid for calculations. In addition, at high latitudes, the magnitude of east/west vectors has less validity. For this reason, an alternate (Transverse) Earth coordinate's reference system is used when the INS is operating at latitudes greater than approximately 85 degrees. The Transverse north pole is located at the intersection of the geographic 180-degree meridian and the equator.

RELAYS

In general, a relay consists of a magnetic core and associated coil, contacts, springs, armature, and the mounting. Figure 2-19 illustrates the fundamental construction of a relay. When the coil is energized, the flow of current through the coil creates a strong magnetic field that pulls the armature downward to contact C1, completing the circuit from the common terminal to C1. At the same time the circuit to contact C2 is opened.

Selection of Proper Fuses

In general, fuse ratings should be approximately 10 percent above the maximum continuous connected load. In circuits, such as call bell systems and alarm systems where only a small portion of the circuit is likely to be operated at any one time, the fuse rating should be 10 percent greater than the load of one associated group of signals operated, or 15 percent of the total connected load, whichever is greater. Where the circuit incorporates branch fuses, such as those associated with the fire-control (FC) switchboards, the rating of the fuses on the IC switchboard should be 20 percent above the maximum connected load to provide sufficient margin so branch fuses will always blow before the main fuses. In no case should the fuse rating be greater than 2 1/2 times the rated capacity of the smallest cable in the circuit. If too large a fuse were used, a fire hazard would exist.

SOUND-POWERED TELEPHONE AMPLIFIERS

In high noise level areas it is often difficult, if not impossible, to hear conversations, even over the best maintained sound-powered telephone circuits. Thus, the sound-powered telephone amplifier was developed to assist communications in these vital areas. Sound-powered telephone amplifiers are installed in machinery rooms, gun mounts, missile checkout areas, flight and hangar decks, helicopter landing platforms, and other large noisy spaces. They are also installed in spaces where it is desirable to monitor incoming signals via a loudspeaker, without the use of a sound-powered telephone.

IC AND ACTION CUT-OUT (ACO) SWITCHBOARDS

In large combatant ships, there are normally two main IC switchboards. One switchboard is located in the forward IC room, and the other switchboard is located in the after IC room. This enables each system or equipment to receive its normal power supply from the nearest IC switchboard. Smaller ships may have only one main IC switchboard.

TYPES AND SIZE DESIGNATIONS OF CABLES

In most cases, the number of conductors in a cable, up to and including four conductors, is indicated by the first type letter as follows: S—single conductor; D—double conductor; T—three conductor; and F—four conductor. For cables with more than four conductors, the number of conductors is usually indicated by a number following the type letters. In this latter case, the letter M is used to indicate multiple conductor, Examples of common shipboard cable designations are as follows: LSDSGA-3— LOW smoke, double conductor, shipboard, general use, armored, conductor size approximately 3000 circular roils. LSDCOP-2— LOW smoke, double conductor, oil resistant, portable, conductor size approximately 2000 circular mils. LSMSCA-30— LOW smoke, multiple conductor, shipboard, control armored, with 30 conductors.

SOLENOIDS

In much the same way that electromotive force (emf) is responsible for current in a circuit; emf is responsible for external magnetic effects. The emf that produces the magnetic flux in a solenoid is the product of the number of turns of wire and the current through the coil. If the current is expressed in amperes, the emf is expressed in ampere-turns. From this it can be seen that a prescribed mmf can be produced by using either a few turns of large wire (high current) or many turns of small wire (low current).

TYPE J

In one position, the rotor contacts bridge segments AB and E-F, in the next position; the rotor contacts bridge segments B-C and F-G. Diagonally opposite pairs of contacts are subsequently bridged for the remaining positions.

TERMINAL MARKING

In single-letter circuits and dc supply circuits, the positive terminal is designated by a single letter, M. Similarly, an arbitrary polarity of single-phase ac circuits is designated by a single letter, M (assumed instantaneous positive). The other side (representing the opposite polarity of both dc and ac circuits is designated by double letters, MM.

SOUNDPROOF BOOTHS

In spaces where the ambient noise level at the handset location is 90 dB or more during any condition of operation, soundproof booths are installed for use with sound-powered telephone handsets. Wherever practicable, the telephone booths are installed so that the front faces away from the direction of maximum noise. The deck area under the booth will be solid or walkway grating. Only handset(s) with holder(s) and an illumination fixture are mounted inside the booth; all other associated sound-powered equipment is mounted on the outside of the booth.

Auto Cal Mode

In the AUTO CAL mode, heading is continuously slewed, completing 360° every 24 hours. The IMU heading signals are sent to the true heading converters. Also applied to the true heading converters is the alpha angle. In AUTO CAL it is set to a value representing 15° per hour. These two signals are combined in the true heading converter to develop true heading information. The output of the true heading converter is sent to the synchro signal amplifier for amplification and distribution to the ship's equipment and is sent to the A/D multiplexer for use by the processor.

Power

In the configuration described in this technical manual, the AN/WSN-7B(V) requires 115 VAC, 60 Hz or 400 Hz, 3-phase power; and 115 VAC, 400 Hz, single-phase synchro reference. An internal battery and inverter provide emergency power for operation with digital output and synchro heading and attitude output for a limited period of time in the event of failure of the ship's power input. Table 4-3 lists the major design and physical characteristics of the AN/WSN-7B(V).

Power

In the configuration described in this technical manual, the RLGN requires 115 Volts, Alternating Current (VAC), 60 Hertz (Hz), 3 phase power and 115 VAC, 400 Hz, single-phase synchro reference. An internal battery and inverter provide emergency power for operation with digital output and limited synchro outputs (vital heading and synchro velocities) for approximately 30 minutes in the event of failure of the system power.

LAMPS AND LAMP HOLDERS

Incandescent lamp holders are normally rated at 120 volts. These lamp holders use step-down transformers for ac applications or resistors for dc applications to permit use of a lower voltage rated lamp, Lamps that are rated at 120 volts are not suitable for the vibration and shock conditions encountered aboard ship.

AMPLIFIER OPERATION

Incoming signals are amplified and delivered to local headset-chestsets and loudspeakers. The volume control knob located on the face of the amplifier is used to adjust the desired headset-chestset receiver output volume. The output volume for the associated loudspeakers is adjusted locally at the loudspeakers. The circuit associated with the telephone amplifier operates under the three following conditions: 1. When the amplifier is de-energized, direct two-way communication between local and remote stations takes place at the normal sound-powered level. 2. When the amplifier is energized, incoming signals from the remote line are amplified and transmitted to the local stations and associated loudspeakers. 3. When the amplifier is energized and the talk switch of any local station is closed, the amplifier is cut out and communications between any of the local and remote stations takes place at the normal sound-powered level.

TRMS position error

Indicates the Time Root Mean Square (RMS) value of the position error, as calculated from the start time of the Performance Monitor function, as a percentage of a normalized system specification value. For an explanation of TRMS calculation method, refer to Figure 4-60.

Adjacent Installations

Inspections should not be confined to switchboard and distribution panels, but should also include adjacent installations, which may cause serious casualties. Rubber matting, located near switchboards, should be inspected for signs of deterioration, such as cracks in the material and separation at the seams. Ventilation opening located to permit water to discharge onto electrical equipment, insufficient insulation overhead to prevent sweating, need for drip-proof covers and spray shields, and location of water piping and flanges where leakage could spray onto switchboards and other gear are examples of installations that could cause casualties. Action should be initiated to have unsatisfactory conditions corrected.

OPERATING THE MK 23 MOD 0 GYROCOMPASS

Instructions for starting and stopping (securing) the compass under normal conditions are on an instruction plate (fig. 4-23). This plate is located on the front of the control cabinet. There are two modes of operation, normal and directional gyro (DG). The normal mode of operation is used for latitudes up to 75°. The DG mode of operation is used for latitudes above 75°. Normally, the compass should be started at least 2 hours before it is needed for service. For additional information on starting the compass, refer to the manufacturer's technical manual.

Testing Cables

Insulation resistance tests (ground tests) must be made periodically on IC cables to determine the condition of the cables. In addition, tests should be made when cables have been damaged, when cables have been disconnected for circuit or equipment changes, when there is evidence that a cable has been subjected to oil or salt water, and after shipboard overhauls.

TYPE OF CABLE

Insulation resistance will vary considerably with the nature of the insulating materials employed and the construction of the cable. Therefore, it is possible to determine the condition of a cable by its insulation resistance measurements only when they are considered in relation to the typical characteristics of the particular type of cable. A Resistance Test Record Card, NAVSEA 531-1 (fig. 2-47), should be used to determine if the measured insulation resistance values are above the minimum acceptable values.

Maintenance of Circuits

Insulation tests should be made using an approved megohmmeter. You should measure from each conductor to ground and between each pair of conductors. Each reading should be a minimum of 50,000 ohms of resistance; lower readings indicate a potential source of failure. Short cable runs should have a minimum resistance well above 50,000 ohms. A separate insulation test should be made for each circuit.

RELAY AND FUSE ASSEMBLY.

It allows the switchboard to respond to external commands to transfer data automatically.

TEMPERATURE OF CABLE

It is important to maintain the operating temperature of electrical equipment within their designed values to avoid premature failure of insulation. Temperatures only slightly in excess of designed values may produce gradual deterioration, which, though not immediately apparent, shortens the life of the insulation. Therefore, the temperature of the cable must be considered with the insulation resistance measurements. Consult NSTM, chapter 300, for the proper procedures for measuring the temperature of a cable.

GENERAL USE/Non-flexing Service

LSDSGA cable is one type usually found in this general use, non-flexing service. Also in this classification is the type LSMSCA cable. This cable is nothing more than watertight cable for use in interior communications, as well as in FC circuits.

(I) Intermediate

Level Maintenance (IMA) - required maintenance normally performed by Navy personnel on board tenders, repair ships, Shore Intermediate Maintenance Activities (SIMAS), aircraft carriers, and fleet support bases.

IC AND ACTION CUT-OUT (ACO) SWITCHBOARDS

Local IC switchboards are installed in various spaces to provide local control of circuits vital to the operation of the space. These switchboards are usually found in engine rooms, central control stations, steering gear rooms, and other spaces if required.

LOCAL IC SWITCHBOARDS

Local IC switchboards are type II, bulkhead-mounted, front-service, enclosed units. Terminal boards and an ABT are mounted inside the switchboard. Switches, fuse holders, and lamp holders are mounted on the door.

JL

Lookouts circuits

Looping

Looping is an undesirable and unintentional formation of a complex series-parallel circuit among stations that are simultaneously busy. This is a result of a direct connection between terminal stations when an excessive number of simultaneous point-to-point calls are being made.

INSPECTION AND CLEANING

Loose electrical connections or mechanical fastenings have caused numerous derangements of electrical equipment. Loose connections can be readily tightened, but it requires thorough inspection to detect them. Consequently, at least once a year and during each overhaul, each switchboard, propulsion control cubicle, distribution panel, and motor controller should be de-energized for a thorough inspection and cleaning of all bus equipment. Inspection of de-energized equipment should not be limited to visual examination but should include touching and shaking electrical connections and mechanical parts to make sure that the connections are tight and mechanical parts are free to function. Where space permits, a torque wrench should be used when tightening bolts. Over-tightening can be detrimental as under-tightening. Refer to NSTM, chapter 075, "Fasteners," for torquing procedures and precautions. Table 3-2 contains torque values for the more common bolt sizes used in switchboard construction. Torque values are minimum and should not be exceeded by more than 10 percent.

LOSS OF SENSITIVITY

Loss of sensitivity, or weakening of the transmission sound, is a gradual process and seldom is reported until the set becomes practically inoperative. When a sound-powered telephone is in good condition electrically yet the sound is weak you should replace the transmitter unit. If this procedure does not remedy the trouble, then you should replace the receiver units.

MT-RJ CONNECTORS

MT-RJ is a duplex connector with both fibers in a single polymer ferrule. It uses pins for alignment and has male and female versions. Multimode only, the MT-RJ is usually pre-polished and spliced in place.

Maintenance of Gyrocompasses

Maintenance should not be undertaken by inexperienced personnel without close supervision of a qualified maintenance technician.

Fuses

Make sure that fuses are the right size and that they make firm contact with fuse clips. Ensure that lock-in devices (if provided) are properly fitted and that all fuse wiring connections are tight.

1JV

Maneuvering and docking circuit

SYNCHRO ANGLE METER ASSEMBLY

Measures the inputs and outputs of the synchro signal converter assemblies

Mechanical Switches

Mechanically operated switches are used in many types of installations, such as wrong direction alarms and valve-position indicators.

There are six methods of applying identification to the conductors of a cable. They are as follows:

Method 1—calls for printing of the number and color designation on the outer surface of the insulation or jacket of each conductor. Method 2—calls for the use of opaque white polyester tapes that have been printed with both the number and color designation prior to application. Method 3—calls for the use of solid colors or solid base colors with tracers as required. Method 4—calls for the use of colored braids. Method 5—calls for the use of the printed letter on the outermost insulating tape or the printed letter on a polyester binder tape over the insulating tape. Method 6—calls for numerals to be printed in ink on the insulation of the conductor.

ABT DEVICE

The ABT-1A2 (fig. 3-6) has a control disconnect switch that allows the ABT to be operated in the manual or automatic mode. It also has a manual switch for selecting the normal or emergency power sources and a test switch.

Lever-Operated Switches

Most lever-operated switches use JR interiors (fig. 2-12). These switches are operated by a lever with a suitable locking plate. In the interests of standardization, two types of interiors are available, each containing three 2JR sections. One type is the JRM-300, which has a spring return mechanism; and the other type is the JR-304, which has a positive detent mechanism. Through slightly different arrangements of pins, lever, and locking plate, various types of switches can be obtained.

SELECTOR SWITCHES

Most of the switches are installed with a sound-powered telephone handset permanently connected to the rotor contacts. Where a handset is not provided, the switch operator must insert a sound-powered telephone headset-chestset plug into the jack outlet. Switches located in normally darkened-ship condition areas are provided with dial illumination.

PROTECTIVE DEVICES

Most protective devices are designed to interrupt the power to a circuit or unit under abnormal conditions, such as short circuits, overloads, high or low voltage, and excessive current. The most common types of protective devices are fuses, circuit breakers, and overload relays.

Rotary Snap Switches

Most snap switches are suitable for 450-volt, 60-Hz ac and 250-volt dc operation. Present 10- ampere switches are suitable for 120-volt operation only, although the switches are sometimes used at higher voltages where the currents are very small. Care must be exercised in the application of Multi-throw (double-throw and triple-throw) switches. The movable blade, in some cases, is so wide that in moving from one stationary contact to a second, the two stationary contacts will be momentarily bridged by the arc and movable blade, causing a short circuit. Therefore, each time a multi-throw switch is to be installed, a careful check should be made on both the switch and the intended circuit to make sure that a switch of the proper current and voltage ratings is used.

SELECTING THE ALIGN MODE.

NOTE: The AN/WSN-7B(V) will use last Lat and Lon from NVRAM when the system is turned on again if the system has run (with no faults which prevent NVRAM update) for at least one hour at last power-up.

SYNCHRO OVERLOAD TRANSFORMERS AND INDICATORS

NOTE: Operation of an ACO transfer switch normally causes the associated overload indicator light to flash. This is due to a momentary displacement between the transmitter and receiver. The flash is normal and shows the system is operating properly.

FC CONNECTORS

Named FC for "field connector," it was originally devised by Nippon Telephone and Telegraph (NTT) for telecommunications. It was used by MCI in its fiber optic telephone network in the 1980s. The connector has a threaded coupling feature similar to the SMA for use in high-vibration environments. The threads would be difficult to over tighten because stops have been installed to obtain repeatable torque. It also offers a keying feature similar to the ST, except that some FC connectors are "tunable." The term "tunable" means the keying slot can be rotated to find optimal alignment and will remain in that alignment until moved again. The FC connector is available for single-mode and multimode applications. Refer to 2-115.

SC CONNECTORS

Named SC from "subscriber connector," it was also developed by NTT and gained popularity throughout the 1990s for both single-mode and multimode applications. They use a push-pull engagement for mating and are designed to be pull- proof so a slight pull on the cable will not disengage the connection. The SC connector is a strong competitor to the FC and ST connectors due to the ease in constructing multi- fiber connectors for duplex configurations. Connectors such as the FC, ST, and SMA that require twisting are not readily adaptable to multi-fiber connections in high-density applications because of the space required to allow rotation. Many experts agree that the SC is "the connector of the future." AMP has already developed a mini SC for even higher density applications. Refer to figure 2-116.

FDDI CONNECTORS

Named after the Fiber Distributed Data Interface (FDDI) Networks that ANSI designed them for, the FDDI is a duplex connector consisting of two 2.5 mm ST style ceramic ferrules.

BICONIC CONNECTORS

Named for their conical shape, many items of equipment installed during the 1980s still require interfacing using Biconic connectors. These were the first connectors used on single-mode fibers, although, they are available for singlemode or multimode applications. Biconic connectors are not keyed and early problems developed with repeatability and crushing due to over tightening. Later versions of Biconic connectors were available with a keying feature. Refer to figure 2-114.

Casualty Communications

On aircraft carriers, four-gang jackboxes are installed port and starboard on the forward and after sides at each hangar division door. The respective forward and after jackboxes are permanently connected and are used to facilitate patching when the doors are closed.

