2nd Engineer Electricity and Electronics
How should the shunt used in an ammeter be connected?
in series with the load and in parallel with the meter movement
What is the basic principle of operation by which a transformer works?
self-impedance
A common type of molded case circuit breaker has both thermal and magnetic trip elements. If a branch circuit breaker has only thermal or magnetic trip elements (but not both), it is common to use multiple series-connected protective devices to provide both short-circuit and overload protection. If a motor branch circuit is protected with both a thermal trip-type circuit breaker and fuses, what is the protective purpose of the fuses used in this arrangement?
short-circuit protection
Fuses are sometimes placed in series with a thermal trip-type circuit breaker. What is the purpose of a fuse used in this arrangement?
short-circuit protection
Power conversion for use in DC propulsion drive motors is accomplished by what type of converter?
silicon controlled rectifier converters
In actual applications, electrical connections associated with "R1, R2 and R3" of the transmitter to "R1, R2, and R3" of the indicators shown in figure "C" of the illustration are made by what means? Illustration EL-0092
slip rings and brushes
If the contacts of a motor starter or controller fail to drop out when the 'stop' button is depressed, what could be the cause?
stop contacts have become welded together
What do the devices labeled "L" in Panel 2 of the illustrated switchboard represent? Illustration EL- 0003
synchronizing lights used as a backup to the syncroscope for paralleling purposes
If a digital multimeter is set up as shown in figures " A " and " B " of the illustration , what is the status of the silicon diode if the display reads 5 megohms when configured as in figure " A " and the display reads infinite ( OL ) megohms when configured as in figure " B " ? Illustration EL - 0211
the diode is functioning properly
As shown in the illustrated switchboard, what is the function of the switch labeled "PFM Sel. Sw."? Illustration EL-0003
to determine power factor of either generator
What is the shape of the schematic symbol for an operational amplifier used in an analog circuit?
triangle
By what means should motor controller contacts be routinely cleaned?
wiping with a clean dry cloth
Referring to figure "3" of the illustration, what type of logic gate symbolized? Illustration EL-0035
AND gate
As shown in the illustration of an electrically operated watertight door controller, how is the motor stopped automatically when the door is wedged closed? Illustration EL-0115
Action of door closed limit switch (LSC).
Concerning the illustrated motor controller circuit, where is the location of the motor "run" indicator light? Illustration EL-0004
At the remote operating station.
When a self-excited alternator's field has lost its residual magnetism due to a prolonged idle period, it will fail to produce a voltage. Flashing the field is the procedure used to restore the residual magnetism. Using a 12 volt storage battery, how is this performed?
(A) The F+ and F- leads are disconnected from the alternator field. The F+ lead is connected the positive terminal of the battery, and the F- lead is connected to the negative terminal.
Before working on an electric cargo winch master switch or controller, what should be done?
(A) open the circuit breaker in the power supply and tag-out
What statement is TRUE concerning the Azipod propulsion system?
(B) It is an electric drive system where the propulsion motor is installed in a submerged housing capable of swiveling.
As shown in the illustrated diagnostic setup for locating a shorted field coil of a ten-pole synchronous motor, if 240 VAC/60 Hz is applied across the brushes, what would be the individual voltage drops measured across each field coil assuming that none of the field coils are shorted? Illustration EL- 0202
(C) 24 VAC
Referring to the illustration pertaining to a steering system hydraulic power unit motor controller, what statement is true concerning a response to a motor overload condition as visualized by the indicator lamps? Illustration EL-0119
(C) Run indicator lamp is ON Overload indicator lamp is ON
Before work may safely commence on a high voltage system, what must first be done after disconnection and isolation?
(C) The circuit must be tested and proved dead first with a live-line tester, then grounded.
In order for a live-line tester to be used to test and prove dead a high voltage circuit, what must be done to verify the ability of the tester to detect a voltage?
(C) The live-line tester should be checked by connecting to a known high voltage source before and after the circuit to be worked upon is tested.
Referring to the illustration of a steering gear hydraulic power unit motor controller, if the motor is drawing current no greater than full load current, what will the status of the overload relay contacts and the control relay contacts be? Illustration EL-0119
(C) The overload relay contacts will be CLOSED The control relay contacts will be OPEN
The arc resulting from the tripping of a circuit breaker is prevented from damaging the contacts. How is this done?
(C) extinguishing the arc by means of an arc chute
Under what circumstance would a hand-held portable phase sequence indicator be used should the main switchboard mounted fixed phase sequence indicator be inoperative?
