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Term 1: Electrical Cont'd > Miscellaneous > Flashcards

Miscellaneous Flashcards

1
Q

Wire colour coding for 3 phase in Canada?

A

Red, Black, Blue/White

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2
Q

Outside the magnet, lines of force travel?

A

North to South

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3
Q

Inside the magnet, lines of force travel?

A

South to North

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4
Q

Another name for magnetic lines of force?

A

magnetic flux

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5
Q

Magnetic lines of force never cross. True or False?

A

True

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6
Q

Magnetic lines of force start at the North Pole and end at the South Pole. True or False?

A

False

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7
Q

What is Impedance?

A

Opposition to AC current flow

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8
Q

what determines voltage rating of a conductor?

A

Insulation of the conductor

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9
Q

As the current in a conductor is increased, what happens to the magnetic lines of force surrounding the conductor?

A

More lines of flux are formed and forced outward.

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10
Q

As the current in a conductor is decreased, what happens to the magnetic lines of force surrounding the conductor?

A

Lines of force collapse inwards

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11
Q

Any material that will readily release electrons is called

A

conductor

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12
Q

Best semi-conductor?

A

Silicon

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13
Q

A conductor has ____ or less valence electrons while an insulator has ___ or more

A

3 or less

5 or more

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14
Q

Semi-conductor has how many electrons in its valence shell?

A

4

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15
Q

Using the left-hand rule for coils, the thumb points in the direction of

A

flux lines or North Pole of coil

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16
Q

List four things that affect the strength of an electromagnetic coil.

A

Spacing between coil
Number of turns in coil
Magnitude or current flow
Type of core material

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17
Q

Materials that act in a similar way to iron in a magnetic field are referred to as _____________ materials

A

ferromagnetic

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18
Q

What is the most practical way of varying the strength of an electromagnet?

  • What device connected in series is used to do this?
A

vary current though the coil

  • Rheostat
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19
Q

The magnetic flux in a circuit is directly proportional to the ________________and inversely proportional to the of_______________ the magnetic circuit.

A

Magnemotive force

Reluctance

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20
Q

Opposition to the formation of flux lines in a magnetic circuit is called

A

Reluctance

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21
Q

The spreading out of the flux lines in an air gap is referred to as

A

Fringing

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22
Q

As the reluctance of a magnetic circuit is increased, the flux density of the circuit is

A

decreased

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23
Q

If the magnetomotive force applied to a magnetic circuit is increased, the flux density of the circuit is

A

increased

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24
Q

Magnetic cores are usually constructed from materials with a high _____________ and a low ______________

A

permeability

reluctance

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25
Q

The amount of energy lost due to the constant reversals of the magnetic field in AC circuits is referred to as

A

Hysteresis

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26
Q

A _________ is a wire wound into a helical coil for the express purpose of creating a stronger magnetic field.

A

solenoid

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27
Q

What is a type of electromagnetic switch?

A

Relay

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28
Q

The electric meter on a house measures the _______ passing through it.

A

wattage

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29
Q

An electric motor is an inductive load. True or False?

A

True

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30
Q

What is NOT a factor in determining impedance in an AC circuit?

A

frequency

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31
Q

Overload protection is?

A

125%

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32
Q

Relay protection is?

A

140%

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33
Q

Overcurrent protection is?

34
Q

A _______ -_____ is commonly used on a single phase fractional horse power compressor motor to disconnect the start winding after the motor starts

A

current-relay

35
Q

Direction of rotation of a single phase induction motor is determined by;

A

direction of current flow through the start winding

36
Q

The capacitor start-capacitor run (CSCR) motor provides;

A

high starting and running torque

37
Q

Capacitors are always connected in __________ to the start winding

38
Q

On a 3-phase motor, all three legs resistance should be?

39
Q

On a single-phase motor, Resistances should be additive. True or False?

40
Q

On a single phase compressor, terminals “CSR” shall have values of?

A

S-R = Most
C-S = Middle
C-R = Least

41
Q

When checking the windings of a three phase motor;

A

All three windings shall read the same resistance

42
Q

When testing the windings of a single phase motor, which terminals show the lowest resistance?

A

Common to run

43
Q

O/L and infinity readings are the same. True or False?

44
Q

If one winding shows significantly lower resistance compared to the others, it may indicate a short circuit. True or False?

45
Q

Relays are generally used to control inductive loads up to ______ amps.

46
Q

Contactors are rated according to the maximum amperage through the;

47
Q

when testing a motor with an ohmmeter, the run winding shows 1,000 ohms to the motor frame. This indicates;

A

It is grounded

48
Q

When the temperature of a negative temperature coefficient (NTC) thermistor increases, its resistance will;

49
Q

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

50
Q

Capacitance measures a capacitor’s ability to ____.

A

storage a charge

51
Q

When a capacitor is used in an ac circuit, the current _____ voltage by ____ degrees in a pure capacitive circuit.

52
Q

Current lags voltage by 90° in a pure inductive circuit. True or False

53
Q

A start capacitor will heat up during normal use. T or F?

54
Q

Capacitors can be charged with either dc or ac. True or False?

55
Q

As capacitance increases, resistance increases. T or F?

56
Q

Capacitors are charged and discharged every half cycle. T or F?

57
Q

An open capacitor will be displayed as a value in the picofarad range in most multimeters in capacitor mode.

58
Q

A faulty capacitor can be replaced with a capacitor that has a lower voltage rating. T or F?

59
Q

Voltage rating for replacement capacitor must be equal to or higher than OEM. True or False?

60
Q

Capacitors with different capacity values that share one common plate

A

Dual capacitor

61
Q

Wiring capacitors in Parallel _______ capacitance

62
Q

Wiring capacitors in Series ________ capacitance

A

cut in half

63
Q

Capacitors connected in series _______ voltage

64
Q

Capacitors connected in parallel the voltage is?

65
Q

Assists a motor in starting up

A

Start capacitor

66
Q

Energized while the motor is operating

A

Run capacitor

67
Q

Insulator between the plates in a capacitor is called a

A

Dielectric

68
Q

Type of capacitor found in circuit boards for primarily dc use are _________

69
Q

Type of capacitor used for single-phase motors _____-_________

A

non-polarized?

70
Q

Are capacitors used in three-phase motors?

71
Q

Large-value capacitor

A

Electrolytic

72
Q

Capacitors oppose the change in voltage potentials as they charge and discharge, and the opposition that results in resistance to current flow is called capacitive ________

73
Q

If off on internal overload and hot, you will read what between C-R and C-S?

A

Open/Infiniti

74
Q

Think of an AC waveform

  • Resistive circuit - voltage and current are ___ phase
  • Capacitive circuit current _____ voltage by ___degrees
  • Inductive circuit current ____ voltage by __deg
A

IN

leads, 90 deg

lags, 90 deg

75
Q

3-phase phase angle is = to ______ degrees

A

120 degrees

76
Q

Single phase peak is ___ degrees and negative peak is ____ degrees and ____ degrees at 0

A

90 degrees
270 degrees
180 degrees

77
Q

Run capacitor must be _________ or greater than voltage applied

78
Q

start capacitor must be ________ to or greater than voltage applied

A

equal to or greater

79
Q

voltage applied to start cap never exceeds ___%

80
Q

voltage applied to run capacitor never exceeds ____%

Term 1: Electrical Cont'd (7 decks)

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