Rigidity of Plane

Newton's first law of motion states that a body in motion continues to move in a straight line at a constant speed unless acted on by an outside force. Any point in a spinning wheel tries to move in a straight line but, being a part of the wheel, must travel in an orbit around its axle. Although each part of the wheel is forced to travel in a circle, it still resists change. Any attempt to change the alignment or angle of the wheel is resisted by both the mass of the wheel and the velocity of that mass. This combination of mass and velocity is the kinetic energy of the wheel, and kinetic energy gives the rotor rigidity of plane. Gyroscopic inertia is another term that is frequently used interchangeably with rigidity of plane.

Non-flexing Service

Non-flexing service cable designed for use aboard ship is intended for permanent installation and is commonly referred to as such. Cables for use with lighting and power circuits are intended for this non-flexing service. This non-flexing service can be further classified according to its application and is of two types-general use and special use.

GENERAL USE

Non-flexing service cable is intended for use in nearly all portions of electric distribution systems, including the common telephone circuits and most propulsion circuits. Special cases occur in dc propulsion circuits for surface ships. In those cases where the impressed voltage is less than 1000 volts, an exception is permitted.

Indications of Normal Operation

Normal operating conditions for the compass are indicated by the following: 1. The follow-up failure and corrector failure lamps on the control panel should be dark. 2. The master unit should be lukewarm. 3. The speed dial should indicate the ship's speed for normal operation or zero for directional gyro operation. 4. The tilt indicator pointer should be oscillating evenly about the zero position.

APPARENT ROTATION OF THE GYROSCOPE

Now assume that the spinning gyroscope, with its spinning axis horizontal, is moved to the North Pole (fig. 4-8). To an observer on the earth's surface, the gyroscope appears to rotate about its vertical axis. To an observer in space, the gyroscope axle appears to remain fixed, and the earth appears to rotate under it. This apparent rotation about the vertical axis is referred to as vertical earth rate effect. It is maximum at the poles and zero at the equator.

TERMINAL MARKING

Numbers following the circuit letter indicate a serial number assigned for the station, followed by the section wire number designating the function of the circuit. On systems containing synchros, the numerals 1, 2, and 3 are used for the connections to secondary windings. Where more than one synchro is employed in a single instrument, the numerals 4, 5, and 6 apply to the second synchro, and 7, 8, and 9 to the third synchro. For example, l-MB 14 should be interpreted as follows: 1—starboard circuit MB—engine-order system 1—station number, such as pilot house 4—connection to secondary windings of the No. 2 synchro receiver in the instrument

TYPE BLS.

Offers three switching actions with up to four positions, remote operation, 98 available poles with 93 wired-load switching poles. Complying with the linear switch specification, the BLS is built to withstand an excess of 30,000 operations. It has provisions for 12 fuses in six, front-mounted double fuseholders. The current handling capability is 4 amperes at 115VAC, 60 Hz.

USE OF OIL

Oil should always be used sparingly on circuit breakers, contractors, motor controllers, relays, and other equipment, and should not be used at all unless there are specific instructions to do so or oil holes are provided. If working surfaces or bearings show signs of rust, the device should be disassembled and the rusted surface carefully cleaned. Light oil may be wiped on sparingly to prevent further rusting. Oil has a tendency to accumulate dust and grit, which may cause unsatisfactory operation of the device, particularly if the device is delicately balanced.

Thermal Time Delay Relay

One common form of time delay relay uses a lag coil, which is usually a large copper slug located at one end of the winding or a tubular sleeve located between the winding and the core. The lag coil (slug) acts as a short-circuited secondary for the relay coil. The counter magnetomotive force (mmf), due to the current induced in the coil by the changing coil current, delays the flux buildup or decay in the air gap and hence the closing or opening of the armature. A short slug near the armature end of the core has relatively more effect on the operating time, and one at the heel end has more effect on the release time.

Paralleling of Circuits

One disadvantage of paralleling circuits is overloading transmitters. Each sound-powered telephone receiver unit consumes electrical energy when converting transmitted electrical signals to audible signals. As receiver units are added, the demand for electrical energy may exceed the capability of the transmitter unit, resulting in the transmitter becoming overloaded. An overload condition reduces the input electrical energy available to each receiver unit, with a corresponding reduction in receiver output volume. The reduced audio output may render the circuit ineffective. The number of receivers it takes to overload a circuit varies; therefore, the controlling station should be alert to garbled messages or frequent requests for repeats, indicating the circuit is overloaded.

Amplifier Maintenance

One procedure that has caused some failures in the amplifier is the practice of taping closed the talk button of one of the local headset-chestsets. This violation of circuit integrity will result in K1 being continually restored, resulting in no amplification of incoming signals.

GRADED INDEX FIBER

One way to reduce modal dispersion is to use graded index fibers. Graded index fiber has numerous concentric layers of glass resembling the rings of a tree. Each ring outward from the central axis of the core having a lower IOR than the previous one. Light travels faster in a lower index of refraction. So, the further the light travels from the center of the axis, the greater its speed.

Installation of Optical Fiber Cables in Cableways Cable pulling

Optical fiber cables shall be installed by feeding the cable through the cableway in a segment by segment fashion for the entire route and then securing it into the cableways. Block and tackle, chain falls, or other mechanical devices shall not be used to pull optical fiber cable. The cable shall be pulled to avoid kinking, twisting, sharp bending, or stretching by applying excessive pulling force. The optical fiber cable should be monitored at all bend points and at multiple points on long straight runs to ensure that the cable does not encounter sharp objects. It is recommended that the cable be pulled slowly, so that if it does get caught, it will be readily noticeable and cable pulling can be stopped before any damage occurs.

Fiber Coating

Optical fibers used in the outside plant are usually coated with a thin layer of acrylate, which is usually 250 microns in diameter. The acrylate coating provides limited protection and color coding. Several coated fibers are then placed into breakout, distribution, or loose tube cable, depending on the application. Loose tube configurations allow the fibers to be slightly longer than the confining tubes to prevent strain damage during installation.

Conventional optical fiber cable minimum bend diameters

Optical fibers would not be practical transmission media if their ability to guide light required them to be kept perfectly straight. It must be realized that any deviation from perfect straightness causes some light to scatter into the cladding and be lost. Such deviations can occur in two ways; via large bends that can be seen by the human eye, called macrobends, and by microscopically small deviations in the fiber axis, called microbends.

FIBER OPTICS

Optics is the scientific study of light, its composition, how it travels, its effect on objects, and how it enables us to see. Fiber optics is the technique of transmitting light or images through a particular configuration of glass or plastic fibers.

Display Control Subsystem (DCS)

The DCS is the Human-Machine Interface (HMI) subsystem of the AN/SSN-6 system. The DCS is located in the chart room on most ships. The user controls the AN/SSN-6 system by using the DCS video screen, trackball, and keyboard.

Pile Switches

Pile switches are constructed so they open or close one or more electrical circuits. The contacts are arranged in leaf, or pileup, fashion and maybe actuated by a rotary, pushing, or sliding motion. The various basic forms of the contact arrangements in pile switches are shown in figure 2-6, view A. These basic forms are used by themselves or in combination to makeup the contact assembly of a pile switch. View B of figure 2-6 shows a contact assembly made by combining two break-make contact arrangements to make form C. This switch is, therefore, designated 2C. When the armature is moved upward by the rotary motion of the cam lobe (fig. 2-6, view B), two circuits are opened and two are closed. This type of switch is commonly used in relays, key switches, and jacks in low-voltage signal circuits.

PLOTTERS TRANSFER SWITCHBOARDS

Plotters transfer switchboards are found in areas aboard ship, such as the CIC, where the tactical situation governs the sound-powered circuit to which the plotters are to be connected. For instance, the situation may require that the CIC plotters connected to jackboxes JS1 through JS5 be connected to circuit 21JS, while the plotters connected to jackboxes JS6 through JS10 be connected to circuit 22JS. Another situation may call for an entirely different arrangement.

Point-to-Point Calls

Point-to-point calls can be made from any terminal station to any other terminal station. To initiate a point-to-point call, you should perform the following procedures: 1. Set the PLACE CALL/ANSWER switch to the PLACE CALL position. 2. Select the desired station number on the thumbwheel switches. 3. Remove the handset from its holder, depress the handset press-to-talk switch, and listen for talking on the line. If the line is clear, continue to step 4. If the line is not clear (busy), return the handset to its holder, and set the PLACE CALL/ANSWER switch in the ANSWER position. 4. Turn the crank several times to ring the desired station. 5. Talk to the desired station. After the call is completed, return the handset to its holder, and set the PLACE CALL/ANSWER switch to the ANSWER position.

SELECTING THE ALIGN MODE.

Position fixes can also be entered manually by the operator. Four position references sources may be used for aligning the system. These are GPS, EC, manual entry of a position FIX entry through the operator panel, and DOCKside. The Sensor menus provide operator selection of velocity reference and position reference.

Power Relays

Power relays, also known as contractors, use a relatively small amount of electrical power to control the switching of a large amount of power. The relay permits you to control power at other locations in the equipment, and the heavy power cables need be run only through the power relay contacts.

Precession

Precession describes how a gyro reacts to any force that attempts to tilt or turn it. Though vector diagrams can help explain why precession occurs, it is more important to know how precession affects gyro performance.

Control Circuits

Protective circuits, such as over-current or reverse current circuits usually cannot be tested by actual operation because of the danger to the equipment involved. These circuits should be visually checked and, when possible, relays should be operated manually to make sure that the rest of the protective circuit performs its desired functions. Exercise extreme care not to disrupt vital power service or damage electrical equipment. Reverse power relays should be checked under actual operating conditions. With two generators operating in parallel, the generator whose reverse power relay is to be checked should be made to take power from the other generator. The reverse power relay should trip the generator circuit breaker in 10 seconds or less after the reverse power relay starts to operate. If the relay fails to function, the generator circuit breaker should be tripped manually to prevent damage to the prime mover. To make a generator act as a load, it is necessary to restrict the flow of steam or fuel. This can be accomplished by reducing the speed control setting slowly until the generator begins to absorb power and act as a motor.

SOLENOIDS

Solenoids are electromagnets formed by a conductor wound in a series of loops in the shape of a helix (spiral), Inserted within this spiral or coil is a soft-iron core and a movable plunger. The soft-iron core is pinned or held in position and therefore is not movable. The movable plunger (also soft iron) is held away from the core by a spring when the solenoid is de-energized (fig. 2-27).

Maintenance of Relays

Relays are some of the most dependable electromechanical devices in use; but like any other mechanical or electrical device, they occasionally wear out or become inoperative.

Maintenance of Switches

Remove dirt and grease from switch and relay contacts with a cloth moistened with an approved solvent. No lubricants of any kind should be applied to the contacts. Use a burnishing tool for dressing small light contacts.

Rotary Selector Switches

Rotary selector switches may perform the functions of a number of switches. As the knob or handle of a rotary selector switch is rotated, it opens one circuit and closes another. In figure 2-7, the contact is from A to E. If the switch is rotated clockwise, as viewed, the circuit from A to E is opened and the circuit from A to D is completed. Some rotary switches have several layers of pancakes or wafers. With additional wafers, the switch can operate as several switches. Oscilloscope and voltmeter selector switches are typical examples of this type. These switches are more common in civilian equipment than in military hardware.

Rotary Snap Switches

Rotary snap switches are devices that open or close circuits with a quick motion. A type SR rotary snap switch (fig. 2-4) consists of one or more sections, each of which has a rotor and a stationary member. Movable contacts are mounted on a bushing, and stationary contacts are mounted on insulated disks, which are arranged one beneath the other in pancake style along the switch shaft. This type of construction has the advantages of shock-proofness, compactness, flexibility of circuit arrangements, and protection to the operator. The operator, by rotating the switch handle, triggers a spring and cam arrangement, which, in turn, operates the switch contacts. If the spring should break, further rotation of the handle will eventually cause a projection on the shaft of the handle to contact a projection on the operating shaft to operate the switch. However, the switch-driving shaft and handle will be misaligned from its normal position, and the characteristic snap action will not be apparent.

SMA CONNECTORS

SMA (Sub-Miniature, Type A) Connectors, originally designed by Amphenol, use a threaded coupling nut without a keying device. The two basic types are the 905 style and 906 style. The 905 uses a straight ferrule and the 906 has a stepdown nose to allow use of plastic alignment bushings for maximum alignment. Originally designed with a steel ferrule for multimode applications, they are now available with ceramic ferrules for single-mode applications. The primary problems that arise with the use of SMA connectors are crushing due to over tightening of the threads, and repeatability of alignment because of the lack of a keying device. Refer to figure 2-118.

ST CONNECTORS

ST (Single Terminus) Connectors were designed by AT&T Bell Laboratories for use with single-mode or multimode fibers. They use quick-release keyed bayonet couplings that are preferred in situations where severe vibrations are not expected. The ST is probably the most popular and widely used connector in local area networks, premise wiring, test equipment and other applications. The keying feature ensures that the fiber is always inserted to the mating bushing with the same orientation. The bayonet coupling prevents crushing due to over-tightening. Refer to figure 2-117. ST Connectors are the most commonly used fiber connectors in Navy applications.

Supplementary Circuits

Supplementary circuits provide the means of communication for various subordinate control, operating, and service functions. Supplementary circuits are designated X1J through X61J and are normally string circuits.

Multimode

STEP INDEX FIBER. Multimode step is the simplest type. It has a core diameter from 100 microns to 970 microns and it includes glass, PCS and plastic construction. The step index fiber is the widest ranging, although not the most efficient in having high bandwidth and low losses. Since the light reflects at different angles for different paths, the path lengths of different modes are different. Thus, different rays take a shorter or longer time to travel the length of the fiber. The ray that goes straight down the center of the fiber core without reflecting arrives at the other end faster than those rays that take a different or longer route. Therefore, light entering the fiber at the same time will exit the other end at different times. This spreading of light over time is called modal dispersion.

SEALING SURFACE

Sealing surfaces of circuit breaker, contactor, and relay magnets should be kept clean, and relay magnets should be kept clean and free from rust. Rust on the sealing surfaces decreases the contact force and may result in overheating of the contact tips. Loud humming or chattering will frequently warn of this condition. Light machine oil wiped sparingly on the sealing surfaces of the contactor magnet will aid in preventing rest.

Maintenance of Gyrocompasses

Ships having the Planned Maintenance System (PMS) installed should perform gyrocompass maintenance requirements as indicated on the equipment maintenance requirement cards (MRCs).

Maintenance of Relays

Should an inspection determine that a relay has exceeded its safe life; the relay should be removed immediately and replaced with another of the same type. The replacement relay must have the same characteristics or ratings, such as voltage, amperage, type of service, number of contacts, or continuous or intermittent duty.

FLEXIBLE PARTS

Shunts and flexible connectors that are flexed by the motion of moving parts should be replaced when worn, broken, or frayed.

TERMINAL MARKING

Signal contacts should be connected to the positive (single-letter connection) in the instruments. The section-wire markings for bell or visual signal circuits should be assigned the next higher number after assignment of numbers to secondary windings of all synchro receivers in the instruments. For example, in an instrument containing two synchro receivers the signal circuits should be assigned section wires No. 7, 8, and so on.

CONTACT CLEANING

Silver alloy contacts should not be filed or dressed unless sharp projections extend beyond the contact surface. Such projections should be filed or dressed only to the contact surface. When cleaning and dressing contacts, maintain the original shape of the contact surface and remove as little material as possible.

Maintenance of Switches

Silver contacts require very little maintenance. Removal of the tarnish that forms on silver contacts due to arcing is no longer recommended, as this blackened condition improves the operation of the contacts.

NORMAL POWER

Single-phase, 115-volt ac ship's power is applied to the gyro by an EMI filter, a relay, and the SYN REF (synchro reference) circuit breaker. The single-phase, 115 volts ac provides power for the inverter magnetic module, internal resolver reference, and a vital heading reference output.

Rotary Snap Switches

Snap switches are available in a wide variety of amperage ratings (from 10 to 200), poles, and mountings (bulkhead or panel mounting).

Uses of Solenoids

Solenoids are used for electrically operating hydraulic valve actuators, carbon pile voltage regulators, power relays, and mechanical clutches. They are also used for many other purposes where only small movements are required. One of the distinct advantages in the use of solenoids is that a mechanical movement can be accomplished at a considerable distance from the control. The only link necessary between the control and the solenoid is the electrical wiring for the coil current.

Maintenance of Relays

Some relays are equipped with ball-shaped contacts which, in many applications, are superior to the flat contacts. Dust or other substances do not collect as readily on a curved surface. In addition, a ball-shaped contact can penetrate film more easily than a flat contact. Figure 2-25, view B, shows a set of ball-shaped contacts.

Sound-Powered Telephone Maintenance

Sound-powered handsets are usually repaired on location because they are permanently connected. When trouble develops in a sound-powered headset-chestset, the usual procedure is for the operator to bring it to the IC shop and exchange it for a good one. This procedure provides each station with properly operating sets at all times. The IC shop should maintain a log of all sets turned in; this will aid in locating faulty circuits or identifying operators who continually abuse their sets.

Sound-Powered Headset-Chestsets

Sound-powered headset-chestsets are designed for general use and for use with sound-powered telephone amplifiers. Figure 5-10 is an illustration of a type H-200/U sound-powered telephone headset-chestset. This head-set-chestset consists of two sound-powered receiver units with protective shells and ear cushions, one sound-powered transmitter unit with protective shell and a push switch, one mouthpiece, one chestplate assembly with junction box provided with capacitors and terminal facilities, one headband assembly and neck strap, and one cord assembly and plug. The receivers are mounted on the headband; the transmitter is mounted on the chestplate.

SOUND-POWERED TELEPHONE AMPLIFIERS

Sound-powered telephone amplifiers amplify one-way communications in a two-way sound-powered telephone system using existing sound-powered headset-chestsets; that is, amplify the voice to the high noise level area but not the voice from it. The amplifiers accept one incoming circuit for amplification and are capable of transmitting the amplified signal to as many as six headset-chest sets and two loudspeakers.

