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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
The amount of energy lost due to the constant reversals of the magnetic field in AC circuits is referred to as
Hysteresis
26
A _________ is a wire wound into a helical coil for the express purpose of creating a stronger magnetic field.
solenoid
27
What is a type of electromagnetic switch?
Relay
28
The electric meter on a house measures the _______ passing through it.
wattage
29
An electric motor is an inductive load. True or False?
True
30
What is NOT a factor in determining impedance in an AC circuit?
frequency
31
Overload protection is?
125%
32
Relay protection is?
140%
33
Overcurrent protection is?
225%
34
A _______ -_____ is commonly used on a single phase fractional horse power compressor motor to disconnect the start winding after the motor starts
current-relay
35
Direction of rotation of a single phase induction motor is determined by;
direction of current flow through the start winding
36
The capacitor start-capacitor run (CSCR) motor provides;
high starting and running torque
37
Capacitors are always connected in __________ to the start winding
series
38
On a 3-phase motor, all three legs resistance should be?
Equal
39
On a single-phase motor, Resistances should be additive. True or False?
True
40
On a single phase compressor, terminals "CSR" shall have values of?
S-R = Most C-S = Middle C-R = Least
41
When checking the windings of a three phase motor;
All three windings shall read the same resistance
42
When testing the windings of a single phase motor, which terminals show the lowest resistance?
Common to run
43
O/L and infinity readings are the same. True or False?
True
44
If one winding shows significantly lower resistance compared to the others, it may indicate a short circuit. True or False?
True
45
Relays are generally used to control inductive loads up to ______ amps.
25
46
Contactors are rated according to the maximum amperage through the;
contacts
47
when testing a motor with an ohmmeter, the run winding shows 1,000 ohms to the motor frame. This indicates;
It is grounded
48
When the temperature of a negative temperature coefficient (NTC) thermistor increases, its resistance will;
decrease
49
When the temperature of a positive temperature coefficient (PTC) thermistor increases, its resistance will;
increase
50
Capacitance measures a capacitor's ability to ____.
storage a charge
51
When a capacitor is used in an ac circuit, the current _____ voltage by ____ degrees in a pure capacitive circuit.
leads 90
52
Current lags voltage by 90° in a pure inductive circuit. True or False
True
53
A start capacitor will heat up during normal use. T or F?
False
54
Capacitors can be charged with either dc or ac. True or False?
True
55
As capacitance increases, resistance increases. T or F?
False
56
Capacitors are charged and discharged every half cycle. T or F?
True
57
An open capacitor will be displayed as a value in the picofarad range in most multimeters in capacitor mode.
True
58
A faulty capacitor can be replaced with a capacitor that has a lower voltage rating. T or F?
FALSE
59
Voltage rating for replacement capacitor must be equal to or higher than OEM. True or False?
True
60
Capacitors with different capacity values that share one common plate
Dual capacitor
61
Wiring capacitors in Parallel _______ capacitance
double
62
Wiring capacitors in Series ________ capacitance
cut in half
63
Capacitors connected in series _______ voltage
increase
64
Capacitors connected in parallel the voltage is?
same?
65
Assists a motor in starting up
Start capacitor
66
Energized while the motor is operating
Run capacitor
67
Insulator between the plates in a capacitor is called a
Dielectric
68
Type of capacitor found in circuit boards for primarily dc use are _________
polarized
69
Type of capacitor used for single-phase motors _____-_________
non-polarized?
70
Are capacitors used in three-phase motors?
NO
71
Large-value capacitor
Electrolytic
72
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 ________
Reactance
73
If off on internal overload and hot, you will read what between C-R and C-S?
Open/Infiniti
74
Think of an AC waveform - Resistive circuit - voltage and current are ___ phase - Capacitive circuit current _____ voltage by ___degrees - Inductive circuit current ____ voltage by __deg
IN leads, 90 deg lags, 90 deg
75
3-phase phase angle is = to ______ degrees
120 degrees
76
Single phase peak is ___ degrees and negative peak is ____ degrees and ____ degrees at 0
90 degrees 270 degrees 180 degrees
77
Run capacitor must be _________ or greater than voltage applied
GREATER
78
start capacitor must be ________ to or greater than voltage applied
equal to or greater
79
voltage applied to start cap never exceeds ___%
130%
80
voltage applied to run capacitor never exceeds ____%
110%

Term 1: Electrical Cont'd (7 decks)

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