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Hvav Vocabulary Practice > HVAC Electrical application practice > Flashcards

HVAC Electrical application practice Flashcards

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1
Q

Resistance can be calculated by

A

E divided by I

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2
Q

Any material that will readily release electron is called

A

A conductor

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3
Q

single phase motor speed is determined by the

A

Number of stator pole

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4
Q

A device used to control a motor is a

A

Relay
contactor
Line starter
All of the Above

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5
Q

The meter on a house measures the __ passing through it.

A

Wattage

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6
Q

Which of the following is the correct formula for determining wattage in an electrical circuit?

A

W= E time I

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7
Q

impedance in a circuit is the result of;

A

pure resistance
inductive reactance
capacitive reactance
all of the above

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8
Q

To change the direction of rotation of a three-phase motor;

A

change the position of any two supply wires

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9
Q

A transducer can create a signal based on a form of energy such as.

A

pleasure
heat
fluid flow
all of the above

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10
Q

what is current flow?

A

the flow of electrons in the circuit

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11
Q

when the temperature of a positive coefficient (PTC) thermistor increases, its resistance will

A

Increase

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12
Q

A solenoid valve operates on the principle of.

A

Electromagnetism

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13
Q

the synchronous speed of a four pole, 60 Hz single phase motor is

A

1800 rpm

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14
Q

which of the following statements about current is true?

A

current flow will increase when voltage increase

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15
Q

a transformer has 1000 turns of wire in the primary coil and 2000 turns in the secondary coil. if 120 volts are applied, the output voltage will be

A

240 volts

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16
Q

fuses are used to protect

A

wires

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17
Q

when checking the winding of a three-phase motor

A

all three terminals should show the same resistance

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18
Q

with a motor running a full load, voltmeter leads are placed on each side of the relay contacts. The voltmeter gives no measurable voltage. this is an indication of.

A

Good clean contact

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19
Q

in a single-phase compressor motor, which winding terminals have the most resistance?

A

run to start

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20
Q

Once horsepower is equal to __ watts?

A

746

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21
Q

What is the term used to describe the output side of a transformer?

A

Secondary side

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22
Q

Step-up transformer increase;

A

voltage

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23
Q

A capacitor opposes current flow in a circuit. This opposition is called;

A

Capacitive reactance

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24
Q

when the temperature of a negative temperature coefficient (NTC) thermistor increases. Its resistance will.

A

Decrease

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25
Q

Two 120-volt motors are wired in series, once is a 60-watt motor, the other is a 4-watt motor. the result would be.

A

Neither motor would operate normally

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26
Q

Capacitors are always connected__ to the start winding.

A

In series

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27
Q

A capacitor analyzer is designed to,

A

-read power factor percentage
-diagnose an open or shorted capacitor
-read the microfarad rating of a capacitor
all of the above

28
Q

when current flows, a _ is produced around the conductor

A

Magnetic field

29
Q

what is impedance?

A

opposition to alternating current

30
Q

three resistors are wired in series, each has a value of 300 ohms. what is the total resistance of the circuit?

A

900 ohms

31
Q

how many resistances must be placed in a 110-volt circuit in order to limit the current to 2 amps?

A

55 ohms

32
Q

what type of meter uses its own battery?

A

ohmmeter

33
Q

A 240 volt, 3 wire circuit can be split into two 120 volt circuits

A

True

34
Q

which of the following is equal to 2.1 kv?

A

2,100 volts

35
Q

the safety ground conductor is usually color coded

A

Green

36
Q

An electron has

A

A negative charge

37
Q

what is resistance?

A

opposition to current flow

38
Q

what is generally considered to be the Maximum allowable (plus or minus) supply voltage variation?

A

10%

39
Q

the terminals T1, T2, T3 are located at the _ of a contactor

A

Bottom

40
Q

in electrical wiring, a black colored wire usually indicates.

A

the hot conductor

41
Q

electricity can produce

A

heat
light
Magnetism
all of the above

42
Q

which of the following is equal to 100 milliamps?

A

0.10 amperes

43
Q

A transformer has 1000 turn of wire in the primary coil and 500 turns in the secondary coil. if 120 volts are applied, the output voltage will be

A

60 (x/120x500/1000= 60,000/1000)

44
Q

the capacitor start- capacitor run (CSCR) motor,

A

High starting torque

high running torque

45
Q

like charges will

A

repel each other

46
Q

what meter is used to bench check a motor for shorts or open Widings?

A

ohmmeter

47
Q

Amperes can be calculated by

A

E divided by R
W divided by E
The square root of W divided by R

48
Q

the symbol for current is

A

I

49
Q

when resistors are wire in a parallel

A

the voltage drop across each resistor will be the same as the applied source voltage

50
Q

contactors are rated according to the maximum amperage through the

A

contacts

51
Q

an ohmmeter should never be connected to

A

a live circuit

52
Q

the_ drawing illustrates where the components are located on the appliance.

A

pictorial

53
Q

if the conductor in an AC circuit is wound into a coil, the resulting EMF opposes the supply voltage. this opposition is called,

A

inductive reactance

54
Q

when testing a capacitor with an analog ohmmeter, the needle on the meter should,

A

Deflect towards zero then return to infinite reading

55
Q

direction of rotation of a single-phase induction motor is determined by

A

the direction of current flow through the start winding

56
Q

the thermal overload contacts on a line starter are usually _ reset.

A

manual

57
Q

to discharge a capacitor prior to ohmmeter testing

A

use a 20,000-ohm resistor to short across the terminals

58
Q

voltage can be calculated by

A

I time R

59
Q

how are fuses sized?

A

Amps

volts

60
Q

capacitors are rated in

A

Microfarad

Volts

61
Q

transformers are rated according to

A

AV at the secondary

62
Q

the total resistance of a parallel circuit will be

A

less than the smallest resistance

63
Q

relays used in the HVAC industry are generally used to control loads up to _ amps

A

25

64
Q

utility companies usually supply residential homes with a _ service

A

240v, single phase, three wire

65
Q

a parallel circuit contains an 18 ohm and a 9-ohm resistor. the total resistance equals

A

6 ohms

66
Q

in the schematic, the crankcase heater will operate

A

when the compressor is off

Hvav Vocabulary Practice (4 decks)

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