Sound-Powered Handsets

Sound-powered telephone handsets are designed for general use on a line with other handsets or headset-chestsets. Figure 5-6 is an illustration of a type H-203/U sound-powered telephone handset and handset holder. This type of handset has a non-kinking retractable cord. Another type of handset is the H-203/U (modified). This handset is identical to the type H-203/U except that the handset cord is straight and contains no less than two conductors in a single shield. The H-203/U (modified) is modified to meet security requirements of the ship's communication center.

SOUND-POWERED UNITS

Sound-powered telephone headset-chestset receiver units will transmit as well as receive. In the event the transmitter becomes defective, and the set cannot be repaired at once, communication can still be maintained. Remove either one of the receiving units from the headband and use it as a transmitter. Since the receivers are connected in parallel, either one can be used as the transmitter.

LOADING HEADSET-CHESTSETS

Sound-powered telephone headset-chestsets are designed to operate with 10 sets in parallel without any noticeable effect in response. However, it is possible to parallel up to 20 sets before overall line level response is considered critical. To maintain the overall efficiency of the circuit, do not tape down the transmitter button for convenience, as this may overload the circuit. When using the headset-chestset, hold the press-to-talk switch down firmly to ensure good contact, and talk directly into the transmitter. When listening, be sure to release the press-to-talk switch to eliminate the pickup of extraneous sounds and also the loss in receiver signal strength due to the low impedance transmitter shunted across the line.

Maintenance of Gyrocompasses

Such routine maintenance should not be recorded in the service record book. Repairs or replacement of parts resulting from such maintenance, however, should be recorded to aid those involved with future repairs to the gyrocompass.

SWITCHBOARD MAINTENANCE

Switchboard preventive maintenance will be accomplished according to the applicable MRCs. Corrective maintenance and troubleshooting will usually consist of clearing grounds, repairing open circuits, tightening loose connections, and finding the cause for blown fuses and overloads.

Physical and Electrical Characteristics

Switchboards are generally made in two configurations. However, size is determined by the required number of switches and supporting panel assemblies.

Switchbox Circuit

Switchboxes contain either 10 or 20 switches and function primarily as small action cutout (ACO) switchboards. Switchboxes are normally located at the station having operational control over the circuit or circuits concerned. Usually, there is only one circuit in a switchbox.

Maintenance of Switches

Switches should be checked periodically to ensure that all electrical connections and mechanical fastenings are tight. Lock-washers must be in place. Avoid over-tightening the packing and nut on watertight rotary switches, as excessive pressure on the switch shaft will cause improper positioning of the switch.

RATINGS AND CHARACTERISTICS OF CABLES

Table 2-5 shows the ratings and characteristics of various cables that are included in Military Specification MIL-C-24643. Each cable is identified by the MILSPEC and specification sheet number, followed by the cable type designation, conductor size (AWG or MCM), number of conductors, conductor cross-sectional area (circular mils), overall diameter of the cable, cable weight per foot in approximate pounds, minimum radius of bend (which is approximately 8 times the overall diameter), conductor identification, rated voltage, ampacity (current-carrying capacity in amperes) of each conductor, and the national stock number (NSN).

General Equipment Function

Table 4-13 lists the major design and physical characteristics of the AN/WSN-7(V) RLGN. The RLGN requires external ship's speed input and periodic input of position data. The RLGN uses ship's log speed or velocities obtained from a GPS or DSVL to provide damping of vertical gyro loops. Position data from a GPS is used to calibrate gyro drifts and to provide position resets to the inertial navigation function. The inertial reference, speed, and filtered position reset data are processed to generate continuous and accurate position and velocity data in addition to heading, roll, and pitch reference. The RLGN transfers data to and from Battle Force Tactical Trainer (BFTT) equipment via the Asynchronous Transfer Mode (ATM) interface.

IC/N Thermostatic Switches

Temperature-operated switches are used with the circulating-water, high-temperature alarm system; cruising-turbine exhaust alarm system; and generator-air, high-temperature alarm system. Figure

PANEL 2

The 120-volt, 3-phase, 60-Hz bus located in panel 2 receives its power from panel 1 via a bank of three 450/120-volt, 60-Hz, single-phase transformers located in panel 2. This panel disseminates both 120-volt, single-phase, 60-Hz, and 120-volt, 3-phase, 60-Hz power to various IC and FC systems as required. A voltmeter, an ammeter, and a megohmmeter are installed on the front of panel 2 for monitoring by watch standers and maintenance personnel.

TYPE JR

The 1JR switch has only one movable contact per section. This movable contact bridges two adjacent stationary contacts.

TYPE JR

The 2JR switch has two movable contacts per section, 180° apart. Each movable contact bridges two adjacent stationary contacts.

PANEL 1

The 450-volt, 3-phase, 60-Hz bus located in panel 1 is energized from one of three power sources (normal, alternate, or emergency). Power becomes available through the use of two mechanically interlocked switches and an automatic bus transfer (ABT) device located in panel 1. An indication of the power available is provided through the use of indicator lights connected via transformers to each power source. On some of the newer ships in the fleet, the ABT is located separate from the switchboard itself.

TYPE JR

The 4JR switch is designed as an either or both switch with two movable contacts per section. Each movable contact bridges three adjacent stationary contacts. This switch is used to select either or both of two indicators or synchros. The positions for energizing two indicators are as follows: 90° right—both indicators energized. 45° right—indicator 1 energized only. 0°—off. 45° left—indicator 2 energized only.

ABT DEVICE

The ABT device used with IC switchboards transfers the load from the preferred source of supply if it fails to an alternate source that remains energized. When the preferred source is restored, the load is then transferred back to the preferred source automatically by the ABT device. ABTs are designed for use in ac or dc, and 60- or 400-Hz systems.

Action Cut-out (ACO) Section

The ACO section (panels 5 and 6) permits isolation of damaged portions of certain IC systems and, in addition, allows transfer control of certain systems from one station to another. Drawout switch units (fig. 3-5) are used, with each unit incorporating the associated JR switch, fuse holders, synchro overload transformers, and overload indicators.

4.12.0 AN/SSN-6(V)2 NAVIGATION SENSOR SYSTEM INTERFACE SYSTEM

The AN/SSN-6 Navigation Sensor System Interface (NAVSSI) System is an integrated shipboard system that automatically accepts, processes, and disseminates navigation and time information from various shipboard navigation sources.

4.12.0 AN/SSN-6(V)2 NAVIGATION SENSOR SYSTEM INTERFACE SYSTEM

The AN/SSN-6 is composed of three units: the Display Control Subsystem (DCS), the Real Time Subsystem (RTS), and the Bridge Work Station (BWS). The DCS provides overall system control, data processing, data storage, and Man-Machine Interface (MMI) for both operation and maintenance. The DCS also houses the Sensor Interface Unit (SIU) for processing depth below the keel sonar signals from the AN/UQN-4. The DCS monitor can be utilized as a backup to the BWS. The RTS is the primary means for communicating between the various sensors to obtain inputs for the AN/SSN-6 and to provide usable output information to various ships systems. The BWS provides parallel operator control, query, and readout of the DCS.

4.12.0 AN/SSN-6(V)2 NAVIGATION SENSOR SYSTEM INTERFACE SYSTEM

The AN/SSN-6 provides a means for users to obtain data verification, digital mapping, and the programming of selected way points. The AN/SSN-6 utilizes inputs from the Inertial Navigation System (INS), AN/UQN-4 Sonar Sounding Set, and EM Log to provide extremely accurate position (latitude and longitude), velocities (N-S, E-W, and vertical), ownship heading (OSH), roll, pitch, depth below keel, speed through the water (OSS), own ships distance (OSD), and extremely accurate time. The AN/SSN-6 also receives GPS satellite data via two embedded GPS VME Receiver Cards (GVRC).

WATCH STANDING

The AN/WSN-2 operates unattended after a mode of operation has been selected and the automatic alignment sequence is completed. Audible and visual extension alarms will alert watch standers at various locations upon loss of normal power to the compass or if a malfunction exists within the compass.

Equipment Description

The AN/WSN-2 stabilized gyrocompass set (fig. 4-34) consists of an electrical equipment cabinet and five major assemblies. The five major assemblies are contained within the cabinet. These assemblies are the control indicator, control power supply, battery set, synchro signal amplifier, and inertial measuring unit (IMU).

AN/WSN-2 STABALIZED GYROCOMPASS SET

The AN/WSN-2 stabilized gyrocompass set provides precision analog dual-speed roll, pitch, and heading signals to the ship's navigation and fire control systems. The set uses an accelerometer controlled, three-axis, gyro-stabilized platform to produce vital heading synchro data and reference, nonvital heading synchro data, and both roll and pitch angle synchro data.

Configurations

The AN/WSN-7(V) INS is available in three configurations. CN-1695/WSN-7(V) is installed on selected surface combatants. CN-1696/WSN-7(V) is installed on selected cruisers and LHA-1 class ships. CN-1697/WSN-7(V) is installed on aircraft carriers and LHD-1 class ships.

RING LASER GYRO NAVIGATOR INERTIAL NAVIGATION SYSTEM, AN/WSN-7(V)1, -7(V)2, -7(V)3

The AN/WSN-7(V) Ring Laser Gyro Navigator (RLGN) (Figure 4-50) is part of the AN/WSN-7(V) INS. Each RLGN is a self-contained unit that employs an Inertial Measuring Unit (IMU) using three single-axis Ring Laser Gyros (RLGs) and three accelerometers as the inertial reference to determine ship's position, velocity, heading, roll and pitch. The system continuously accepts ship's speed information from a speed log and/or Global Positioning System (GPS), and periodically accepts ship's position information from an external navigation reference (GPS), manually via a keypad and display on the RLGN control panels, or from the IP-1747/WSN Control Display Unit (CDU).

AN/WSN-7B(V) RING LASER GYROCOMPASS (RLG) INERTIAL NAVIGATION SYSTEM

The AN/WSN-7B(V) (Figure 4-41) is a self-contained system whose Inertial Measuring Unit (IMU) employs three RLGs and three accelerometers, in strapdown configuration. Unlike a stabilized gimballed system, high speed digital processing is employed to determine the ship's attitude (pitch, roll, and heading). The AN/WSN-7B(V) requires external ship's speed input and periodic input of position data. It uses ship's log speed to provide damping of vertical gyro loops. Position data from the Global Positioning System (GPS) is used to calibrate gyro drifts and to provide position resets to the inertial navigation function. The inertial sensor, speed, and position reset data are processed to generate continuous, accurate position and velocity data, in addition to heading, roll, and pitch reference.

Units and Assemblies

The AN/WSN-7B(V) cabinet is a single unit which is bolted directly to the ship's deck in a sheltered naval environment (i.e., not on the weather deck). The cabinet can be oriented in azimuth to any multiple of 90 degrees relative to the ship's keel. The AN/WSN-7B(V) must be optically aligned at installation using an alignment fixture which is temporarily mounted to Indexer Assembly mounting surfaces inside the unit. Alignment is then obtained by measuring offsets between the Alignment Fixture and the ship's reference lines. The AN/WSN-7B(V) includes the following functional elements: • Display/Control Panel • IMU • Mechanical Indexer Assembly • IMU/Shock Isolation System (SIS) Assembly • Card Rack Backplane Assembly containing the following CCAs: o Digital Processing and Sensor I/O Function Circuit Cards (3) o Indexer Control Electronics Circuit Card (1) o 4-Channel RS-422 Serial Data Interface Card (1) o Digital-to-Synchro/Synchro-to-Digital (D-S/S-D) Converter Circuit Cards (2) o Optional Interface Cards (up to 4) • Battery-Backed Power and Power Fault Detection System consisting of the following assemblies: o Electro-Magnetic Interference (EMI)/Radio Frequency Interference (RFI) Filter (1) o 25 VAC/DC, DC/DC Power Supply (Transformer Rectifier) (1) o Battery (1) o DC/AC Inverter Power Supply (1) o Vital Bus(fault detector) Printed Wiring Assembly(1) o Low Voltage Power Supply (1) Status and Alarm Relays (3) and Status Fault Indicator lamp (1)

Display Control Subsystem (DCS)

The DCS takes the Position, Velocity, and Time (PVT) information from the RTS and then creates the electronic navigation chart to places the PVT in a context that helps the user to navigate the ship. The DCS also acts as an interface to aid in a variety of navigation tasks such as piloting, voyage-planning, voyage-management, and training.

Maintenance Concept

The AN/WSN-7B(V) is designed for ease of maintenance through a modular design. Lowest Replaceable Units (LRUs) include the IMU, circuit cards, power supply, fuses, relays, and switches. All circuit cards and the power supply are connectorized for easy replacement. Replacement of relays and switches can be accomplished using standard screwdrivers and wrenches; no soldering or de-soldering is required. The IMU is positioned by precision alignment surfaces. IMU alignment offset parameters are maintained in a Programmable Read-Only Memory (PROM) on the Inertial Electronics (IE) card in the IMU.

Normal Operation

The AN/WSN-7B(V) is designed to operate automatically after application of power and requires minimum operator intervention during normal operation. A six-line, 40-character display and 28-key keypad provide display and operating controls for selection of a wide range of functions. These functions can be accessed for monitoring and modifying operating parameters, for evaluating system performance, and for selecting test and calibration modes.

SELECTING THE ALIGN MODE.

The AN/WSN-7B(V) will settle and operate as a gyrocompass (with degraded heading accuracy) without a source for either position or speed input and will operate as a full accuracy gyrocompass with only ship's speed applied. Position and velocity reference must both be provided for precise attitude alignment and navigation performance. At start-up, the system will automatically select a configured position and velocity reference based on priority. The operator can select from any configured position or velocity reference following power-up.

SOUND-POWERED TELEPHONE SYSTEM AN/WTC-2(V)

The AN/WTC-2(V) sound-powered telephone system is installed on some naval ships. This system replaces the existing EM and MJ call and signal circuits. The system is designed for interior shipboard use and, along with the sound-powered telephone circuits discussed earlier, provides two-way voice communication between shipboard terminal stations. You can signal and talk on the same cable. The system uses a variable number of 8 separate major units and may contain up to 144 terminal stations.

Net Access

The AN/WTC-2(V) system is an integrated point-to-point and net communications system. When the system is installed aboard ship, certain interconnecting wire pairs and their associated station numbers are reserved for net (string circuits) use. A net consists of designated stations and their associated units, and only the stations in a net have access to that particular net. The system contains several nets so certain stations may operate as a string circuit during particular conditions, such as general quarters. Ringing is not possible in a net; stations must already be manned to accomplish the desired communications.

Auto Cal Mode

The AUTO CAL mode is used at latitudes below 85° north or south. The AUTO CAL mode is used at initial start-up and should be implemented at least every 90 days during continuous operation to ensure accuracy of outputs. Automatic calibration requires 24 hours to complete but will continue as long as the mode switch is in this position.

Built-in Test Equipment

The BITE provides four types of built-in tests. These are hard-wired, software, software-initiated, and software-monitored built-in tests. The hard-wired BITE consists of test logic that is wired directly to the fault circuits. Fault signals that start the automatic shutdown sequence are hard wired. The software built-in tests are tests that are controlled by the processor, rather than by hard-wired logic circuits. The software-initiated BITE consists of hard-wired logic circuits that are activated by the processor. The software-monitored BITE circuits are not wired directly to fault circuits. Instead, the monitored parameters are compared to predetermined parameters known to the software. If the monitored parameters are determined to be wrong, the appropriate fault indicator is energized; and if the fault warrants, the gyro is shut down. When any fault is detected by the BITE, the ALARM indicator on the control indicator and the appropriate fault indicator are energized.

System Hardware

The Block 3 RTS computing platform is based on a 20-slot Versa-Modular Europa (VME) chassis. The VME chassis hosts a variety of interface cards and a single board computer or CPU (in slot 0) that is either a Motorola 68000 series processor or a Power PC processor. Some of the significant features of the Block 3 system include the following:

4.12.0 AN/SSN-6(V)2 NAVIGATION SENSOR SYSTEM INTERFACE SYSTEM

The Block 3 system is configured as a dual RTS. The current Block 3, Build 2 systems are all dual RTS systems. Figure 4-61 shows a typical NAVSSI system with dual RTSs. A Local Area Network (LAN) links these hardware components via fiber-optic cabling.

System Hardware

The Block 3, DCS computing platform is based on a TAC-4 computer with a trackball and keyboard. The TAC-4 workstation is a Hewlett Packard computer with a Series 9000-J210 processor providing open system architecture.X`

4.12.0 AN/SSN-6(V)2 NAVIGATION SENSOR SYSTEM INTERFACE SYSTEM

The DCS enables the operator to display the ownship's navigation sensor information, control the RTS(s), and display from the Global Positioning System (GPS). GPS data is initially received at the GPS Antenna, then is sent to the Global Positioning System (Versa Module Europa) Receiver Card (GVRC) that is installed in the Versa Modular Europa (VME) chassis of the RTSs. The GPS receiver cards (GVRC) together with the Digital Nautical Charts (DNC) database (supplied via CD-ROM) provide the information that may be displayed on the DCS and BWS monitors. For dual RTS systems, the RTSs exchange data via a reflective memory link. This feature allows the RTSs to share all incoming and outgoing data, thereby improving overall system robustness. In dual RTS configurations, the DCS communicates with each RTS via a Local Area Network (LAN). The BWS provides remote workstation access to the DCS.