(C) preparing to make the shore power connection
A 480/120 VAC step - down control transformer is configured as shown in figure " E " of the illustration . When 480 VAC is applied to the primary winding ( across H1 and H2 ) , an output of 141 VAC is produced across the secondary winding ( across X1 and X2 ) . Although the fault may ultimately result in a catastrophic failure , what hypothetical fault condition is indicated that would account for these voltages ? Illustration EL - 0123
) A few shorted turns in the primary winding )
What will be the resulting current when a voltage of 12 VDC is applied to a capacitance of 470 microfarads in figure "C" of the illustrated circuit after the capacitor has had ample time to fully charge? Illustration EL-0018
0.0 amps
What would be the total current draw of the circuit as shown in figure "A" of the illustration if the source voltage is 24 volts, the resistance for R: is 12 ohms, the resistance for R2 is 24 ohms, and the resistance for R3 is 36 ohms? Illustration EL-0032
1.33 amperes
What would be the actual rotor speed for a 4-pole three-phase squirrel-cage induction motor operating at 60 Hz if the rotor slip is 3%?
1746 RPM
As shown in figure "A" of the illustrated motor nameplate, how much current could the motor safely draw on a continuous basis at sea level without overheating? Illustration EL-0171
187 amps
What would be the total current in figure "A" of the circuit illustrated if the value of capacitor C1 was 100 microfarads, capacitor C2 was 200 microfarads and the power supply was 240 volts at 60 Hz? Illustration EL-0038
27 amps
From the information given in the illustration, what would be the ampere capacity at full load of each of the main ship service diesel-generators if operating at the rated power factor of 0.8? Illustration EL-0106
3011 amps
Propulsion AC generators creating 4160 VAC use transformers to provide nominally 120 VAC to the automatic voltage regulator. What is the turns ratio of this step-down transformer?
35:1
35. A common-emitter circuit has an input voltage of 0.1 volt, an output voltage of 2.0 volts, an input current of 0.5 milliamps, and an output current of 10 milliamps. What is the power gain?
400
In figure " 4 " of the diagram in the illustration , the three - phase step - down power transformer has a turns ratio of five to one . If a three - phase 4160 volt supply is connected to terminals " A1 - B1 - C1 " , what voltage should develop across terminals " A2 - B2 - C2 " ? Illustration EL - 0084
480 volts
Which of the listed devices is most likely to be installed on a large modern diesel-electric alternating current propulsion generator for commercial ship propulsion for the purposes of fire suppression?
A CO2 fire extinguishing system.
To keep emergency lead - acid batteries in a full state of charge for emergency use , what is normally done
Batteries are kept charged by maintaining a continuous trickle charge
In a podded azimuthing propulsion system, how is three-phase, frequency and voltage controlled power delivered to the synchronous propulsion motor stator windings?
By the use of slip rings and brushes.
As shown in figures "E" and "F" of the pictured high voltage rack mounted circuit breaker, which figure represents the circuit breaker position when in the open or tripped position? Illustration EL- 0167
C
Which of the following statements, concerning the cleaning maintenance of a brushless generator, is correct?
Cleaning of windings should be performed on a conditional basis using a vacuum or using a clean, dry, lint-free rag.
Refer to the simplified diagram of the AC synchronous electric motor drive system as shown in the illustration. The propulsion motor operates from maneuvering speed to full ahead speed in the ahead direction. The propulsion motor will not operate at any speed in the astern direction. What is most likely the problem? Illustration EL-0155
Due to a controller fault, the output of the controlled inverter fails to achieve a reversal in phase sequence.
From the information given in the illustration, which of the following statements is correct? Illustration EL-0106
During normal operation, the main-emergency bus-tie circuit breaker and any on-line ship's service generator circuit breakers are simultaneously closed.
As shown in the illustration, what statement is true concerning each of the system gateways? Illustration EL-0098
Each connects one of two redundant automation area networks with one of two redundant engine control process area networks and one of two redundant cargo process area networks.
To properly use a clamp-on-type ammeter for measuring current accurately, what must be done?
Enclose one conductor within the jaws AND make sure the jaws are closed.
Regulations require that shipboard cabling use stranded copper conductors. Why is copper a superior conductor compared to aluminum?
Even though copper is heavier in weight than aluminum, copper has less resistance than aluminum.
An AC generator produces 60 Hz at 1800 RPM. If the generator speed is increased to 1830 RPM, what will happen to the frequency in Hz?
Hz increase to 61
When placed in a magnetic field, which of the materials listed has the highest permeability?
