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4th Year, Week 5 (Lighting Essentials 1 and Motors 3) > Motors Lvl 3 > Flashcards

Motors Lvl 3 Flashcards

1
Q

What 3 things are required for induction?

A
  1. ) Conductor
  2. ) Magnetic Field
  3. ) Relative Motion
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2
Q

T/F: Induction motors can spin at synchronous speed.

A

False. They can get close, but if the magnetic poles of the rotor and stator were synchronized, there would be no means of rotation

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3
Q

____ motors have no magnets, slip rings, or brushes.

A

Induction

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4
Q

How are synchronous motors different from induction motors?

A

In synchronous motors, the magnetic poles of the rotor and stator are locked and spin at the same speed.

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5
Q

What are the 3 types of relays for synchronous motors?

A
  1. ) PFFR
  2. ) Loss of Excitation
  3. ) Out of Step
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6
Q

What does PFFR stand for?

A

Polarized Field Frequency Relay

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7
Q

T/F: Synchronous motors are initially started as squirrel-cage motors.

A

True

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8
Q

____ resistors are used to dissipate any AC potential that builds up in the DC field winding in the rotor.

A

Discharge

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9
Q

The rotor of a(n) ____ motor produces a stationary magnetic field.

A

Synchronous

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10
Q

T/F: Any additional load added to a synchronous motor (within its rating) will not affect the speed of the motor.

A

True.

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11
Q

____ torque and maximum torque are the same value.

A

Pull out

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12
Q

____ torque and pull out torque are the same value.

A

Maximum

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13
Q

What are the 2 parts of an induction motor?

A
  1. ) Amortisseur Winding (squirrel cage)

2. ) Wound Rotor (DC field windings)

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14
Q

The bearings for high-speed rotors are located in the ____, which are bolted to the motor.

A

Endbells

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15
Q

____ motors are used to bring the rotor up to near-synchronous speed.

A

Pony

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16
Q

What happens when a synchronous motor slips out of synchronicity?

A

Protective relays shut it down before it destroys itself.

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17
Q

What does a PFFR do?

A

Simultaneously removes the discharge resistor and connects the DC field windings on startup.

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18
Q

T/F: Synchronous motors have little effect on the power factor of a facility.

A

True

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19
Q

What are the three circuits within a synchronous motor starting circuit?

A
  1. ) Power Circuit
  2. ) Control Circuit
  3. ) Exciter Circuit
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20
Q

The ____ circuit contains a discharge resistor that is a complete path for the current induced in the field windings.

A

Exciter

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21
Q

On startup, an ammeter may read up to ____% of running current.

A

700%

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22
Q

____ torque is the speed at which a squirrel cage motor starts to slow down when being overloaded.

A

Breakdown

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23
Q

The difference in angle between the stator’s magnetic poles and the rotor’s magnetic poles is called the ____.

A

Torque Angle.

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24
Q

A synchronous motor that is ran with no load just for power factor correction is called a ____.

A

Synchronous Condenser

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25
Q

____ braking is when a resistor is used to dissipate energy from a still-spinning motor by using it as a generator, and a resistor as a load.

A

Dynamic

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26
Q

____ braking is when the inertia of the still running motor is used to generate power which is used.

A

Regenerative

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27
Q

T/F: Brake solenoids for friction brakes should be connected to the motor power circuit.

A

True, this way, when the motor loses power, it is stopped when the solenoids release.

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28
Q

____ is when relays reverse motor connections to reverse rotation and the motor develops a countertourque.

A

Plugging

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29
Q

Plugging creates high ____ and heat.

A

Current

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30
Q

____ braking is the only braking method that can stop in the event of power failure.

A

Friction

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31
Q

____ braking provides an immediate stop in an emergency situation.

A

Electric

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32
Q

An ____ system prevents two sets of contacts from being connected to the same load at the same time, to prevent damage.

A

Interlock

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33
Q

What are the 3 types of interlocking?

A
  1. ) Mechanical
  2. ) Pushbutton
  3. ) Electronic
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34
Q

____ breaking causes the same amount of heat as starting at full voltage.

A

Electric

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35
Q

____ braking is the only braking style that won’t bring the motor to a complete stop.

A

Dynamic

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36
Q

____ motors have two windings, the brushes move across the windings to change the voltages.

A

Shrage

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37
Q

T/F: A separate starter is required for each speed of a consequent pole motor.

A

True

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38
Q

____ motors usually have two speeds, one being half the other.

A

Consequent Pole

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39
Q

What are the 3 logic functions when controlling a consequent-pole motor?

A
  1. ) Compelling
  2. ) Accelerating
  3. ) Decelerating
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40
Q

When you push the ‘High’ Button on ____ logic functions, it starts the motor on low before transitioning to high.

A

Accelerating

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41
Q

____ logic functions requires the operator to start the motor on low before transitioning it to high speed.

A

Compelling

42
Q

The ____ section of an adjustable speed driver controls the speed and torque by controlling voltage, frequency, and current.

A

Inverter

43
Q

The inverter section of a VFD controls what three things?

A
  1. ) Voltage
  2. ) Frequency
  3. ) Current
44
Q

What are the three parts of VFD?

A
  1. ) Converter (rectifier)
  2. ) DC bus
  3. ) Inverter
45
Q

Damage may occur to an AC motor if supply voltage is applied ___% above or below the rated nameplate voltage.

A

10%

46
Q

The frequency of the voltage used to control the motor is called the ____ frequency.