Display Control Subsystem (DCS)

The DCS is mounted in a ruggedized, 19-inch rack with shock isolation intended to minimize the effects of battle damage. It is powered by an Uninterruptible Power Supply (UPS) that provides backup power if primary power fluctuates or there are power interruptions. This feature provides the time needed to perform an orderly system shutdown if there was shipboard power failure.

DFGMC Operation

The DFGMC is an "output only" type system and does not require any operator input for normal operation. When power is applied, the system automatically enters the Compass Heading mode. The Digital Display shows the present compass heading relative to magnetic north using the last calibration data stored by the system.

Calibration

The DFGMC is calibrated at the factory during assembly. However, every vessel has its own magnetic characteristics, which require that the DFGMC be compensated after installation. In addition, auto-compensation should be done whenever the Processor Unit is replaced, if it is moved to a new location on the vessel, or whenever the vessel goes to an area where the magnetic environment differs. The MV103DG system also has the capability of maintaining correct compensation regardless of the status of the ships Degaussing System.

DG Mode

The DG mode is used at latitudes above 85° north or south. When the gyrocompass is operating in the DG mode, the stable element is dampened by velocity signals and allowed to wander in azimuth. Earth rate correction is made by torquing the stable element in azimuth. The alpha angle is held constant and grid heading, rather than true heading, is sent to the ship's equipment. Otherwise, the equipment's function is the same as for the AUTO CAL mode.

Electronic Control Assembly

The Electronic Control Assembly is a watertight, deck-mounted unit which houses the control panel, power supply, servo amplifier, latitude compensation circuit, and alarm circuit. The servo amplifier printed circuit board and the power supply section (except for the power amplifier transistors) are easily removable for maintenance. The power amplifier transistors are attached to the cabinet frame for adequate heat dissipation. The Master Unit and Electronic Control Assembly will operate directly from an external 24-volt d-c power source or from the Power Converter described below. The Electronic Control Assembly may be mounted directly under the Master Unit or remotely, although the assembly should not be separated from the Master Unit by more than an arm's length to permit ease of operation during starting or adjustment of dial illumination. This will be discussed in further detail later in the chapter.

FAULT INDICATORS

The FAULT AIR indicator is energized when an over-temperature condition occurs in the power supply section of the control power supply, synchro signal amplifier, or the IMU. When this condition exists, an over-temperature no-go signal is sent to the control monitor, which starts the automatic power shutdown sequence.

Sound-Powered Headset-Chestsets

The H-200/U can also be modified to meet security requirements for use in the ship's communication center. The headset-chestset cord must contain not less than two conductors in a single shield.

Sound-Powered Headset-Chestsets

The H-201/U is designed for use by plotters and console operators. This set features a transmitter suspended from the headband on an adjustable boom. The normally open, spring-loaded, press-to-talk switch, S1, is in a junction box clipped to the talker's belt.

Sound-Powered Headset-Chestsets

The H-202/U is a specially designed set for use in high noise level areas. The receiver units are housed in noise-attenuating shells consisting of plastic caps lined with sound-absorbing material.

IC AND ACTION CUT-OUT (ACO) SWITCHBOARDS

The IC switchboard is the nerve center of the interior communications system. To obtain maximum protection, most IC switchboards are installed below the waterline and are energized from a normal, an alternate, and an emergency power supply to ensure continuous service. Since, in effect, all means of controlling the navigational systems on most ships depend upon proper functioning of the IC switchboards; their reliability is of the utmost importance. Many of the weapons and fire control (FC) circuits also receive their power from the IC switchboards; however, these systems are not part of the IC Electrician's responsibility.

IC/D Noninterrupted Call Signal Station

The IC/D noninterrupted call signal station is made of cast aluminum, with all of the equipment mounted on the cover except for the terminal board and a sound-powered jack outlet. Equipment mounted on the cover include a 16-position rotary selector switch, an index plate, a hand-operated magneto generator, a howler unit, and an attenuator. The associated sound-powered telephone circuit may be either the string or the switchboard type.

INERTIAL MEASURING UNIT

The IMU (fig. 4-38) is installed in a special precision IMU alignment rack located in the bottom of the electrical equipment cabinet, behind an access cover. Access to the IMU is gained by removing the access cover. The IMU contains the gimbal assembly, the electronics necessary to maintain the gimbal assembly, and associated electronics necessary to interface with the control, computing, and processing functions of the control power supply. The IMU also contains BITE circuitry and indicators and houses temperature controlling electronics.

TYPE JA

The JA switch (fig. 2-10) was developed primarily for circuit selection in sound-powered telephone applications. It provides a greater number of selections and is a smaller switch than the JR switch. The JA switch is furnished only with common rotor sections. Sixteen-position and 30-position JA switches permit selection of 16 and 30 circuits, respectively. With the JR switch, the maximum number of possible selections is seven.

TYPE JA

The JA switch also provides lower contact resistance by using either silver or silver-overlay contacts. With brass or copper, an insulating film forms over the contacts, which is only broken down if appreciable voltage and power are available in the circuit. However, in sound-powered telephone circuits, there is insufficient power to break down the film and relatively high resistance results. The silver-to-silver contacts of the JA switch consist of pure silver welded to beryllium copper. Silver or silver-coated contacts are now being used for the latest type JA switches and other low-current switches. In larger switches, silver (unless alloyed with other metals) is unsatisfactory because it vaporizes too readily due to arcing.

TYPE JA

The JA switch is available in two, six, and ten sections. An example of the switch designation is JA6C(16) for a 6-section, 16-position switch; here the first number designates the number of sections, the C indicates common rotor, and the number in parentheses indicates the number of positions.

TYPE JF

The JF switch (fig. 2-11) was developed primarily to replace toggle switches in the 10- and 20-switch boxes for sound-powered telephone applications.

TYPE JF

The JF switch is satisfactory for 120-volt ac applications up to 1 ampere. It is being used in sound-powered telephones, loudspeakers, microphone stations, and similar low-current equipment.

TYPE JF

The JF switch replacement uses silver-to-silver contact surfaces and provides a strong wiping action in moving between positions. Open circuit problems have been eliminated in this manner. The blade arrangement provides for a circuit between two adjacent contacts, such as in the 2JR switch previously discussed. The type 2JF has two such blade arrangements per switch deck. The standard switches have one, three, and five switching decks, which are indicated in the type designation by the number following JF.

TYPE JL

The JL switch is identical to the JR, except in size, mounting facility, and electrical rating. The diameter of the JL deck is approximately 1 ¾ inches, whereas the diameter of the JR deck is approximately 2 1/4 inches. The rating of the JL switch is 120 volts, 60 Hz, 5 amperes. Standard types are available in three, five, and ten sections. The JL switch has a threaded bushing for single-hole mounting.

TYPE JR

The JR switch has a stop deck, which permits setting the switch to the number of positions desired. Pins or screws inserted in the stop deck immediately after the desired last position will limit the switch movement to the positions between these points.

TYPE JR

The JR switch is stocked in multiples of five sections (up to 25 sections). In some cases, a switch with a number of sections (not a multiple of five) has been installed. If this switch must be replaced, a switch with the next largest number of sections that is a multiple of five should be installed, if space permits.

Master Unit

The Master Unit, shown in figure 4-27 contains the compass element. The two basic parts of the Master Unit are the binnacle and the base. The binnacle is shock-mounted in the base and the shock mounts are positioned to act through the center of gravity of the binnacle. The base is a casting which is fixed to the deck by four bolts with plus or minus 5 degrees of freedom in azimuth to permit accurate alignment with the ship.

MK 23 MOD 0 GYROCOMPASS SYSTEM

The Mk 23 Mod 0 gyrocompass system (fig. 4-22) consists of the master unit, control cabinet, speed unit, alarm control unit, a compass failure annunciator, and an alarm belt.

MK 23 MOD C-3 GYROCOMPASS SYSTEM

The Mk 23 Mod C-3 gyrocompass system is identical to the Mk 23 Mod 0 system with the exception that the Mk 23 Mod C-3 system uses solid-state devices in place of vacuum tubes in the control cabinet. In addition, two more units are used in the C-3 system. These two additional units arc

Nav Mode

The NAV mode is the normal mode of operation and is used between latitudes 85° north or south. If the NAV mode is initially selected as the mode of operation, the alignment sequence must be completed before the gyrocompass is capable of providing full accuracy outputs. This sequence takes approximately 4 hours. The alignment sequence is completed when the MODE ALIGN indicator goes off and the MODE NAV indicator comes on.

Nav Mode

The NAV mode, the primary operating mode, is mechanized the same as the AUTO CAL mode. In the NAV mode, the heading is not slewed and the alpha angle is held at zero; thus, the equipment becomes a north-pointing gyrocompass.

System Software

The NAVSSI AN/SSN-6 Block 3 system software uses two Computer Software Configuration Items (CSCls): the DCS CSCI and the RTS CSCI.

System Capabilities and Interfaces

The NAVSSI Block 3 hardware and software marks an improvement over previous versions in several areas: • It expands the number of sensor and user systems supported. • It incorporates a Global Positioning System (GPS) receiver capability directly into the NAVSSI system. • It has refined algorithms that are used to calculate an integrated navigational solution. • It further expands the navigation tools available to the ship's navigation team.

OPTICAL LOSS TEST SET - ANRITSU

The Optical Loss Test Set is an invaluable asset to the Fiber Optics Technician. You will learn the importance of accurate references and the standard procedures for obtaining and comparing them.

Records

The PMS of the 3-M Systems has cut the records and inspections of the gyrocompass to a minimum. Naval Ships' Technical Manual, chapter 252, no longer requires lengthy records to be kept on gyrocompass equipment; however, it specifically requires the record book that is sent with each compass to be scrupulously maintained.

BUS FAILURE ALARM UNIT

The POWER ON light, a back-lighted push button, tests the audible signal of the unit. The SILENCE RESET push button silences the alarm (the red flag will not reset until power is restored to the bus) and resets the unit when power is restored to the bus.

Power Converter

The Power Converter is used for applications where the gyrocompass equipment must operate from a single phase 115-volt, a-c, 60 or 400 cps power source. The converter is housed in a watertight enclosure and its purpose is to convert a-c input power to 24-volt d-c for operation of the compass equipment. This will be discussed in further detail later in the chapter.

Adjusting Display Response Damping - MV103AC

The RESPONSE toggle switch (Fig. 4-18) selects any of three fixed values of display damping. The function of display damping is to average a number of headings over time to present a stable display to the operator. This function has no effect on the response time of the (1A3) Sensor / Processor electronics. When a damping time is selected, the LCD shows "d-1" (FAST position), "d-2" (MED position), or "d-3" (SLOW position) for two seconds. Selection of the response damping value is largely a matter of operator preference and the vessel's operating condition. For example, when operating in rough seas or at high speeds where heading is apt to change rapidly, the operator may select SLOW which causes the display data to be averaged over a 17- second period. The heading continues to update at one-second intervals, but the display is the average of the most recent 17 seconds. Conversely, when operating in calm seas or slow speeds where heading changes slowly, the operator may select FAST, which causes the display data to be averaged over a 3- second period. MED averages the heading data at a 9-second interval. Response damping time may be selected at any time in the Compass Heading or Set Course operating modes. RESPONSE has no effect in the GPS mode.

Adjusting Display Response Damping - MV103ACS and MV103DG

The RESPONSE toggle switch selects any of two fixed values of display damping. The function of display damping is to average a number of headings over time to present a stable display to the operator. This function has no effect on the response time of the (1A3) Sensor / Processor electronics. Selection of the response damping value is largely a matter of operator preference and the vessel's operating condition. For example, when operating in rough seas or at high speeds, where heading is apt to change rapidly, the operator may select SLOW, which causes the display data to be averaged over a 9- second period. The heading continues to update at one-second intervals, but the display is the average of the most recent 9 seconds. Conversely, when operating in calm seas or slow speeds, where heading changes slowly, the operator may select NORMAL, which causes the display data to be averaged over a 3- second period. Response damping time may be selected at any time in the Compass Heading mode.

Normal Operation

The RLGN is designed to operate automatically after application of power and acceptance of the first position reset and requires minimum operator intervention during normal operation. A 6-line, 40-character display and 28-key keypad provide display and operating controls for selection of a wide range of functions. These functions can be accessed for monitoring and modifying operating parameters, for evaluating system performance, and for selecting test and calibration modes.

RAID

The Random Access, Integrated Drive (RAID) is a mass storage device that uses an array of up to eight half-height drives each having a capacity of up to 18.0 gigabytes. The RAID has a maximum storage capacity of up to 144 gigabytes. These integrated drives provide mass storage for navigational charts for NAVSSI system. Information can be read-from or stored-to the RAID drive like any other hard disk drive.

SPERRY MK 23 GYROCOMPASS SYSTEMS

The Sperry Mk 23 gyrocompass is a small electrical compass that is used aboard many naval vessels to furnish heading data. On many of the small combatant vessels and larger auxiliary vessels, it is used as the master compass. On some of the larger combatant vessels, it is used as a backup compass. The compass is capable of indicating true north accurately in latitudes up to 75°N or S. The compass also can be used as a directional gyro when nearer the poles.

SPERRY MK 27 GYROCOMPASS SYSTEM

The Sperry Mk 27 gyrocompass is a rugged, low-voltage electrical compass used as the master compass on small craft and as the auxiliary compass on larger ships. The Mk 27 gyrocompass is designed to operate on 24-volt dc or 115-volt, 60- or 400-Hz, single-phase power.

Alarm Bell

The alarm bell is used with the annunciator to provide an audible indication of problems within the gyrocompass system.

Alarm Control Unit

The alarm control unit contains the necessary relays and components to actuate the lamp on the visual alarm indicator or the bell alarm when certain portions of the system become inoperative.

Precession

The rotor of a gyro has one plane of rotation as long as its axle is aligned with, or pointed at, one point in space. When the axle tilts, turns, or wobbles, the plane of rotation of the rotor changes. Plane of rotation means the direction that the axle is aligned or pointed.

Servo Amplifier

The amplifier is the heart of the gyrocompass follow-up system. From the block diagram of figure 4-33 it can be seen that the amplifier consists of three basic circuits: a single-needed input stage, a driver stage, and a power output stage. Additional stages of demodulation and modulation are used to accomplish feedback.

Circuit EM - Sound-Powered Telephone Signal Circuit

The associated sound-powered telephone circuit is independent of the signal circuit and provides the voice communication facilities between stations. Each sound-powered telephone circuit can accommodate only one conversation over its facilities. The IC/D call signal station (fig. 5-21, views A and B), normally called a growler or a howler, uses a magneto generator to transmit a non-interrupted or interrupted signal to a selected station.

AUDIO AMPLIFIER

The audio amplifier (fig. 5-16) consists of a low-level, three-transistor amplifier (Q1 through Q3) and a power amplifier (Q4 and Q5), with negative feedback employed throughout. The output transformer (T3, not shown) has two secondaries: the first is used with the loudspeakers and the latter, a tapped winding, is used for as many as six sound-powered telephone outlets. The amplifier provides a 10-watt output.

BACKUP POWER

The backup power supply consists of the inverter and the inverter module, located in the synchro signal amplifier, for backup during loss of single-phase power, and the battery set and relays located on the transformer-rectifier assembly, for backup during loss of 3-phase power.

Equipment Description

The basic DFGMC System consists of the (1A3) Sensor / Processor Unit, (1A2) Junction Box, (1A1) Main Display, (PS1) Uninterruptible Power Supply, plus associated power and signal cabling. System specific equipment may include the (1A6) Degaussing Interface Unit, (1A4) RS232/422 Display Driver, and (1A5) RS232/422 Remote Displays. All system components are shown in figure 4-15.

RELAYS

The basic difference between ac and dc relays lies in the armature and magnet core construction. The armature and magnet cores of an ac relay are made up of laminations, and those of a dc relay are of solid material. The use of laminations in an ac relay reduces the heating due to eddy currents. In addition, a copper strap or ring (called a shorted turn) is placed near the end of the pole piece of an ac relay to reduce chatter during operation.

External Data Interfaces

The basic digital data interface to the AN/WSN-7B(V) includes an RS-422 Input/Output (I/O) channel which provides interface for Doppler Sonar Velocity Log (DSVL) digital speed input, an RS-422 interface for an external (optional) Remote Control Display Unit (RCDU), and one spare RS-422 interface which can be configured for specific serial data requirements. Table 4-5 lists the functions and characteristics of the three standard serial digital data interfaces.

External Data Interfaces

The basic external data interface also consists of a 1-pulse per second timing interface, which provides time synchronization in a dual-system configuration; an RS-422 serial data interface, which exchanges position, velocity, and status information in a dual-system configuration; an RS-422 interface to an external CDU; and an ATM interface to External Local Area Network (LAN). Heading, roll, pitch, north-south velocity, east-west velocity and total velocity are output as analog (synchro) data. Synchro amplifiers are provided for the heading, roll and pitch outputs. Table 4-15 outlines the serial interface and data message characteristics. Table 4-16 lists the synchro output characteristics and defines the synchro reference requirements.

External Data Interfaces

The basic external data interface to each RLGN consists of Naval Tactical Data System (NTDS) Standard Type A parallel slow, NTDS Standard Type D high level serial, and Type E low level serial interfaces. These interfaces are Circuit Card Assemblies (CCAs) located in the Input/Output (I/O) Card Rack Assembly. The combat systems suite or aircraft alignment aboard the ship on which the RLGN system is installed determines the specific configuration of NTDS interface circuit cards.

FUSES AND FUSE HOLDERS

The basic type of fuse used in the IC switchboard is designated F03 plastic or ceramic with silver-plated ferrules. The fuse holders used in IC switchboards are the dead-front blown fuse indicating type. The two basic types of fuse holders used with the F03 fuses are the FHL10U and the FHL11U.

