Segment 4 Final Review
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