A

Fundamental

47
Q

The ____ frequency is the modulated frequency coming out of the inverter.

A

Carrier

48
Q

Drives for ____ motors are the most complex.

A

Compound-Wound

49
Q

The ____ frequency is often raised above human hearing to eliminate noise.

A

Carrier

50
Q

____ drives have greater control over speed and torque than a standard inverter drives.

A

Vector

51
Q

____ ____ inverters are the only drives that can run multiple motors at one time.

A

Variable-Voltage

52
Q

A motor hooked up in ____ will have fewer poles, and rotate faster.

A

Series

53
Q

A motor hooked up in ____ will have more poles, and rotate slower.

A

Parallel

54
Q

____ bearings have no moving parts. (other than the shaft)

A

Friction

55
Q

____ bearings have either steel balls or rods that move within the bearing.

A

Rolling-contact

56
Q

____ is the general wear of rolling contacts as metal pieces flake away the surfaces in contact, leaving a roughened surface.

A

Spalling

57
Q

____ damage is bearing damage due to axial force.

A

Thrust

58
Q

____ bearings are quieter, less expensive, have less wear, and can take heavier loads than other types of bearings.

A

Friction Bearings

59
Q

The inner and outer ____ are the the tracks that contain the cage for ball bearings.

A

Races

60
Q

____ is damage caused by chemical reactions between the lubricant and the bearings.

A

Surface Reaction

61
Q

____ is a normal condition that just comes from normal wear and oxidation.

A

Fretting Corrosion

62
Q

____ bearings can handle both axial and radial loads. Special Friction bearings also can.

A

Tapered

63
Q

____ and ____ is damage caused by electrical current flowing through a bearing.

A

Pitting and Fluting

64
Q

Cylindrical bearings are not made to handle ____ force.

A

Axial

65
Q

____ bearings bear directly on the rotating shaft.

A

Needle

66
Q

T/F: Bearings fail more often due to poor installation than bearing failure.

A

True

67
Q

The best heating method for expanding a bearing is (a) ____.

A

Hot oil bath

68
Q

T/F: Bearing installation is more difficult than removal.

A

False, It’s easier to heat and set a bearing initially than try to slip/press it off.

69
Q

____ damage is dents on any component of a bearing due to dropping/hitting/pressing.

A

Brinell

70
Q

____ close spaces between moving parts of moving and stationary components.

A

Oil Seals

71
Q

A common mistake when greasing bearings is ____.

A

Over-lubricating

72
Q

____ Gears have teeth that are NOT parallel to the shaft.

A

Helical

73
Q

____ gears have bevels and are used when two shaft axes intersect.

A

Bevel

74
Q

A(n) ____ clutch uses a magnetic field to couple a motor to a load.

A

Eddy Current

75
Q

____ gears are the most common in industry.

A

Spur

76
Q

A(n) ____ V-belt has a smaller cross section and a higher profile, giving it more friction with the sheaves.

A

Narrow

77
Q

A(n) ____ belt has teeth on it so that it cannot slip.

A

Timing

78
Q

What are the three types of sprockets?

A

A (No Hubs)
B (One Hub)
C (Two Hubs)

79
Q

A(n) ____ is a grooved wheel to hold a v-belt.

A

Sheave

80
Q

A(n) ____ is a coupling that can connect or disconnect a load while a motor is running.

A

Clutch

81
Q

What are the four different types of Soft Footing?

A
  1. ) Parallel
  2. ) Angular
  3. ) Springing
  4. ) Induced
82
Q

____ soft foot is when external forces are applied to the motor.

A

Induced

83
Q

What is the phonetic device Derek told us to remember, that helps with remembering what order to align motors in?

A

VAP HAP
(Vertical - Angular - Parallel)
(Horizontal - Angular - Parallel)

84
Q

What does MTBS stand for?

A

Machine to be shimmed.

85
Q

What does SM stand for?

A

Stationary Machine

86
Q

Why is the motor almost always the MTBS?

A

Because it’s almost always easier to move/adjust the motor than to move the machine it’s running.

87
Q

____ is when the bolt head of a mounting bolt disfigures the washer.

A

Doweling

88
Q

A(n) ____ circuit occurs when current leaves its normal current path and travels to the frame of the motor.

A

Ground Fault

89
Q

____ is the most common cause of motor failure.

A

Overloading

90
Q

____ is when one of the three-phase leads drops out and no longer delivers voltage to the motor.

A

Single-Phasing

91
Q

____ is the most extreme example of voltage imbalance.

A

Single-Phasing

92
Q

Belt deflection should equal about ___” per inch of span, the span being measured from center to center.

A

1/64”

93
Q

____ detect insulation failure on wires by measuring resistance values of the windings.

A

Megohmmeters

94
Q

____-____ starting is the most modern example of reduced voltage starting.

A

Solid-State

95
Q

____ are the fastest wearing components of a DC motor.

A

Brushes

96
Q

____ material is a medium in which an electric field is maintained with little or no outside energy supply.

A

Dielectric

97
Q

Split-Phase motors have their start winding removed by a(n) ____ as the motor accelerates.

A

Centrifugal Switch

98
Q

A dual voltage, wye connected motor has __ separate stator windings.

A

4

99
Q

Generally, a dual voltage, delta connected motor has __ separate stator windings.

A

3

100
Q

Terminals __ and __ are always the connection leads for shunt windings.

A

F1 and F2

4th Year, Week 5 (Lighting Essentials 1 and Motors 3) (2 decks)

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