NORMAL POWER

The battery charger receives high- and low-voltage sensing signals and a temperature-sensing signal from the battery set. The battery charger uses the temperature-sensing signal to regulate the 35 volts dc to provide a charging voltage to the battery set. The charging voltage is present as long as the 3-phase, 115-volt ac ship's power is available and turned on.

Binnacle

The binnacle contains the compass element and is completely filled with flotation fluid. In addition to the sensitive element, it contains a bellows located inside the bottom cover, which accommodates the contraction and expansion of the fluid with temperature changes. Also on the binnacle are the card viewing window, the cager diaphragm, the binnacle electrical connector, and the evacuating and filling nozzles

Phone/Distance and Station-to-Station Lines

The bridge-to-bridge phone/distance line is used between the delivery and receiving ships for ship-to-ship coordination during replenishment-at-sea operations. The line is made up and kept by the ship's deck division. Distance markers are attached to the line at 20-foot intervals.

Maintenance of Relays

The buildup of film on the contact surfaces of a relay is another cause of relay trouble. Carbon buildup, which is caused by the burning of a grease film or other substance (during arcing), also can be troublesome. Carbon forms rings on the contact surfaces; and as the carbon rings build up, the relay contacts are held open.

Electrical Equipment Cabinet

The cabinet contains a wiring harness, alarm relays, power relays, electromagnetic interference (EMI) filters, an elapsed time meter, capacitor assemblies, and a blower for IMU cooling, and the IMU rack. A connector panel located on the rear of the cabinet provides the electrical cable interconnections for cabling to external equipment, including primary power.

Call Hold

The call hold function is used by a terminal station that has originated a call and desires to maintain communication with the called station while answering an incoming call. To perform the call hold function, you should use the following procedure: 1. Inform the called station that you have an incoming call, and tell the called station to stay on the line while you answer the call. 2. Answer the call according to normal procedures by setting the PLACE CALL/ANSWER switch to the ANSWER position. 3. When you have finished with the incoming call, set the PLACE CALL/ANSWER switch to the PLACE CALL position and continue with your original call.

IC/D Noninterrupted Call Signal Station

The call signal stations located in noisy spaces may include a visual indicator lamp to alert personnel of an incoming call. A relay box nippled to an indicator lamp is installed adjacent to each call signal station. The relay coil is connected to the howler circuit of the station. The relay contacts are connected to the nearest emergency lighting circuit. When the station howler is activated, the relay coil is energized and the relay contacts operate to complete the circuit from the lighting system to energize the indicator lamp.

Mechanical Switches

The cam-action mechanism uses a rotary motion of the shaft to move cams, which in turn operate sensitive switches. The points of operation of the sensitive switches are varied by adjusting the angular positions of the cams with respect to the shaft on which they are mounted. Mechanical switches are used with the following systems: QA Air-lock indicator PW Clutch-position indicator SP Shaft-position alarm LS Submersible steering-gear alarm DW Wrong-direction alarm TR Hull-opening indicator VS Valve-position indicator

Central Control Station Local IC Switchboard

The central control station switchboard receives its normal power supply (120-volt, 60-Hz, 3-phase) from one of the ship's power panels. One of the ship's lighting panels provides the emergency supply. The switchboard also includes an ABT device, power available indicator lights, and supply switches for the various machinery control systems.

Action Cut-out (ACO) Section

The switches found on these panels are for the repeater and control circuits of the gyrocompass, wind indicating, propeller revolution, propeller order, engine order, and underwater log systems.

Clapper Relay

The clapper relay (fig. 2-21) has multiple sets of contacts. As the circuit is energized, the clapper is pulled to the magnetic coil. Pulling the arm of the clapper forces the movable contact upward to move the pushrod and the upper movable contact. This action could be repeated for as many sets of contacts as required. Thus, it is possible to control many different circuits simultaneously. To the maintenance person, this type of relay can be a source of trouble. The motion of the clapper arm does not necessarily assure the tandem movement of all the movable contacts. If the pushrod was broken, the clapper arm would push the lower movable contact upward but would not move the upper moveable contact, thereby not completing the circuit.

RELAYS

The coil design is influenced by the manner in which the relay is used. When the relay is designed for series connection, the coil is usually wound with a fairly small number of turns of large wire because the load current will be flowing through the winding. When the relay is designed for shunt connection, the coil is wound with a large number of turns of small wire, which will increase the resistance and thus lower the current through the coil.

Compass Failure Annunciator

The compass failure annunciator is a visual alarm indicator. It provides a visual indication of problems within the gyrocompass system. Under normal conditions, the lamp on the indicator is lighted continuously. When a failure occurs within the system, the lamp flashes or goes out. A test push button is provided on the annunciator. In some installations a type B-51 or B-52 alarm panel is used in place of the annunciator.

Design Features

The compass is compensated for the effects of varying latitude. In addition, a servo follow-up system is provided in the azimuth axis to keep the phantom yoke support aligned with the gyrosphere as the vessel turns; it also drives the compass card and any data transmission system that may be included. Provision is made so that the gyrocompass may be equipped with a step transmitter, a I-speed synchro transmitter, a 36-speed synchro transmitter, or any combination of these units. Either 60 or 400 cps heading data synchros can be supplied. The compass card is visible for direct reading, and has the normal sense of relative rotation for direct steering purposes. A built-in alarm is utilized to give a direct indication of failure in power supply or follow-up amplifier. Because of the low viscosity of the suspension and ballistic fluids, no heaters are required in the Mark 27 Gyrocompass.

Control Cabinet

The control cabinet contains all the equipment required for operating and indicating the condition of the master compass except the visual alarm indicator and the alarm bell. The control cabinet houses the control panel, control amplifier, follow-up amplifier, and power supply.

Control Indicator

The control indicator (fig. 4-35) is a hinged assembly located in the top of the electrical equipment cabinet. It is secured to the cabinet with quick-release fasteners. The control indicator contains all the operator controls and indicators for the gyrocompass set. The control indicator also contains built-in test equipment (BITE) for the major assemblies and subassemblies. BITE circuits identify equipment faults and provide visual indications of the faulty assembly or subassembly.

PANEL LIGHTING

The control indicator panel lighting is controlled by a potentiometer marked PANEL. The PANEL potentiometer is excited by ±15 volts dc. The potentiometer adjusts a biasing level applied to the illumination sensing circuit in the dimming control circuit card. The output of the sensing circuit drives the dimming control amplifier. The output of the dimming control amplifier is an aboveground variable voltage determined by the position of the PANEL potentiometer. Figure 4-39 identifies the lights controlled by the PANEL potentiometer.

STATUS INDICATOR AND DISPLAY LIGHTING

The control indicator's status indicators and the digital display are controlled by the DISPLAY potentiometer. The potentiometer provides a triggering level input (0 volts to +5 volts) to a controlled-width blanking pulse circuit, located on the dimming control circuit card. The blanking pulse is applied to the indicator enabling logic, also on the dimming control circuit card. When the input to any indicator, controlled by the DISPLAY potentiometer, is determined to be correct by the display logic, the indicator is energized.

FAULT INDICATORS

The control monitor also senses the voltage and frequency of the 3-phase, 115-volt ac power and synchro reference inputs at the transformer rectifier. If the 3-phase input is lost or exceeds tolerances, the control monitor will switch the gyro to battery operation and send a signal to the control indicator, causing the BATTERY OPR indicator to come on. If the single-phase input is lost or exceeds tolerances, the control monitor will disconnect the ship's faulty input switch on the inverter, sending a signal to the control indicator, causing the ALARM indicator to set.

CONTROL POWER SUPPLY

The control power supply (fig. 4-36) contains the control, computing, processing, analog/digital conversion, input/output interface, and power supply electronics for the gyrocompass set. The control power supply also contains capacitor assemblies, cooling blowers, BITE, and the battery charging electronics for charging the battery set.

SYNCHRO SIGNAL AMPLIFIER

The synchro signal amplifier (fig. 4-37) is installed in the electrical equipment cabinet. It is held in the cabinet by quick-release fasteners. The synchro signal amplifier contains four synchro buffer amplifiers, an inverter power supply, cooling blower, and BITE.

Fiber Coating

The core and cladding are encased in a coating, which are usually one or more layers of polymer or acrylate material. In cables used for inside installations, the fiber is coated with a tight buffer, which may include two layers of acrylate material. Fibers with tight buffer coatings are generally used for patch cords and similar applications indoors. Tight buffer diameters are typically 900 microns.

Fiber Core

The core is the optical transmission path. The light has to remain in the core and travel through the fiber to the receiving end. It is important to realize that the core is made from a solid section of ultrapure, ultratransparent silicon dioxide or fused quartz (glass). If seawater were as clear as a fiber, you could see to the bottom of the deepest ocean trench, the 32,177-foot-deep Mariana Trench in the Pacific.

TYPE JR

The designations of JR switches are determined by the type of section (rotary and stationary contacts) followed by the number of sections in the switch. For example, a 2JR10 switch denotes a JR switch with ten 2JR sections.

Auto Cal Mode

The digital display indicator provides for local display of the quantities shown in table 4-2. Data for display is selected by the DSPL SEL switch.

APPARENT ROTATION OF THE GYROSCOPE

The effect of the earth's rotation causes the north end of the gyroscope axle to rise when east of the meridian and to fall when west of the meridian in any latitude. This tilling effect provides the means by which the gyroscope can be made into a north-seeking instrument.

Electrical Equipment Cabinet

The electrical equipment cabinet (fig. 4-34) provides the mechanical and electrical interface for the five major assemblies. The cabinet also provides forced air cooling for the IMU.

Electronic Control Assembly

The electronic control assembly shown in figure 4-31, houses the operating controls, follow-up servo amplifier, alarm circuitry, power supply, latitude control circuitry, and gyrocompass control functions. It can be mounted directly under the gyrocompass to form a compact arrangement or conveniently nearby for easy access to both units. All internal components are easily accessible by removal of the chassis and panel combination through the front.

EMERGENCY POWER DISTRIBUTION SYSTEM

The emergency power distribution system is 450 volts, 3 phase, 60 Hz with transformer banks at the emergency distribution switchboards to provide 120-volt, 3-phase power for the emergency lighting system.

EMERGENCY POWER DISTRIBUTION SYSTEM

The emergency power distribution system supplies a limited amount of power for ship control and for the operation of vital equipment when the ship's service distribution system fails. An emergency power distribution system is installed on most combatant ships and some auxiliary ships.

EMERGENCY POWER DISTRIBUTION SYSTEM

The emergency switchboard is connected by feeders (fig. 3-3) to at least one and usually to two different ship's service switchboards. One of these ship's service switchboards is the preferred (normal) source of ship's service power for the emergency switchboard, and the other is the alternate source. The emergency switchboard and the distribution system are normally energized from the normal source of ship's service power. If this source of power should fail, bus transfer equipment automatically transfers the emergency switchboard to the alternate source of the ship's service power. If both the normal and alternate sources of power fail, the emergency generator will start automatically within 10 seconds and the emergency switchboard will automatically transfer to the emergency generator.

Engine-room Local IC Switchboard

The engine-room switchboard operates on 120-volt, 60-Hz, single- or 3-phase ac power, There are two sources of power available: normal and emergency. The nearest main IC switchboard provides the normal power supply, The emergency power supply comes from a local emergency lighting circuit. The emergency power supply provides the switchboard with power if the normal supply is lost. The engine-room switchboard includes supply switches, an ABT device, and power available indicator lights.

Latitude Set

The entry of latitude data maybe made during the leveling sequence (except during the north and south gyrocompassing phases) and at anytime the system is NAV ready. The gyrocompass is ready to receive a latitude entry when the ENTER LAT switch indicator (Fig. 4-35) is on. The software program commands the ENTER LAT switch indicator on when power is applied and when the position of the MODE switch is changed. If the ENTER LAT switch-indicator is not on, entry can be accomplished by pressing the ENTER LAT switch indicator ONCE. The gyro compass will then be able to receive a latitude entry for 1 minute.

UNIT 6

The extension visual signal device (fig. 5-29) provides a visual signal to a location remote from a terminal station when additional signaling is required due to high noise levels or physical barriers to sound near a station. The extension visual signal device uses a 50-watt incandescent lamp.

Fuse Holders

The extensive use of low-voltage power supplies has required the use of incandescent lamps in place of neon glow lamps in some indicator light circuits. A modification of the FHL10U fuse holder provides a third terminal connected to a 28-volt incandescent lamp in the cap. By insertion of a suitable resistor between the load terminal and the added terminal, the lamp will be energized by a sufficient voltage to become visible when the fuse has blown. In some low-voltage fuse holders the resistor and lamp are included within the clear plastic cap. Low-voltage fuse holders should not be used in sensitive, low-current equipment. Where an overload condition occurs and the fuse blows, the low-resistance indicator circuit may pass sufficient current to damage the equipment.

Built-in Test Equipment

The fault indicators are located on the control indicator. They are labeled FAULT AIR, FAULT DI, FAULT CTR, FAULTPS, BATIERY STAT, BATTERY OPR, FAULT BFR, HDG FAIL, FAULT IMU, and ALARM. These indicators serve to lead the operator to the failed area of the system.

Fiber Cladding

The fiber manufacturer would express the core-to-cladding size relationship for a fiber with a 62.5 micron core and a 125 micron cladding as 62.5/125.

System Operation

The system can be used to make point-to-point (station-to-station) calls and conference calls. The system also provides net access, call holding, and executive override functions.

UNIT 1

Unit 1 (fig. 5-24) is a bulkhead-mounted terminal station consisting of three separate components: call-signal station A1, handset HS1, and handset holder MP1.

NORMAL POWER

The gyro is turned on and off by logic circuits in the control monitor, which is located in the control power supply.

Gyro Shaft Pillow Blocks

The gyro shaft is secured to the frame by two pillow blocks, as shown in figure 4-30. A pin, driven through a hole in one of the pillow blocks into a keyway in the end of the stator shaft, prevents rotation of the shaft. The pin does not go all the way through the shaft. After the gyro and pillow blocks are assembled in the frame, nuts are screwed on the threaded gyro shaft to position the shaft. These nuts hold the shaft stationary along the pillow block axis of the frame and provide a means of positioning the entire gyro and shaft to establish mechanical balance of the frame and motor assembly. The pillow blocks and holding screws are individually fitted to the frame and are not interchangeable.

Records

The gyrocompass service record book is used to record important repair information (major part replacement, overhaul, and field change installation), providing a continuous repair history of each gyrocompass. Instructions for maintaining the record book are given in the front of the book.

NORMAL POWER

The gyrocompass will automatically switch to battery operation when the 3-phase or single-phase ship's power input is lost, loses a phase, or exceeds prescribed voltage or frequency tolerances. If the single-phase input is lost or exceeds tolerances, the system will shift to inverter backup.

Design Features

The gyrosphere containing the gyroscope rotor is immersed in silicone fluid, and is designed and adjusted to have neutral buoyancy. The weight of the gyrosphere in the fluid is canceled by the buoyant force of the displaced fluid. This feature is a distinct advantage in that (1) the weight of the gyrosphere is removed from the sensitive-axis bearings, (2) the gyrosphere and bearings are protected from excessive shock loads, (3) sensitivity to shifts of the center of mass of the gyrosphere relative to the sensitive axis are eliminated providing improved accuracy, and (4) the effects of accelerations are minimized because the center of mass of the gyrosphere and the center of buoyancy are made coincident.

Gyrosphere

The gyrosphere, shown in figure 4-29, is the north seeking part of the gyrocompass. It derives its name from the fact that the gyro wheel is mounted within a spherical enclosure. The sphere is 6.5 inches in diameter; at running temperature, the specific gravity of the sphere is the same as that of the fluid in which it is immersed. Because the sphere is in neutral buoyancy, it exerts no load on the vertical bearings which, therefore, serve only as guides for the sphere. Flotation of the gyro in this manner not only reduces pivot friction, but serves to protect the gyro pivots from destructive shocks. The sphere has been evacuated and partially filled with helium gas. This gas serves to transfer the heat generated by the gyro motor windings to the surface of the sphere.

SIGNAL DEVELOPMENT

The heading sine and cosine signals from the resolver preamplifier are converted to true heading sine and cosine signals in the 1X and 36X true heading converters before being sent to the synchro signal amplifier and the analog/digital (A/D) multiplexer. The true heading sine and cosine data, like the roll and pitch data, are amplified, buffered, and converted to standard three-wire synchro data in the synchro signal amplifier. True heading data is subsequently sent out as S1, S2, and S3 synchro data.

Linear Switches and Switching Equipment

The heart of the Switchboard is the plug-in, modular linear movement switch. It replaces the rotary barrel switch. The linear switch is superior because of its distinct advantages: compact design, factory-wired and tested for immediate use, greater switching capability, and remote control. Also, the linear switch offers additional advantages such as lower cost, decreased maintenance, greater reliability and standardization for new construction and updating existing installations.

Compass Element

The heart of the compass is the compass element and it is shown in figure 4-28 as removed from the binnacle. It consists of the support plate, follow-up system components, compass card, phantom fork, vertical ring and gyrosphere.

SINGLE-METAL TYPE

The heat-sensitive element is a metal tube around the heater. The tube lengthens when heated and opens the overload relay contacts.

BIMETAL TYPE

The heat-sensitive element is a strip or coil of two different metals fused together along one side. When heated, one metal expands more than the other, causing the strip or coil to bend or deflect and open the overload relay contacts.