Iron
Referring to the containership one-line distribution diagram shown in the illustration, what is the purpose of the feedback circuit breaker as used to bypass the automatic bus transfer device? İllustration EL-0014
It allows the emergency generator to feed the main bus during dead ship start-up; otherwise it is generally open and not used.
In referring to figure "A" of the illustration, what type of active filter circuit is shown? Illustration EL- 0077
Low-pass filter circuit
What is the most reliable and preferred method for determining the state of charge of a wet cell NiCad battery while it is being charged?
Measuring the battery voltage with a digital voltmeter.
As shown in the illustrated block diagram for a distributed automation system, what statement is true concerning the units labeled "ROS" which are remote operating system workstations? Illustration EL- 0096
Operator access to control functions among the various ROS locations differ depending system configuration and need.
Referring to the impressed current cathodic hull protection system shown in the illustration, if required to control the impressed current to the anodes manually by using the hand adjustment potentiometer, what parameter should be maintained at a constant value? Illustration EL-0090
Reference electrode voltage
17. With an AC synchronous electric propulsion motor driving a fixed-pitch propeller, whenever there is a direction reversal ordered from the bridge, there is a process of electrical braking used to slow the motor down before the shaft actually reverses. What is the name of this process?
Regenerative braking
Within the split-phase family of single phase motors, what are the operational characteristics of the motor shown in figure "A" of the illustration? Illustration EL-0207
Relatively low starting torque with no power factor correction
Of the following, what shipboard system is MOST likely to use the synchronous transmission system featuring a transmitter and receiver?
Rudder angle indicator system
Before any work on electrical or electronic equipment is performed, which of the following precautions should be carried out?
Secure and tag the supply circuit breaker in the open position.
The torque-speed and current-speed curves for a three-phase induction motor with a squirrel-cage rotor are shown in figures "A" and "B" of the illustration. Which of the following statements is true concerning the depicted curves? Illustration EL-0056
Starting current is approximately 4.75 times the normal full load current value.
Occasionally a synchronous motor is configured without an external shaft to drive a load. In this case, the sole purpose of the synchronous motor is improving overall power factor of an electrical distribution system. What is the name of the synchronous motor so constructed?
Synchronous condenser
Which of the listed temperature measuring devices installed on a large turbo-electric alternating current propulsion generator would be the most reliable for monitoring generator temperatures to avoid premature winding insulation failure?
Temperature sensors inserted in the stator slots for measuring stator winding temperature.
As shown in figure "A" of the illustration, with the switch closed what statement is true if "Ri" and "R" have unequal resistance values? Illustration EL-0019
The current flow through "R:" will differ from the current flow through "R2".
What type of electrical diagram for the electrical distribution system is shown in the illustration? Illustration EL-0014
The diagram is a one-line diagram.
Why must caution be exercised during the charging of flooded lead-acid storage batteries?
hydrogen gas can be liberated during charging
The winch shown in the illustration operates in any of the positions with the master switch in the "lower' direction, but will not 'hoist' in any of the master switch hoist speed positions. Which of the listed faults would MOST likely be the cause? Illustration EL-0102
The hoist limit switch (LSH) contacts across terminals 9 and 10 have failed open.
When a battery-operated megohmmeter (insulation tester) is used to perform a dielectric absorption test, the resistance is measured and recorded from each conductor to ground each minute for 10 consecutive minutes. What condition accounts for a gradual rise in resistance each successive minute?
The insulation is in good condition.
No.1 SSDG was operating in parallel with No.2 SSDG in supplying the 480 VAC main bus while sharing the electrical load evenly. As a result of a problem, if No.1 SSDG begins to motorize, but the generator has not yet tripped out by the action of the reverse power relay, what would be the indication of this?
The kilowatt meter of No.1 SSDG would drop below 0 kW.
Which of the following statements about a three-phase wye connected alternator is correct?
The line voltage is 1.73 times the phase voltage.
When a transformer is used to step down voltage, what statement is true?
The low voltage winding is the secondary coil.
Referring to the sound-powered telephone circuit shown in illustration, what statement is true concerning the button on the handset as represented by the component labeled "A"? Illustration EL- 0093
The push button is depressed for the purposes of listening and talking.
As the electrolyte level in the cells of a lead-acid battery evaporates over time, what will tend to happen the specific gravity of the electrolyte in the cells as the level drops due to evaporation?
The specific gravity of the electrolyte will increase as only the water will evaporate from the electrolyte solution.
In addition to improper brush pressure or seating, what can result in excessive sparking at the brushes of a DC propulsion motor?
improper positioning of brush rigging outside the neutral plane
An AC diesel-electric drive ship with synchronous propulsion motors has the capability for power factor correction. If the power factor associated with the main power distribution including all motors is 0.7 leading, what statement is true?
