Segment 4 Final Review

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A dielectric test set often used for testing capacitors is generally referred to as a _________ because of its ability to produce a high voltage or high potential.

HIPOT

When two parallel feeders are installed to each of the synchronous condensers, the conductors can be sized for _______ the value of the required ampacity.

Half

The torque reaches maximum when the rotor and stator currents are _________ with each other.

in phase

Lightning arresters are designed to provide a (n)_______ path to ground for any surge currents such as those resulting from a lightning strike.

low impedance

The formula for calculating resistance of a certain length, size, and type of wire is: R = _________.

(K*L)/cmil

What percentage of the full-load current of a thermally protected continuous-duty motor of more than one Hp can the trip current be, if the full-load current is 15 amperes?

156

A 600-volt to 200-volt transformer would become a 600-volt to __________-volt transformer if the connections were reversed.

1800

________is the process of selecting protective devices so that there is a minimum of power interruption in case of a fault or overload.

Coordination

What is the maximum deflection force in pounds for a belt in the cross-section class D?

25

What effect if any does tripping the overload relay have on the circuit when a source current is applied to the circuit ?

Current will not flow and the load will stop

All overload relays contain two separate sections, the ______ section and the control contact section.

Current-sensing

When using Table 310.15(B)(16), if the ambient temperature is above _______degrees Celsius, a correction factor must be applied to allowable ampacities for conductors.

30

If the primary current is less than two amperes for a transformer rated at 600 volts or less, the short-circuit protective device can be set at not more than _____ percent of this value.

300

Three-phase motors can be constructed to operate in either wye or _______.

Delta

Although the __________ compound motor gives a more constant speed at all loads, the motor is somewhat unstable.

Differenntial

_________ compressors are usually used in large installations.

Direct drive

Most motor circuits are protected by dual-element time-delay fuses or ______.

Dual Time Circuit Breakers

Which NEC table lists the running currents for single-phase AC motors?

430.248

High-voltage fuses are available with either an N or a(n)_______ rating.

E

In most instances, the rated load-current (RLA) is at least equal to _____ percent of the hermetic refrigerant motor- compressor's maximum continuous current (MCC).

64.1

The current draw of a precipitator is ______.

Very Low

Apparent power is generally called ______.

Volt Amps

In a pure inductive load the current will lag the voltage by _______ degrees.

90

What is the maximum operating temperature (in degrees Celsius) for Type SIS insulation?

90

When the power factor of the plant is 1.0 (unity), the kilovarmeter reads ______.

0

If you have a raceway with 35 current-carrying conductors, by what adjustment factor must you multiply the ampacity?

0.4

Assume that an inductor has an inductive reactance of 100 ohms and the wire has a resistance of 10 ohms. What is the impedance?

110

Bimetal strip-type overload relays generally permit the trip current to be adjusted to between 85% and _______% of the heater rating.

115

The ampere rating of the disconnecting means for HVAC equipment must be at least ____ percent of the sum of all the individual loads within the equipment.

115

Connections between the current and potential transformers in the high-voltage section of the unit substation and the autotransformer and meter sockets in the cabinet are made with size 12_______ wire.

12 American Wire Gage

A three-phase motor contains six poles per phase. The synchronous speed of this motor is _______ RPM when connected to 60 Hz.

1200

One option for protecting a motor-compressor from overloads and failure to start is to use a time-delay fuse or inverse- time circuit breaker rated at not more than ______ percent of the rated load current.

125

Conductors in capacitor circuits must be rated no less than ____ percent of the current rating of the capacitor.

135%

Most common squirrel-cage motors used in industry fall into the design _____ classification.

B

In most instances, the rated-load current is at least equal to 64.1 percent of the hermetic refrigerant motor-compressor's ________ current.

Branch Circuit Selection

When hermetic refrigerant motor-compressors are designed to operate continuously at currents greater than 156 percent of the rated-load current, the nameplate is marked with _______ current

Branch Circuit Selection

A(n) ______ changes AC current into DC current.

Bridge Rectifier

The tremendous popularity of mechanical refrigeration for household use in the 1930s and 1940s stimulated the development of a new series of nonexplosive and nontoxic refrigerants known as ____ of the halogen family.

Chlorinated Hydro-fluorides

is a method of removing energy in the form of heat from an object.

Circulation

The evaporator in a commercial installation normally consists of a ________ coil, through which the building air is circulated by a motor-driven fan.

Fin Tube

The approximate starting current of a squirrel-cage motor can be determined by multiplying the kVA rating listed in Table 430.7(B) by the _______ rating and then dividing by the applied voltage.

Horsepower

In a machine that has a 3-phase motor rated at 460 volts, the current required by that machine is based on the ______ of the motor.

Horsepower Rating

_________loss is caused by the continuous aligning and realigning of molecules, which produces heat due to friction.

Hysteresis

The temperature ratings of devices such as circuit breakers, fuses, and terminals are found _______.

In UL Product Directories

a synchronous-type motor is operated at 90 percent power factor, the rated full-load current in the table is to be _______.

Increased By 10%

When current begins to flow through a(n) , a magnetic field expands around the _______.

Inductor

A factor that determines the amount of current a conductor is permitted to carry if the type of _________ used, which is the nonconductive covering around the wire

Insulation

Most motor circuits are protected by dual-element time-delay fuses or ______.