INDUCTION TYPE

The heat-sensitive element is usually a bimetal strip or coil. The heater consists of a coil in the motor circuit and a copper tube inside the coil. The copper tube acts as a short-circuited secondary of a transformer and is heated by the current induced in it. This type of overload relay is used only in ac controllers, whereas the previously described types of thermal overload relays may be used in ac or dc controllers. 2-51 UNCLASSIFIED

SWITCHING CIRCUIT

The incoming and outgoing voice signals are coupled through capacitor C1 of the amplifier. CR1 is in the circuit to protect Q6 from surges while it is in the cutoff state.

Servo Amplifier

The input stage provides amplification of the pickoff signal to control the push-pull driver stage. A driver is utilized for each half of the signal to provide sufficient voltage and power amplification for operation of the push-pull power amplifier stage. Stabilization of the follow-up system is derived from the feedback of a portion of the output signal. To provide rapid response, free from oscillation, this feedback voltage is demodulated and developed into a rate signal. The rate signal is then modulated and mixed with the pickoff signal to give the amplifier the required dynamic characteristics.

4.12.0 AN/SSN-6(V)2 NAVIGATION SENSOR SYSTEM INTERFACE SYSTEM

The inputs to the AN/SSN-6 are processed, and in the AUTO mode, NAVSSI selects the best source selection for each output component. In the manual mode, the source selection is made by the operator to provide the appropriate output.

LENGTH OF CABLE

The insulation resistance of a length of cable is the resultant of a number of small individual leakage paths or resistances between the conductor and the cable sheath. These leakage paths are distributed along the cable. Hence, the longer the cable, the greater the number of leakage paths and the lower the insulation resistance. For example, if one leakage path exists in each foot of cable, them will be 10 such paths for current to flow between the conductor and the sheath in 10 feet of cable, and the total amount of current flowing in all of them would be 10 times as great as that which would flow if the cable were only 1 foot long. Therefore, to establish a common unit of comparison, cable-insulation resistance should be expressed in megohms (or ohms) per foot of length. This is determined by multiplying the measured insulation resistance of the cable by its total length in feet.

Casualty Communications

The jackbox outlets in each four-gang jackbox are connected in parallel, and each box contains a nameplate that identifies the associated below-deck station and circuit identification X40J.

SOLENOIDS

The magnetic flux produced by the coil will result in establishing north and south poles in both the core and the plunger. These poles have such a relationship that the plunger is attracted along the lines of force to a position of equilibrium when the plunger is at the center of the coil. As shown in figure 2-27, the de-energized position of the plunger is partially out of the coil due to the action of the spring. When voltage is applied, the current through the coil produces a magnetic field that draws the plunger within the coil, thereby resulting in mechanical motion. When the coil is de-energized, the plunger returns to its normal position by the spring action. It is interesting to note that the effective strength of the magnetic field on the plunger varies with the distance between the two. For short distances, the strength of the field is strong; and as distances increase, the strength drops off quite rapidly.

Master Unit

The master unit consists of a shock-mounted, oil-filled binnacle and the gyrocompass element. The master unit is designed for deck mounting and weighs approximately 100 pounds. The compass element is the principle unit of the compass system and is gimballed in the binnacle to allow ±45° of freedom about the pitch and roll axes. Drain plugs are located in the lower bowl for draining the oil.

FIBER OPTICS

The most common use of fiber optics today is as a transmission link connecting two electronic devices or circuits. The fiber optic link changes electrical signals into optical signals, sends or transmits light signals through the fiber and then changes the optical signals back into electrical signals.

Linear Switches and Switching Equipment

The new Navy Switchboards serve key functions in their operating systems on board combatant vessels. They provide power, amplify signals and route data from various data collecting systems for navigation or fire control of missiles and guns. Where computers are involved, the Computer Switching Control Panel gives command the option of selecting computers and the routing of data to the peripheral equipment.

Push-Button Switches

The normal contact arrangement of a push-button switch is either make or break, as shown by the schematic symbols in figure 2-3, view A. View B of figure 2-3 is a picture of a push-button switch. The make type of switch is usually a start switch; the break type of switch is usually a stop switch. Either switch may be locking or non-locking. There is also a break-make push-button switch (not shown).

NORMAL POWER

The normal power supply consists of the control monitor, battery charger, 5-volt regulator, 13-volt regulator, DC/DC module, and transformer rectifier. These are all located in the control power supply. Three-phase, 115-volt ac ship's power is routed through an EMI filter and power circuit breaker to the transformer rectifier for normal power. The transformer rectifier converts the 115 volts ac to 35 volts dc and unregulated 28 volts dc. The 35 volts dc goes to the battery charger and the unregulated 28 volts dc is sent to the 5-volt and 13-volt regulators.

PANEL 1

The normal power supply is from the forward ship's service distribution switchboard. The alternate power supply comes from the after ship's service distribution switchboard. The emergency power supply comes from the forward emergency distribution switchboard. The bus may also be energized by a casualty power terminal installed on the board, which, in turn, receives its power via portable cable from a remotely located riser nearby.

LOCAL IC SWITCHBOARDS

The number of local IC switchboards installed on a ship depends on the type and class of that ship. As stated earlier, local IC switchboards provide local control of circuits vital to the operation of a space. The local IC switchboards that will be discussed in this chapter are (1) engine room, (2) central control station, and (3) steering gear room. There may be other local IC switchboards installed aboard ships, depending on individual ship requirements.

Spare Optical Fibers

The number of spare optical fibers shall be in accordance with the ship specification and system drawings. Spare fibers are provided in both trunk cables and local cables that penetrate bulkheads or decks.

Stuffing Tubes

The nylon stuffing tube is available in two parts. The body, O-ring, locknut, and cap comprise the tube; and the rubber grommet, two slip washers, and one bottom washer comprise the packing kit.

Stuffing Tubes

The nylon stuffing tube is lightweight, positive-sealing, and noncorrosive. It requires only minimum maintenance for the preservation of watertight integrity. The watertight seal between the entrance to the enclosure and nylon body of the stuffing tube is made with a neoprene O-ring, which is compressed by a nylon locknut. A grommet-type neoprene packing is compressed by a nylon cap to accomplish a watertight seal between the body of the tube and the cable. Two slip washers act as compression washers on the grommet as the nylon cap of the stuffing tube is tightened. Grommets of the same external size, but with different sized holes for the cable, are available.

TYPE JF

The original production of the switches had a detent to limit the switching action to two positions. The present design has a 12-position detent arrangement with adjustable stops. The stops can be adjusted by removing the four screws on the back plate and arranging the stop arms mounted on the switch shaft to give the number of positions desired.

STATUS INDICATOR AND DISPLAY LIGHTING

The period of the blanking pulse, established by the DISPLAY potentiometer, determines the illumination level. Indicators on the control indicator that are controlled by the DISPLAY potentiometer are shown in figure 4-40.

Fuse Holders

The types FHL10U, FHL11U, and FHL12U (fig. 2-30) consist of a fuse holder body and a fuse carrier. The body is mounted on the panel, and the carrier with the fuse placed in the clips is inserted into the body in a manner similar to inserting a bayonet-type lamp into a socket.

UNIT 2

Unit 2 (fig. 5-26) is similar to unit 1 except that the call-signal station has a front-crank hand ringing generator instead of a side-crank hand ringing generator

Distribution Boxes

The phosphor-bronze fuse clip and supplementary bent-wire fuse retainer have been superseded by a steel copper-clad silver-plated fuse clip. The steel fuse clips do not require fuse retainers to prevent dislodgement of fuses under shock and vibration. The wire fuse retainers impose a hazard of possible accidental dislodgement and falling into bus work to cause short circuits. To eliminate this hazard on both vital and nonvital circuits that require frequent removal of fuses, and where difficulties occur with loosening of existing phosphor-bronze fuse clips and wire fuse retainers, steel copper-clad silver-plated fuse clips should be used. Do not remove the wire retainers until the new steel fuse clips are on board for substitution. Tighten the fuse-clip barrel nut until the arch in bottom of the steel fuse clip is drawn flat.

JACKPLUG

The plug connected to the end of the cable on a sound-powered telephone headset-chestset. When plugged into a jackbox, it connects the set to a sound-powered telephone circuit.

Singlemode

The point at which a single-mode fiber propagates only one mode depends on the wavelength of the light carried. Single-mode operation begins when the wavelength approaches the core diameter. At 1300 m the fiber permits only one mode. It becomes a single-mode fiber.

Instruments

The pointer of each should read zero (except switchboard instrument synchroscopes) when the instrument is disconnected from the circuit. The pointer may be brought to zero by external screwdriver adjustment. CAUTION: This should not be done unless proper authorization is given.

Power Distribution Section

The power distribution section of the switchboard (panels 1 through 4) is supplied with power from as many sources as possible. The power distribution section, in turn, supplies power from its various buses to several IC and FC circuits. Power distribution by the switchboard of a particular ship depends on the requirements of the IC and FC systems installed.

POWER MONITORING INSTRUMENTS

The power monitoring instrumentation consists of voltmeters, ammeters, and frequency meters. There are also phase selector switches for the voltmeters and the ammeters. These various meters are used to check the voltage, current, and frequency of each input power bus and the presence of grounds.

Power Supply

The power supply chassis is mounted on the left of the electronic control chassis in the Electronic Control Assembly cabinet as shown in figure 4-32 and is accessible without removing the chassis from the control cabinet. The power output and regulator transistors and zener diodes are mounted separately on the frame member at the rear of the cabinet and the cabinet is used as a heat sink. The chassis contains two circuit boards, three transformers, and other directly-mounted components. A terminal board on top provides connection points for the cable coupling the power supply to the transistors located on the rear frame member. A connector is provided to permit easy removal or replacement of the power supply.

Power Supply

The power supply converts the normal 24-volt d-c shipboard power to voltages which meet the power requirements of the Mark 27 Gyrocompass. Where the shipboard power source is a-c power, the Mark 27 Power Converter is used to produce the 24 volts d-c for the input to the power supply.

POWER SUPPLY

The power supply is basically a full-wave rectifier receiving its power through switch S1 (fig. 5-16) and the fuses on the face of the amplifier. A neon glow lamp and a volume control potentiometer are also located on the face of the amplifier. The amplifier operates on 115-volt, 60-Hz, single-phase power, which is normally supplied by the ship's local lighting panels.

MK 23 MOD C-3 GYROCOMPASS SYSTEM

The power supply unit and the power supply control unit, together with a 120-volt dc battery, are used to form a standby power supply for the compass. This standby power supply provides uninterrupted 120-volt, 400-Hz, 3-phase power to the compass for a limited period of time if the normal ship's supply fails. If the normal ship's supply fails, a red light located on the power supply control unit will come on. When the compass is being supplied power from the standby power supply, power will be cut off to some of the remote repeaters.

Gyro Motor

The preload is maintained by two threaded clamps, one on each end of the gyro rotor. In addition, the clamp presses a wick (held in a retainer ring) against the inner race of each bearing. The wick feeds oil to the bearings from a felt reservoir in the lower part of the gyrosphere. The outer race rotation results in a flow of oil from the inner race to the outer race where the excess oil is centrifugally thrown off. The excess oil collects on the inner surface of the sphere and runs down the inside of the sphere to the oil reservoir. By this means the required oil lubrication is achieved.

System Capabilities and Interfaces

The primary capabilities and purpose of NAVSSI AN/SSN-6 Block 3 system is to distribute common position, velocity, time, and almanac data to onboard Command & Control and Combat Systems. This is done in real time, with the Global Positioning System (GPS) as the primary source of navigation data.

FUNCTIONAL DESCRIPTION

The primary function of the stabilized gyrocompass set is to produce precision analog dual-speed roll, pitch, and heading signals for use by the ship's equipment. The outputs are available in all modes during normal operation and battery backup. When operating on inverter produced single-phase power, only vital heading and its synchro reference are available. For the stabilized gyrocompass to operate, it requires certain electrical inputs from the ship. These inputs are 115-volt ac, 400-Hz, single-phase synchro excitation; 115-volt ac, 400-Hz, 3-phase primary power; underwater log data with reference voltage; and 24-volts dc provided internally by the battery set and used during the loss of 3-phase input power.

FAULT INDICATORS

The processor monitors the control signals from the control indicator. When erroneous control output signals are detected, the processor sends out signals that energize the FAULT DI indicator and the ALARM indicator.

MAINTENANCE OF CABLES

The purpose of cable maintenance is to keep the cable insulation resistance high. Cables should be kept clean and dry, and protected from mechanical damage, oil, and salt water.

MAINTENANCE OF CABLES

The purpose of insulation on electrical cables and equipment is to (1) isolate current-carrying conductors from metallic and structural parts and (2) insulate points of unequal potential on conductors from each other. The resistance of such insulation should be sufficiently high to result in negligible current flow through or over its surface.

Fiber Cladding

The relationship between the core and the cladding is an important one. First, the surface where the core meets the cladding must be very smooth in order to achieve regular reflection. Otherwise, the light would scatter when it strikes the surface. Secondly, in order to minimize signal loss the core material must be denser than the cladding material.

Accepting or Rejecting Fixes

The reset mode allows the operator to select how automatic fixes are accepted or rejected, enables review of last accepted fix data, and enables review and manual acceptance of pending fixes that the system has rejected as unreasonable. The Fix Review mode can be selected from the Mode menu, Reset Mode function. The mode selected on this menu determines how the system involves the operator in the review and acceptance of fixes from external position sensors. Manual fixes can be entered into the system at any time using the Mode menu, Fix function. When fixes are entered manually, the system checks the fix data for reasonableness in the same manner as for fixes received from external position sensors. If the manually entered fix data is determined to be invalid, an appropriate fault code and a Reset Data menu are displayed. This menu allows the operator to review the entered fix data and either force acceptance or discard the data. At any time, the operator can review the data for the last position fix accepted by the system. This function is selected from the Display menu, Page 3, Reset Data function. Figure 4-57 presents an outline of the various states associated with the position fix functions.

SWITCHING CIRCUIT

The restoration of K1 will result in normal communications at sound-powered level between all stations. The amplifier is effectively bypassed. The advantage of this circuitry is that any casualty, such as loss of power, will allow normal sound-powered communications to continue.

SIGNAL DEVELOPMENT

The roll and pitch sine and cosine signals from the resolver preamplifier are amplified, buffered, and converted to standard three-wire format by the synchro signal amplifier. The data leaves the synchro signal amplifier as S1, S2, and S3 synchro data.

SIGNAL DEVELOPMENT

The roll, pitch, and heading (in some publications referred to as azimuth) located in the IMU gimbal are excited by 26 volts, 4.8 kHz when the gimbal is caged, or by 26 volts, 400 Hz during normal operation. Both resolver excitation levels are provided by the servoamplifier. Each resolver has two outputs, which represent the sine and cosine of the angular displacement of its respective rotor shaft. These outputs are sent back to the servoamplifier when the gimbal is caged. When the gimbal is uncaged, during normal operation, the outputs are sent to the resolver preamplifier.

SELECTOR SWITCHES

The selector switch is a multiple rotary switch designed for use in connection with sound-powered telephone systems. The switch is constructed with 2 sections and has 16 stationary contacts for incoming lines on each section. The rotor has a movable contact and is driven directly from the shaft attached to the handle, which has an indexing mechanism for selecting the desired circuit. The switch has a built-in jack outlet connected to the rotor contacts.

Records

The service record book remains with the master gyrocompass throughout its service life. Should the compass be removed from the ship, its service record book accompanies it.

Servo Amplifier

The servo amplifier is an integral part of the follow-up system used for the Mark 27 Gyrocompass. The amplifier has the necessary voltage and the power amplification of the follow-up pickoff signal to drive the azimuth n1otor and n1aintain alignn1ent of the phanton1 yoke with the sensitive element. It also provides stabilization and quick response to the overall follow-up system. It uses other sources of signals to aid in leveling the gyrocompass or to slew it in azimuth during starting.

Servo Amplifier

The servo amplifier is located in the electronic control assembly where necessary interconnections are made between the amplifier, signal source, and power supply. With the exception of the power output transistors, the amplifier components are mounted on a plug-in, subassembly board on the right side of the electronic control assembly as shown in figure 4-32 and easy access to all circuit points is possible by removal of the chassis from the front of the cabinet. The power output transistors are physically mounted on the rear of the cabinet frame which affords heat dissipation.

Reference Speed Selection

The ship's EM log input is changed from synchro format to sine and cosine values by the Scott "T" transformers in the A/D multiplexer transformer. The EM log sine and cosine signals are selected by the A/D multiplexer and converted to a tangent value, in digital format, by the A/D converter. The EM log tangent signal is then applied to the processor. When the REF SP switch is set to OFF, the processor ignores the EM log inputs and the gyro operates in the free inertial state. When the REF SP switch is set to EM LOG, the processor tells the software program to implement gyro operation, damped by the EM log velocity information.

SHIP'S SERVICE POWER DISTRIBUTION SYSTEM

The ship's service generator and distribution switchboards are interconnected by bus ties. This interconnection allows any distribution switchboard to feed power from its generators to one or more of the other switchboards, allowing the generator plants to be operated in parallel. The power distribution to loads can be directly from the generator and distribution switchboards. The power distribution can also be from distribution panels to small loads or from load centers to larger loads. Figures 3-1 and 3-2 are examples of two typical power distribution systems found on some ships.

SINGLE CABLE STRAP

The single cable strap is the simplest form of cable support. The cable strap is used to secure cables to bulkheads, decks, cable hangers, fixtures, and so on. The one-hole cable strap (fig. 2-48, view A) may be used for cables not exceeding five-eighths of an inch in diameter. The two-hole strap (fig. 2-48, view B) may be used for cables over five-eighths of an inch in diameter. The spacing of simple cable supports must not exceed 32 inches center to center.