The synchronous propulsion motors are over-excited.
An AC diesel-electric drive ship with synchronous propulsion motors has the capability for power factor correction. If the power factor associated with the main power distribution including all motors is 0.7 lagging, what statement is true?
The synchronous propulsion motors are under-excited.
Which of the following statements is TRUE concerning Azipod propulsion systems?
The system integrates propulsion and steering into one function.
Which of the following statements correctly applies to bipolar junction transistors?
The three terminals are called the emitter, base, and collector.
In accordance with 46 CFR Subchapter J (Electrical Engineering), which of the following starting aids is the ONLY method allowed to ease the starting of emergency diesel-generator engines?
Thermostatically controlled electric jacket water heaters
Which of the listed statements is correct when using a digital multimeter set up as an ohmmeter?
With the test leads shorted together, a reading of 'zero' ohms will be displayed.
With what kind of starting equipment are most three-phase induction motors of five horsepower or less started?
across-the-line starters
Before electrical work can be safely undertaken, the equipment must be de-energized, locked and tagged out, and verification must be made that the circuit is actually dead. What testing device is most certain to reliably verify that a circuit is actually dead?
an autoranging digital multimeter
As shown in figure "D" of the digital power meter shown in the illustration, what type of single phase load is under test for power measurement? Ilustration EL-0256
an inductive-resistive load
As shown in figure "D" of the illustrated digital power meter, what type of single-phase load under test for power measurement? Illustration EL-0256
an inductive-resistive load
Upon failure of the normal power supply, by what means is the emergency generator placed on the line and connected to the emergency bus?
automatic bus transfer device
50. By what common means is the speed of an AC propulsion motor on a diesel-electric propulsion ship controlled?
by varying both the input frequency and voltage to the motor
As shown in figure "A" of the illustration, what would be the circuit impedance if the capacitive reactance is 10 ohms and the resistance is 10 ohms? Illustration EL-0109
capacitive 14.14 ohms
If the motor shown in the illustration will not start when the "off-run" switch is placed in the run position, which of the listed components should be checked FIRST? Illustration EL-0017
check the overload relay for tripped condition, reset as necessary
How may the unit "hertz" be best described?
cycles per second
When a fluorescent lamp has reached the end of its useful life, it should be replaced immediately. If not, what condition could the resultant flashing cause?
damaging the lamp's ballast circuit
To properly use a clamp-on type ammeter to check current flow, what must be done FIRST?
hook the jaws of the instrument around the insulated single conductor
The current at which a magnetic-type overload relay tends to trip may be decreased by raising the plunger further into the magnetic circuit of the relay. What effect does this action have?
increases magnetic pull on the plunger and requires less current to trip the relay
Periodic testing using a special sensing device may be performed to detect potentially dangerous loose or corroded bus bar and controller connections. What is the name of this testing technology?
infra-red thermography
A degree of control over the speed of a slip ring induction motor can be obtained by what means?
inserting resistance into the rotor circuit
In the diagram of the switchboard shown in the illustration, what is the function of the device labeled "Gen. Bkr. Sw."? Illustration EL-0003
it allows the alternator circuit breaker to be opened or closed remotely at the synchronizing panel
How are power transformers rated?
kilovoltamperes
9. As shown in the illustration, by what means are all the "MS" contacts opened and closed? Illustration EL-0073
magnets manual operation of the master switches
Due to the operating characteristics of the system, time lag fuses (or dual-element fuses) are necessary for use in what types of circuits?
motor starting circuits
Incandescent lamps are classified according to the shape of the bulb and the type of service, as well as the size and style of the base. How are incandescent lamps rated?
operating voltage and wattage
As shown in the illustration, what mechanism will disconnect the motor from the line in case of a sustained motor overload? Illustration EL-0080
overload relay heaters and overload relay NC contacts (OL)
Large machines undergoing a resistance insulation testing using a megohmmeter should be discharged to remove any accumulated electrostatic/capacitive/dielectric-absorption charge stored. When should this discharge be performed?
prior to and after conducting the insulation resistance check
The conversion of constant frequency power into adjustable frequency power in a modern AC propulsion drive system is commonly achieved through the use of what electronic system components?
rectifiers and thyristors
What is the function of the movable cams in a master-switch winch motor drum controller?
regulate the speed of the motor
How is the main propeller shaft rotation of a rectified DC diesel-electric drive normally reversed?
reversing the field or armature polarity of the DC motor