Inverse-time circuit breakers

The main parts of a precipitator are the ______, collector cells, and power supply

Ionizer

_______switches are indicated by drawing a wedge shape below the movable contact of a switch symbol.

Limit

A capacitor does not require a separate disconnect means if it is connected to the _____ side of the motor overload protective device.

Load

Two-phase motors that are especially designed for_______________ applications use the same rules for determining full-load currents as single-phase motors.

Low speed-high torque

The rates charged by the power company for the energy used are based on the readings of the meter registers and the______ indicators.

Maximum Demand

The ___________ protective device is determined by multiplying the rated-load current, or the branch-circuit selection current of the hermetic refrigerant motor-compressor, by 225 percent and then adding all concurrent loads such as electric heaters, motors, and so on.

Maximum Overcurrent

Air-cooled condensers use _______ to drive air across the condensing coil.

Motor Driven Fan

The correct tension for a belt in the cooling unit drive can be determined from the ________.

Motor Manufactures literature

Air-conditioning and refrigeration equipment is required by NEC® 440.4(A) and (B) to be marked with a ______ marked with the maker's name, the rating in volts, frequency and number of phases, and other information.

Nameplate

Most dual-voltage motors bring out _______ "T" leads at the terminal box.

Nine

Most capacitors used in industry, especially for power factor correction, are called ______ capacitors.

Non-Polarized

If a contact is to be drawn ____________ it is drawn so that the movable contact is above and touching the stationary contact.

Normally Closed

What does the abbreviation NO stand for with reference to switch contacts?

Normally Open

If the symbol shows the movable contact touching but below the stationary contact, this indicates that the switch is ______.

Normally open held closed

After the conductors have been installed in conduits or raceways, it is accepted practice to test the installation for grounds and shorts. This test requires a(n) _________.

Ohmmeter

The motor overload size is to be determined by using the current listed _______.

On the nameplate

_______ are intended to open the circuit when the current exceeds the full-load current rating of the motor by 115 percent to 125 percent.

Overloads

Materials that increase their resistance with an increase of temperature have a _________ coefficient of temperature

Positive

One method of removing oil mist is by the use of ______ units.

Precipitation

In a basic air-conditioning circuit there are two _____ switches in order to protect the compressor from extremes.

Pressure

The amount of capacitance needed can be determined by connecting a(n) _______, ammeter, and voltmeter to the circuit.

Wattmeter

The _______ current is determined by the manufacturer of the hermetic refrigerant motor compressor by testing at rated refrigerant pressure, temperature conditions, and voltage.

Rated Load

A(n) ______ converts high-voltage ac into high-voltage dc.

Rectifier

A pure ________ element causes the voltage and current to be in-phase with each other

Resistive

______________________diagrams show components in their electrical sequence without regard for physical location.

Schematic

A magnetic contactor or relay is basically an electrical __________ that closes a set of contacts when the coil is energized.

Solenoid

The cooling system for the drugstore and bakery in the chapter example is a ________ system with the compressor and condenser located on the ground adjacent to the building and the evaporator located in an air-handling unit in the basement.

Split

Most dual-voltage single-phase motors will be of the _______ type, which contains both run and starting windings

Split-Phase

When a two-phase, three-wire system is used, the size of the neutral conductor must be increased by _______.

Square root of two

The _____ control circuit is often referred to as the basic circuit.

Start-Stop push button

Direct-current compound motors contain a rotating armature and a(n) _________ field.

Stationary

The hermetic compressor consists of a motor-compressor completely sealed in a gastight, ____ casing.

Steel

The speed of the rotating magnetic field of a polyphase ac motor is called ________ speed.

Synchronous

__________ motors are often made to have a leading power factor by over-excitation of the rotor current.

Synchronous

The _____ is a rotating electrical machine that has no electrical or mechanical loads connected to it.

Synchronous Condenser

The _______ operates like an electric check valve; it permits the current to flow through it in only one direction.

The Diode

Whenever the specific area is cooled to the desired temperature, a(n) ________ opens the control circuit to the motor controller and the air movement stops until the area again requires cooling.

Thermostat

SCRs and GTOs are ______ and have the ability to handle a greater amount of current than transistors.

Thyristors

The force acting at the rim of the rotor multiplied by the radius from the center of the rotor is called the ________.

Torque

An induction motor is much like a(n) ________, except that the secondary winding and core are mounted on a shaft set in bearings.

Transformer

In the precipitator, wires made of which metal give the particles a positive charge?

Tungsten

Overload protection of the internal components is covered in the _______ Standards.

UL

The step-down transformers, metering, and switching equipment necessary to supply the low voltage loads to the customer are housed in a _______.

Unit substation

The exhaust blower unit consists of a three-horsepower, three-phase, 208-volt motor driving a propeller-type fanthrough a(n) ________ drive.

V-Belt

The conductors of a single phase are not permitted to be run in metallic conduit because _________ currents will be induced

eddy

An alternative to grounding the secondary is to let it _________; that is, the secondary remains ungrounded.

float

Rate reductions are made by the power company when the metering measurements are taken on the __________ side of the transformer.

high voltage

The decimal impedance in a transformer is found by determining the ratio of the variable source voltage as compared to the rated voltage of the _____ winding.

high voltage

A device called a _______ provides a reliable method of terminating a high-voltage cable

pothead

The ______ of a transformer is the winding that is connected to a voltage source.

primary

If conductors are to be used in a location with a higher ambient temperature, the ampacity of the conductor must be _______

reduced


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