Principles of Operation of the Receiver Unit

The sound-powered receiver unit reverses the transmission process. The alternating voltage generated in a transmitter unit is impressed upon the receiver coil, which surrounds the armature of the receiver unit. The resultant current through the coil magnetizes the armature with alternating polarity. An induced voltage in the coil of the transmitter unit (fig. 5-9, view A) causes a current to flow in the coil of the receiver unit (fig. 5-9, vie w B), magnetizing the free end of the armature arbitrarily with north polarity. The free end of the armature is repelled by the North Pole and attracted by the South Pole. As the direction of the current in the receiver reverses, the polarity of the armature reverses. The position of the armature in the air gap reverses, forcing the diaphragm inward. The diaphragm of the receiver unit vibrates in unison with the diaphragm of the transmitter unit and generates corresponding sound waves in the receiver unit.

Speed Unit

The speed unit contains the necessary components to produce an electrical signal proportional to ship's speed. Speed information is received from the ship's underwater log equipment or is set in manually by the ship's dummy log system. The speed range of the unit is 0 to 40 knots.

MODES OF OPERATION

The stabilized gyrocompass set has three modes of operation: automatic calibration (AUTO CAL), navigate (NAV), and directional gyro (DG). At equipment turn-on, there is a leveling sequence that provides for equipment leveling and initial calibration.

Leveling Sequence

The stable element leveling sequence is initiated upon application of power to the equipment. This is accomplished by moving the MODE switch out of the POWER OFF position. The major elements of the leveling sequence are stable element caging, digital course leveling, tine leveling, gyrocompassing, and calibration.

MK 23 MOD C-3 GYROCOMPASS SYSTEM

The starting and stopping procedures for the compass are basically the same as for the Mk 23. Instructions for starting and stopping the compass under normal conditions are given on the instruction plate (fig. 4-24) located on the front of the control panel. Make sure the ON-OFF switch located in the power supply control unit is in the ON position before starting the compass. For additional information on starting and stopping the compass, refer to the manufacturer's technical manual.

Phone/Distance and Station-to-Station Lines

The station-to-station line is used for communications between the delivery and receiving cargo transfer stations on each ship. This line is also made up and kept by the ship's deck division. The line is identical to the bridge-to-bridge line, except it doesn't have any distance markers attached to it.

TYPE JF

The switch decks are made of molded nylon material. Be careful in soldering the leads to the switch contacts. Too much heat passing back to the switch deck will destroy the switch deck or damage the insulation between adjacent contacts.

Rotary Snap Switches

The switch type designation indicates its current rating (1SR is 10 amperes, 3SR is 30 amperes, and so on); number of poles (3SR3 is 30 amperes, 3 poles); switching action (1SR3A is single-throw; that is, on-off); mounting style (1SR3A1 is front-mounted, back-connected); and enclosure (3SR4B1-3 is watertight). (An exploded view of a type 6SR snap switch is illustrated in fig. 2-5.)

MAIN IC SWITCHBOARD

The switchboard consists of a power distribution section and an ACO section. The power distribution section may be subdivided into various buses, depending on the individual ship requirements. Figure 3-4 is an example of a front-service switchboard that is currently installed aboard some naval vessels. The distribution section consists of panels 1 through 4, while the ACO section consists of panels 5 and 6.

MAIN IC SWITCHBOARD

The switchboard is a type 1, deck-mounted, front-serviced, enclosed, box-type structure. The structure is divided into panels, with each panel having a hinged door. Lightweight items, such as switches, meters, fuse holders of up to 60-ampere capacity, and other equipment, are mounted on the front of the hinged doors. The doors are hinged on the left-hand side and are provided with two "dog-type" latches on the right-hand side and a door stop assembly.

Steering Gear Room Local IC Switchboard

The switchboard receives its 120-volt, 60-Hz, single- or 3-phase normal input from the steering-power transfer switchboard or one of the ship's power panels located in the steering gear room. A local emergency lighting circuit provides emergency power. This switchboard includes an ABT device, power available indicator lights, supply switches, and ACO switches.

PLOTTERS TRANSFER SWITCHBOARDS

The switchboards consist of one or more SB-82/SRR panels (fig. 5-19, view A). Each panel consists of five vertical rows of 10 double-pole, single-throw switches. Each row on the panel is connected to a sound-powered circuit, and each switch on the panel is connected to a sound-powered jackbox. The switches are continuously rotatable in either direction. Several different sound-powered jackboxes and circuits are connected to these switchboards, thus permitting the plotters to be shifted from one circuit to another quickly and efficiently as the situation dictates and eliminates the necessity of installing multiple-circuit phone boxes at each station.

System Capabilities and Interfaces

The system provides consistent, accurate, timely Position, Velocity, and Time (PVT) data to all navigation dependent shipboard systems. It provides autonomous almanac data to the Tomahawk missile system. It also provides, voyage planning and voyage management functionality, using Digital Nautical Charts (DNCs) and other National Imagery and Mapping Agency (NIMA) products. Users include other navigation systems; Command, Control, Communications and Computer Intelligence, Surveillance, and Reconnaissance systems; weapon systems; and the shipboard navigation teams. This composite PVT enhances the ability of surface ships to perform navigation, ship control, and combat missions. The AN/SSN-6 composite PVT will normally be the most accurate information onboard.

Maintenance of Gyrocompasses

The technical manual sent with the WSN-2 is laid out in such a manner as to greatly assist the troubleshooter. You should carefully study these technical manuals before starting any maintenance action.

Armored Cable

The term armored cable refers to a cable that has an outer shield of weaved braid. The braid is made of aluminum or steel and applied around the impervious sheath of the cable. This weaved braid helps prevent damage to the cable during installation.

Watertight Cable

The term watertight cable indicates standard cable in which all spaces under the impervious sheath are filled with material. This eliminates voids and prevents the flow of water through the cable by hose action if an open end of cable is exposed to water under pressure.

Bus Transfer Equipment

The test should include operation initiated by cutting off power (opening a feeder circuit breaker) to see if an automatic transfer takes place. When testing bus transfer equipment, you should follow the same precautions given for testing circuit breakers. The tests and inspections are normally outlined on MRCs.

ABT DEVICE

The test switch is used to test the ABT for its automatic transfer capability. The control disconnect switch must be in the AUTO position when using the test switch.

BUS FAILURE ALARM UNIT

The type IC/E1D1 electronic signal unit (fig. 3-26) is designed as a bus failure alarm. The unit contains an electronic solid-state oscillator, which drives a 2-inch howler unit that provides an audible signal upon loss of power on the supervised bus. A red drop flag installed on the unit provides a visual signal upon loss of power.

TYPE J

The type J multiple rotary selector switch (fig. 2-8) consists of an equal number of rotors and pancake sections. The number of sections required in the switch is determined by the individual application. A shaft with an operating handle extends through the center of the rotors. The movable contacts are mounted on the rotors, and the stationary contacts are mounted on the pancake sections. Each section consists of eight contacts, designated A to H, and a rotor with two insulated movable contacts spaced 180° apart. Each movable contact is arranged to bridge two adjacent stationary contacts. The switch has eight positions. A detent mechanism is provided for proper alignment of the contacts in each position of the operating handle.

TYPE JR

The type JR switch (fig. 2-9) is installed on recent IC switchboards. This switch is smaller than the J switch. This feature saves switchboard space. This feature also makes disassembly a lot easier. Remember, however, that a faulty switch should be repaired only when immediate replacement is not possible, and it should be replaced at the earliest opportunity. The JR switch is divided into four types: 1JR, 2JR, 3JR, and 4JR.

SPECIAL USE

There are many different types of flexing service cable designed for special requirements of certain installations, including type LSTTOP and casualty power cables. Type TRF is used for arc-welding circuits.

SPECIAL USE

There are many shipboard electrical circuits where special requirements of voltage, current, frequency, and service must be met in cable installation. There are also other circuits where general use, non-flexing service cable may meet the necessary requirements, yet be economically impracticable. For these reasons, there are many different types of non-flexing service cable for specialized use, such as degaussing, telephone, radio, and casualty power.

TYPES OF SWITCHES

There are many types and classifications of switches. A common designation is by the number of poles, throws, and positions. The number of poles indicates the number of terminals at which current can enter the switch. The throw of a switch signifies the number of circuits each blade or contactor can complete through the switch. The number of positions indicates the number of places at which the operating device (toggle, plunger, and so on) will come to rest.

Switchboard Components

There are several components used with the main IC switchboards. The need for these components range from providing a means of receiving and distributing power to the various IC systems to alerting watch standers of existing troubles within the systems. The components commonly used with main IC switchboards are ABT devices, switches, bus failure alarm units, fuses and fuse holders, lamps and lamp holders, synchro overload transformers and indicators, and power monitoring instruments.

Singlemode

There are three types of single-mode optical fibers usually found in typical telecommunication and data networking applications. In addition to standard single-mode fibers there are also dispersion-shifted (DS) fibers and nonzero-dispersion-shifted (NZ-DS) fibers. The purpose of these fibers is to reduce dispersion in the transmission window having the lowest attenuation. Normally, attenuation is lowest at 1550 m and dispersion at the 1300 m windows.

Sound-Powered Headset-Chestsets

There are two other types of headset-chestsets used with the sound-powered telephone system. They are the H-201/U and the H-202/U. 5-22

Power Supplies

There are two power supplies to the AN/WSN-2 gyrocompass. These are the backup power supply and the normal power supply.

IC/N Thermostatic Switches

Thermostatic, or temperature-operated, switches are usually SPST, quick-acting, normally open switches. Each switch contains a bellows that works against an adjustable spring, Y (fig. 2-14). The spring causes the contacts to close automatically when the operating temperature exceeds a specified value. The bellows motion is produced by a sealed-in liquid that expands with rising temperature. The sensitive element containing this liquid may be built into switch or located in a remote space and connected to the switch by a capillary tube. The temperature range at which the switches operate is adjustable at X (fig. 2-14).

CABLE MARKING

These cable designations include (1) the service letter, (2) the circuit letter(s), and (3) the cable number. The SERVICE is denoted by the letter C, which is the designation for all cables and circuits that comprise the IC system in naval ships. Each circuit is distinguished by a single letter or double letters. These letters identify the cable as a part of one of the numerous IC circuits. If two or more circuits of the same system are contained in a single cable, the number preceding the circuit letter or letters is omitted. The cable number is the number of the cable of the particular circuit.

Operation

These instructions will enable operating personnel to start and settle the compass in azimuth in a minimum of time under all sea conditions. Although operation of the Mark 27 Gyrocompass does not require continuous attention to the controls and adjustments, operating personnel should have a full knowledge of the meaning and purpose of the various indicating lamps, meters, switches, and alarms.

FUSE PANEL

These panels utilize the FHL 57G fuseholder, designed for circuit loads from 1 to 16 amperes and voltages up to 125VAC. A blown-fuse indicator lamp is provided for each fuse. The fuses protect all switchboard circuits that distribute power and excitation to peripheral equipment and components within the switchboard.

Linear Movement Switches

These switches are assembled from four basic modules. The front module consists of the front panel, front plate and handle. The mechanism module consists of the drive gears, the Geneva driver indexing mechanism, star detent, stop screw, drive shaft and related mechanical components. The housing module serves as a support bracket to maintain the mechanical integrity of the switch assembly. The contact assembly module contains the connector terminals that are integral with the stationary plate and a linear movement plate, containing contacts that mate with those on the stationary plate. Remote-operated switches also have the drive motor assembly containing the necessary mechanisms to drive the switch and circuitry to command the motor.

Mechanical Switches

These switches will open or close a circuit with a very small movement of the tripping device. They are usually of the push-button variety, and depend on one or more springs for their snap action. For example, the spring of the sensitive switch is a beryllium copper spring, heat-treated for long life and unfailing action. The simplicity of the one-piece spring contributes to the long life and dependability of this switch. The basic sensitive switch is shown in figure 2-15.

Stuffing Tubes

This allows a single-size stuffing tube to be used for a variety of cable sizes, and makes it possible for 9 sizes of nylon tubes to replace 23 sizes of aluminum, steel, and brass tubes.

RELAY PANEL

This assembly provides the switchboard with the capability to respond to external commands in order to automatically transfer data.

IC/D Interrupted Call Signal Station

This call signal station is used along with the noninterrupted call signal station in a space where two different circuits are required; thus providing different audible signals to alert personnel as to which station is being called.

Maintenance Concept

This feature, along with optical calibration data which is stored in Non-Volatile Random Access Memory (NVRAM) and Indexer Assembly alignment calibration data stored in a PROM (U20) on the Sensor Interface Circuit Card Assembly (CCA) (A13) in the card rack, allows the IMU to be replaced without the requirement to optically realign the system. In addition, the system uses a passive cooling design, eliminating the need for periodic shipboard maintenance for air-filter replacement.

IC/D Interrupted Call Signal Station

This station is identical to the noninterrupted station, except the hand-operated magneto generator has been modified to generate a pulsating voltage. When the generator handle is cranked, the pulsating voltage produced will provide an interrupted howl at the selected station.

TIME-DELAY TYPE

This type is essentially the same as the instantaneous type with the addition of a time-delay device. The time-delay device may be an oil dashpot with a piston attached to the tripping armature of the relay. This piston has a hole through which oil passes when the tripping armature is moved due to the excessive motor current. The size of the hole can be adjusted to change the speed at which the piston moves for a given pull on the armature. For a given size hole, the larger the current, the faster the operation. This allows the motor to carry a small overload current for a longer period of time than a large overload current.

RELAY TESTER

This unit permits the testing of 8- and 16-pin relays in the switchboard. Figure

POWER AVAILABLE INDICATOR.

This unit provides a visual indication of power supplied to the switchboard.

ABT DEVICE

Three-way transfers indicate that the ABT is capable of transferring the load between three sources of power available to the ABT. These three sources of power are identified as normal, alternate, and emergency. Either the normal or alternate source may be selected as the preferred source.

Action Cut-out (ACO) Section

Through the proper manipulation of switches, either the main or the auxiliary gyrocompass may be selected as the information-sending device to the many gyrocompass repeaters of the system. In addition, each of the individual repeaters in the system may be cut in or out of the system without having any adverse effect on the operation of the system. The switches for the other systems may be used in the same manner as those for the gyrocompass.

Time-Delay Fuses

Time-delay fuses are used in motor supply circuits, for example, where overloads and motor-starting surges of short duration exist. A conventional fuse of much higher rating would be required to prevent blowing of the fuse during surges. Because of its high rating, this fuse could not provide necessary protection for the normal steady-state current of the circuit.

Point-to-Point Calls

To answer an incoming point-to-point call, you should perform the following procedure: 1. Set the PLACE CALL/ANSWER switch to the ANSWER position (the switch should already be in the ANSWER position). 2. Remove the handset from its holder and depress the handset press-to-talk switch and acknowledge the call. 3. When the call is completed, return the handset to its holder.

Looping

To create a loop, four or more point-to-point, conference calls, or both must be in progress at the same time and a particular and predictable relationship must exist among the station numbers of the called stations. The numbers of the calling stations are immaterial since the cable pairs carrying the calls are those assigned to the called terminal station. The called station is permanently connected to those pairs that carry the call, while the calling station connects itself in parallel to those pairs by the use of the station selector switch.

Testing Cables

To ground test a multiconductor IC cable with a Megger, proceed as follows: 1. Check to see that the cable armor is grounded by measuring between the cable armor and the metal structure of the ship; normally, grounding has been accomplished by cable straps. If a zero reading is not obtained, ground the cable armor. 2. Select one conductor to be tested, and connect all other conductors in the cable together. Ground them with temporary wires or jumpers. 3. Measure the resistance of the conductor being tested to ground. Apply test voltage until a constant reading is obtained. Crank hand-driven generator-type Meggers for at least 30 seconds to ensure a steady reading. 4. Repeat steps 2 and 3 as necessary to test each conductor to ground.

IC/D Noninterrupted Call Signal Station

To operate the station, you simply turn the rotary selector switch to the station to be called and crank the magneto generator handle. The howler (a modified sound-powered telephone receiver unit) at the selected station will produce a high distinctive howl. The howl will continue for as long as the calling station generator is cranked. The attenuator is used to control the volume of the individual howler at its respective station. Each EM circuit station is equipped with an IC/D call signal station. Figure 5-22 is an elementary wiring diagram of the 2EM (ship control) circuit.

Linear Switches and Switching Equipment

To perform these functions, Switchboards also provide circuit protection and change voltage levels to affect compatibility between systems.

LOSS OF SENSITIVITY

To test a handset for loss of sensitivity, you should blow air into the transmitter. It is not necessary to press the talk switch because the transmitter and receiver are permanently connected in parallel. If no sound is heard, either the transmitter or the receiver is defective. The easiest method to determine which unit is defective is to have someone talk into another phone on the circuit while you listen to both the transmitter and receiver of the handset. If the talker's voice is heard on one of the units but not the other, you should replace the unit on which the voice is not heard because it is defective. If the talker's voice cannot be heard on either unit, and the telephone circuit being used is known to be good, the fault may be traced to the line cord, switch, or internal handset circuits.

Circuit Breakers, Contractors, and Relays

To test normally operated circuit breakers, simply open and close the breaker to check mechanical operation. For electrically operated circuit breakers, the test should be made with the operating switch or control to check both mechanical operation and control wiring. Care must be exercised during these operating tests not to disrupt any electric power supply vital to the operation of the ship, nor to endanger ship's personnel by inadvertently starting or energizing equipment being repaired.

Illumination Control

Two circuits control the level of illumination of the control-indicator's panel lighting and indicators. These circuits are illustrated in block diagrams in figures 4-39 and 4-40.

SELECTOR SWITCHES

Type A-26A sound-powered telephone selector switches (fig. 5-18) are located throughout the ship at control and operating stations served by more than one sound-powered telephone circuit. The selector switch enables the operator to connect the sound-powered telephone to any one of several circuits brought to the switch without having to change from one jackbox to another.

Maintenance of Relays

Under normal operating conditions, most relay contacts spark slightly; this will cause some minor burning and pitting of the contacts.

UNIT 3

Unit 3 (fig. 5-27) is a console-mounted terminal station consisting of four separate components: BCP console 3A1, hand-ringing generator 3A2, audible alarm BZ-240/WTC-2(V), and handset HS1. BCP console 3A1 and hand ringing generator 3A2 serve the same purpose as the cover assembly in unit 1. The audible alarm component houses an electrical horn for remote audible signaling.

UNIT 5

Unit 5 is a standard H-200/U sound-powered telephone headset-chestset. Unit 5 is used with unit 4 and may also be connected to a terminal station equipped with a jack.

UNIT 6

Unit 6 (fig. 5-28) provides a means of connecting an extension visual signal device to ship's power in areas where such a device is required. Unit 6 is comprised of a relay assembly mounted inside an enclosure assembly. The dc voltage from a calling terminal station activates the relay, which connects the 115-volt power circuits to as many as three extension visual signal devices.

UNIT 7

Unit 7 (fig. 5-30) is used to test the terminal stations, it has the capability of testing the continuity of the station selector switches and associated wiring of the terminal stations. The test set is a portable bench top unit that mainly consists of an ON/OFF toggle switch, a transformer, and 24 light emitting diodes to test the continuity of the two station selector switches on the terminal stations.

UNIT 8

Unit 8 (fig. 5-31) provides an audible signal to a location remote from a terminal station when additional audible signaling is required due to high noise levels or physical barriers to sound near a terminal station. The audible alarm consists of an electrical horn mounted within the component. The audible alarm is also supplied as one of the components for unit 3.

SHIP'S COURSE INDICATORS (REPEATERS)

Units may be designated as single-speed or 1 and 36 speed. Single-speed units contain one synchro control transformer in larger units and one synchro receiver in miniature units. The 1 and 36 speed units provide greater accuracy in reading and contain two control transformers. In the 1 and 36 speed, coarse control is 1 speed and fine control is 36 speed. Units also may be divided by power requirements with some using 60 Hz and others using 400 Hz.

SPERRY MK 23 GYROCOMPASS SYSTEMS

Unlike the mechanical gyrocompass, which uses weights that are affected by gravity to cause the desired period of damping, the Sperry Mk 23 gyrocompass uses a special type of electrolytic bubble level (gravity reference), which generates a signal proportional to the tilt of the gyro axle. This signal is then amplified and applied to an electromagnet which applies torque about the vertical and/or horizontal axes to give the compass the desired period and damping. The gyrocompass is compensated for speed error, latitude error, unbalance, and supply voltage fluctuations. An electronic follow-up system furnishes accurate transmission of heading data to remote indicators.

MAKING THE GYROSCOPE INTO A GYROCOMPASS

Up to this point, we have discussed the basic properties of a free gyroscope. Now, we will discuss how we use these properties, rigidity of plane and precession, to make a gyroscope into a gyrocompass. The first step in changing the gyroscope to a gyrocompass is to make a change in the suspension system. The inner gimbal that holds the gyro rotor is modified by replacing it within a sphere or case (fig. 4-11, view A), a necessary feature that protects the rotor. A vacuum is formed inside the sphere to reduce air friction on the spinning rotor. The next step is to replace the simple gyroscopic hose with what is called a phantom ring (fig. 4-11, view A). The difference between the simple base and the phantom is that the phantom is turned by a servomechanism to follow the horizontal plane of the rotor's axle, while the simple base remains fixed in its position. The phantom ring allows the outer gimbal (vertical ring) (fig. 4-11, view A) the freedom to turn and to tilt. These modifications enable the gyroscope to maintain its plane of rotation as long as it spins and nothing touches it. We have modified the basic suspension system to enable us to convert the gyroscope to a gyrocompass. Now, we must make it seek out and point to true north. For the purposes of this explanation, true north is the direction along the meridian from the point of observation to the North Pole.

DIGITAL COARSE LEVELING

Upon completion of the caging sequence, all integrators and biases and the alpha (OC) angle (the alpha angle is the angular difference between the stable element's [north-south] axis and true north) are set to zero, and digital course leveling is initiated. Normally, digital coarse leveling requires 1 minute. This time, however, may be lengthened by loop settling delays. Completion of digital coarse leveling is determined by the velocity error signal. When the absolute values of the velocity error signal represent less than 1/2 ft/sec, and 60 seconds have elapsed, digital coarse leveling is complete, and fine leveling is started.

STABLE ELEMENT CAGING

Upon energizing and for 10 seconds thereafter, gyro spin power is inhibited by the software program and the stable element is caged. At the end of the delay, the gyros are energized with high spin power. The software program allows 60 seconds for the gyros to gain speed and then perform the gyro synchronization test. If the synchronization test is passed, the program examines the output of the X accelerometer (fig. 4-39) for minimum output, which indicates the platform is level. The software program then checks for proper temperature of the IMU. When the synchronization test, level check and temperature check are successfully completed, the stable element is uncaged and placed under gyro control. Gyro spin power is then set to normal low spin value.

SIGNAL GENERATOR

Used in Gun Fire Control switchboards, this unit produces audible tones at 600-Hz and 1500-Hz.and a warble frequency combing 600 and 1500 Hz. for distribution to various weapon system stations.

FUSE TESTER

Used to test fuses that have current ratings above 0.05 amperes

VOICE TUBES

Voice tubes are installed aboard ship in addition to the sound-powered telephone system to provide another way for transmitting information between designated stations. The voice tube is used to transmit voice orders and information over short distances by nonelectrical means. Voice tubes are made of 3-inch brass, thin-walled tubing fitted with mouthpieces at each end. Voice tubes are installed between the following stations aboard ship as applicable: • From the pilothouse (helmsman's station) to the navigation bridge wings (port and starboard) • From the pilothouse (helmsman's station) to the exposed conning station (top of pilothouse) • From the pilothouse chart table to the navigation bridge wing peloruses (port and starboard) • From the chart room chart table to the navigation bridge wing peloruses (port and starboard) • From the flag plot chart table to the flag bridge wing peloruses (port and starboard) • From the pilothouse to the captain's sea cabin • Push buttons are installed at the pilothouse chart table and chart room chart table and are connected to energize a bell installed at each navigation bridge pelorus (port and starboard). • Push buttons are installed at the flag plot and are connected to energize a bell installed at each flag bridge pelorus (port and starboard). • A push button and buzzer are installed in the pilothouse and captain's sea cabin, with each push button connected to energize its respective buzzer.

Stuffing Tubes

Watertight integrity is vital aboard ship in peacetime or in combat. Just one improper cable installation could endanger the entire ship. For example, if a cable is replaced by a newer cable of a smaller size and the fittings passing through a watertight bulkhead are not changed to the proper size, the result could be two flooded spaces in the event of a collision or enemy hit.

GYROSCOPIC PROPERTIES

When a gyroscope rotor is spinning, it develops two characteristics, or properties, that it does not possess when at rest: rigidity of plane and precession. These two properties make it possible to convert a free gyroscope into a gyrocompass.

Looping

When a loop is formed, the operators of the affected stations will simultaneously hear all conversations among the stations involved in the loop. The conversations will be at relatively high audio levels, making normal communications among these stations impossible.

Maintenance of Relays

When a relay has bent contacts, you should use a point bender (fig. 2-26) to straighten the contacts. The use of any other tool could cause further damage, and the entire relay would then have to be replaced.

SYNCHRO OVERLOAD TRANSFORMERS AND INDICATORS

When an overload indicator lamp is glowing, the cause of the malfunction should be investigated immediately and corrected as soon as possible. The switchboard operator can isolate the affected instrument from the circuit by operating the associated ACO switch. If the circuit malfunction cannot be determined, check the transformer setting. The indication may be the result of the overload transformer being set too low.

CABLE RACK

When applying banding material, apply one turn of banding for a single cable less than 1 inch in diameter. Apply two turns of banding for single cables of 1 inch or more in diameter and for a row of cables. Apply three turns of banding for partially loaded hangers where hanger width exceeds the width of a single cable or a single row of cable by more than one-half inch.

Watch Standing

When checking for grounds, the watch stander should compare the readings being taken with previous readings. Unusual deviations should be investigated and the cause determined. Low voltage between any phase and ground, with high voltage between the other phases and ground, normally indicates a ground on the phase with the low-voltage reading.

Testing Cables

When checking insulation resistance on circuits where semiconductor control devices are involved, the 500-volt dc Megger cannot be used. An electron tube megohmmeter is used on circuits and components where insulation resistance must be checked at a much lower potential. The megohmmeter operates on internal batteries. When circuits or components under test contain a large electrical capacity, the megohmmeter READ button must be depressed for a sufficient time to allow its capacitor to charge before a steady reading is obtained. The test voltage applied by the megohmmeter to an unknown resistance is approximately 50 volts when resistances of approximately 10 megohms are measured and slightly greater than this when higher resistances are measured.

Maintenance of Circuits

When conducting insulation tests on sound-powered circuits, open all tie switches connected to the circuit. Close all line cutout switches on associated switchboards or switchboxes. Disconnect all sound-powered telephone headsets from the circuit. Be sure the push button on all handsets connected to the circuit are open. Remove all sound-powered telephone amplifiers associated with the circuit from their cases.

Maintenance of Relays

When current flows in one direction through a relay, the contacts may be subjected to an effect called cone and crater. The crater is formed by the transfer of the metal of one contact to the other contact, the deposit being in the form of a cone. This condition is shown in figure 2-25, view A.

SOLENOIDS

When current flows through the conductor, a magnetic field is produced. This field acts in every respect like a permanent magnet having both a north and a south pole. The total magnetic flux density produced is the result of the generated mmf and the permeability of the medium through which the field passes.

Maintenance of Switches

When replacing a switch, take great care in tagging the leads to ensure proper replacement. Close supervision and proper checkout by an electrical petty officer can ensure against personal injury and equipment damage.

OPEN AND SHORT CIRCUITS

When testing the units for open and short circuits, you should use a low-voltage ohmmeter to avoid damage to the sound-powered transmitter and receiving units. Continuity tests may be made from the chestplate junction box on sound-powered headset-chestsets. Figure 5-13 is an illustration of the transmitter circuit of a sound-powered telephone headset-chestset. Figure 5-14 is an illustration of the receiver circuits. When testing the plug cable or tinsel cords of a sound-powered headset-chestset, you should disconnect them from the junction box. The normal dc resistances of the sound-powered transmitter and receiver units are 10 ohms and 62 ohms respectively. If the plug cable and tinsel cords test out satisfactorily, then you should check the capacitors.

ALARM RELAYS

When the 3-phase power input is lost or exceeds tolerances, the control monitor switches the operation to battery power and sends out an alarm signal to the circuit card containing the alarm summary logic. The alarm summary logic sends a signal to the on-battery relay, which is normally de-energized. When this relay energizes, it completes the circuit for the on-battery alarm.

TYPE JR

When the 4JR switch is in the OFF position, both indicators are connected together, but they are disconnected from the power supply.

Compass Heading Mode - MV103AC

When the DFGMC is powered up, the present declination value is displayed for two seconds, and then automatically enters the Compass Heading mode. The LCD area shows the present compass heading relative to magnetic North; no other symbols are activated. Figure 4-20 shows the LCD display at initial power-up in Compass Heading mode. The factory default declination value is 00o and the present heading is 270o.

Compass Heading Mode - MV103ACS and MV103DG

When the DFGMC is powered up, the system automatically enters the Compass Heading mode. The LCD area shows the present compass heading relative to magnetic North. No other symbols are activated. Figure 4-21 shows the LCD display in Compass Heading mode. The illustrated heading is 270o.

Reference Speed Selection

When the REF SP switch is set to DOCK, the processor tells the software program to use a zero reference velocity for damping instead of the EM log velocity input.

SYNCHRO OVERLOAD TRANSFORMERS AND INDICATORS

When the angular displacement of the synchro receiver is in excess of 17 ±3 degrees from the position of its associated transmitter, the indicator lamp connected to the transformer will glow. This displacement may be caused by an open or shorted rotor circuit, an open or shorted stator circuit, or lack of synchronism between transmitter and receiver caused by excessive bearing friction in the receiver.

MAKING THE GYROSCOPE INTO A GYROCOMPASS

When the gyro is started while pointed away from the meridian, the effect of earth rate causes it to tilt. As soon as it tilts, weight W causes precession; however, now the smaller weight, W1, also causes the gyro to precess towards a more level position, which limits the effect of precession caused by weight W. The excursions from level continue, but the dampening effect of weight W1 causes each successive oscillation to be reduced; the path of the rotor axle then will be spiral shaped (fig. 4-14).

APPARENT ROTATION OF THE GYROSCOPE

When the gyroscope axle is placed parallel to the earth's axis at any location on the earth's surface, the apparent rotation is about the axle of the gyroscope and cannot be observed. At any point between the equator and either pole, a gyroscope whose spinning axis is not parallel to the earth's spinning axis has an apparent rotation that is a combination of horizontal earth rate and vertical earth rate.

Paralleling of Circuits

When the patch cord method of paralleling is used, the following conditions may be obtained: 1. When the line cutout switches of both lines are open, the two lines will be connected together, but will not be tied in with any other station of either circuit. Figure 5-5 is an illustration of line cutout switches in the open and closed positions. 2. When the line cutout switch of only one line is closed, the two lines will be tied together and also connected to the other stations on the circuit of which the line cutout switch is closed. 3. When the line cutout switches of both lines are closed, all lines of the two circuits will be tied together.

Paralleling of Circuits

When two or more circuits are tied together, the result is to parallel as many sound-powered telephones as there are manned stations.

Watch Standing

When you are assigned the gyrocompass watch, you will be required to maintain the gyrocompass log and to respond to any alarms associated with the gyrocompass system. The gyrocompass log contains hourly readings showing the conditions of the gyrocompass and the power sources available. During an alarm condition, the compass is no longer considered reliable.

Maintenance of Relays

When you clean or service ball-shaped relay contacts, be careful to avoid flattening or otherwise altering the rounded surfaces of the contacts. A burnishing tool should be used to clean relay contacts. Be sure you do not touch the surface of the tool that is used to clean the relay contacts. After the burnishing tool is used, clean it with alcohol. Never use sandpaper or emery cloth to clean relay contacts. Many relays have been damaged or ruined because the contact points were cleaned with sandpaper or emery cloth instead of a burnishing tool. The use of sandpaper or emery cloth may cause bending of the contact springs and other damage. Excessively burned and pitted contacts cannot be repaired by burnishing.

ABT DEVICE

When you put the ABT in the manual mode, you no longer have the automatic transfer capability. You may select either the normal or emergency source of power by putting the manual switch in the position desired.

Kickpipes and Deck Risers

Where one or two cables pass through a deck in a single group, kickpipes are provided to protect the cables against mechanical damage. Steel pipes are used with steel decks, and aluminum pipes with aluminum and wooden decks. When stuffing tubes and kickpipes are installed, care must be taken not to install two different metals together; an electrolytic action may be set up. Inside edges on the ends of the pipe and the inside wall of the pipe must be free of burrs to prevent chafing of the cable. Kickpipes, including the stuffing tube, should have a minimum height of 9 inches and a maximum of 18 inches. If the height exceeds 12 inches, a brace is necessary to ensure rigid support. If the installation of kickpipes is required in non-watertight decks, a conduit bushing may be used in place of the stuffing tube.

Mechanical Switches

Widely used because of their small size and excellent dependability, they are commonly called "micro switches, " or properly called sensitive switches. ("MICRO SWITCH" is a trademark of MICRO SWITCH Division, Honeywell Inc.)

Distribution Boxes

Wiring distribution boxes (fused), with and without switches that feed vital circuits should be checked annually. Tighten fuse clip barrel nuts and terminal connections. On anew ship and after a major overhaul, tighten and prick punch loose bus bar nuts on the backs of insulating bases.

Latitude Set

With the DSPL SEL switch set to LAT and the ENTER LAT switch indicator on (fig. 4-35), latitude entry is made by setting the desired latitude (hemisphere, degrees, and minutes) with the thumbwheel switch, then pressing and releasing the ENTER LAT switch indicator. The ENTER LAT switch indicator will go off and the selected latitude will be displayed on the digital display.

Net Access

headset-chestset plugged into either the station jack or an associated jackbox. To access a net using the terminal station handset, you should perform the following procedure: 1. Select the predetermined net station number on the thumbwheel switches. 2. Set the PLACE CALL/ANSWER switch to the PLACE CALL position. Do not turn the crank. 3. Depress the press-to-talk switch on the handset to establish communications with the net. 4. When finished, return the handset to its holder and set the PLACE CALL/ANSWER switch to the ANSWER position. To access a net using the headset-chestset, you should perform the following procedure: 1. Connect the headset-chestset to either the jack on the terminal station or to the associated jackbox. 2. Depress the press-to-talk switch to establish communications on the net. 3. When finished, disconnect the headset-chestset from the jack or jackbox and stow it.

Modal dispersion

is that type of dispersion that results from the varying path lengths of different modes in a fiber. Imagine three race cars all traveling at the same speed. The first car follows a straight path. The second has to zigzag back and forth and the third car travels an intermediate path. If all three cars start at the same time and travel to a finish line one mile away, they obviously will arrive at different times. The same holds true for a pulse of light injected into a fiber. Different rays will follow different paths and so arrive at different times.