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4th Year, Week 1 (Motor Control) > Motor Control 1 > Flashcards

Motor Control 1 Flashcards

1
Q

____ such as wind and moving water, have been used to mill grain.

A

Natural Energy Sources.

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2
Q

The source of energy that is used to drive a machine is called the ____.

A

Prime Mover.

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3
Q

Who invented the first practical AC motor?

A

Nikola Tesla

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4
Q

A ____ is a device that governs the performance of an electric motor in a predefined manner.

A

Motor Controller.

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5
Q

Define “Motor Controller”

A

Governs electric motors in a predefined manner.

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6
Q

What percentage of all electricity used in the U.S. is used to drive electric motors? (according to a ‘98 DE survey)

A

63%

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7
Q

What two organizations are the standard-setting for MC devices?

A

NEMA and IEC

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8
Q

What does ‘NEMA’ stand for?

A

National Electrical Manufacturer’s Association

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9
Q

What does ‘IEC’ stand for?

A

International Electrotechnical Commission

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10
Q

Marking and Rating are two things usually found in a ___ standard.

A

NEMA

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11
Q

T/F: NEMA only produces publications for installation professionals.

A

False

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12
Q

Which standard organization helped the development of the SI standard?

A

IEC

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13
Q

Devices built according to the ____ standard have four times longer life expectancy.

A

NEMA

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14
Q

NEMA AC motors are designed for what frequency?

A

60Hz

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15
Q

Which standard organization’s devices are application specific?

A

IEC

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16
Q

Which standard organization’s motors are rated in HP?

A

NEMA

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17
Q

T/F: It is possible for devices to meet the standards of both NEMA and the IEC.

A

True.

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18
Q

Who operates manually-activated devices?

A

A human operator.

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19
Q

Double-Break contacts have a ____ current rating of a single break of the same size.

A

Double.

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20
Q

A contact that changes state when actuated, but returns as soon as actuation is removed is called a ____.

A

Momentary Operator.

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21
Q

The two parts of a push-button are the ____ and ____.

A

Operator and Contact Block.

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22
Q

What type of push-button is used when quick actuation by the operator is needed?

A

Mushroom-Type push-button.

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23
Q

What is the most common type of selector switch?

A

A two-position selector switch with maintained contacts.

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24
Q

What type of contact is a simple toggle lightswitch?

A

A maintained contact.

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25
Q

A typical Hand-Off-Auto control operation usually has a ____ position switch and ____ contacts.

A

3, 2

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26
Q

A ____ is a three-position switch that can be used manually to change the direction of rotation of a three-phase motor.

A

Drum Switch.

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27
Q

Which of theses four types of lamps is NOT used in visual signaling devices?

I. Fluorescent
II. Incandescent
III. LED (light emitting diode)
IV. Xenon (strobe tube)

A

I. Fluorescent

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28
Q

What is a ‘cluster’ pilot light?

A

A single lamp-head with up to four separate lights for signaling.

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29
Q

What two types of visual indication are associated with ‘HAZARD’ or ‘Proceed with Caution’?

A

Flashing and Rotating Beacons.

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30
Q

Multiple indicators and signaling devices assembled in a column are called a ____.

A

‘Tower Indicator’ or a ‘Stack Light’

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31
Q

A general purpose horn audible signaling device has a maximum sound output of ____ Db.

A

108 Db.

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32
Q

Switch failures are grouped into two categories: ____ problems and ____ problems.

A

Operator and Contact.

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33
Q

____ operated devices are opened and closed by physical contact between a moving part and the actuator of the device.

A

Mechanically.

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34
Q

How does a limit switch work?

A

Physical contact with the moving part being sensed activates mechanical contacts within the device.

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35
Q

What is the most important things to consider when installing a limit switch? (Assuming the switch is chosen correctly.)

A

The rigidity and physical location of the device. It must be accessible for maintenance and replacement.

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36
Q

A correctly installed limit switch should do what two things?

A
  1. ) Permit allowed-travel

2. ) Prevent over-travel

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37
Q

A sub-class of switches that are identical, but smaller are called ____.

A

Micro-switches.

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38
Q

____ are typically used in equipment doors and panel covers to detect if doors are open or shut.

A

Miniature Switches.

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39
Q

The force applied to the actuator required to operate the switch contacts is called the ____.

A

Operating Force (OF)

40
Q

Automatically operated input devices are switches triggered by a change in a ____ parameter.

A

Process Parameter

41
Q

What are some examples of process Parameters?

A

Liquid Level, Pressure, Fluid Flow, Temperature

42
Q

What type of switch might be used around equipment like boilers, cooling lines, air compressors, and fluid pumps?

A

Flow Switches

43
Q

What type of switch is sometimes called a ‘float switch’ and is used to control the level in a tank or bin.

A

A Level Switch.

44
Q

____ switches are actuated when additional gas or liquid is added to the system.

A

Positive Pressure

45
Q

What type of switch is actuated when a gas or liquid is removed from the system?

A

Negative Pressure or ‘Vacuum’ Switch.

46
Q

What type of pressure switch measures two places and actuates based on discrepancies between the two locations?

A

A Differential Pressure Switch.

47
Q

____ is the signal range where no action occurs.

A

Dead Band or Neutral Zone

48
Q

What two types of devices utilize Neutral Zone the most?

A

Temperature and Pressure.

49
Q

Why is a Dead Band or Neutral Zone important?

A

If your pressure/temperature is right at the operating limit and is hovering there, you might have erratic operation and rapid signals. With Dead Band, there must be a significant change to actuate the device.

50
Q

Bimetallic strip, capillary tube, and direct immersion probes are examples of mechanical ____ sensing devices.

A

Temperature.

51
Q

What material is most commonly used to coat the surface of contacts?

A

Silver + Cadmium.

52
Q

What is the maximum number of contacts on a magnetic contact per NEMA?

A

8 Sets.

53
Q

What is the most common example of a definite purpose contactor?

A

A lighting contactor.

54
Q

What AC coil voltages are typical for IEC contactors?

A

24-600v

55
Q

What is the greatest disadvantage of a thermal overload relay?

A

High ambient temperatures causing issues or weakening the sensing element.

56
Q

Where in the NEC can NEMA ratings be found?

A

Chapter 1

57
Q

What configuration does “OR” logic utilize?

A

Two NO (Normally Open) Contacts

58
Q

Motor Control Drawings show all components in what state?

A

De-energized or ‘shelf state’

59
Q

Motor motion is described in what terms?

A

Clockwise/Counter-clockwise.

60
Q

What causes positive pressure switches to actuate?

A

When a gas or liquid is added to the system it monitors.

61
Q

What is an Electromechanical device?

A

A device that makes/breaks electrical connections because of physical movements/contact.

62
Q

How are control transformers rated?

A

In VA (Volt-Amperes)

63
Q

Who invented the steam engine?

A

Thomas Savery, in 1698

64
Q

When was NEMA formed, and where is its headquarters?

A

September 1, 1926. Washington D.C.

65
Q

When was the IEC formed, and where is its headquarters?

A
  1. Geneva, Switzerland.
66
Q

What is the most commonly used contactor in motor control?

A

The Push-button.

67
Q

What are the four push-button styles?

A
  1. ) Flush
  2. ) Guarded
  3. ) Extended
  4. ) Mushroom
68
Q

____ convert electrical energy into linear mechanical motion.

A

Solenoids

69
Q

A ____ is simply an electromagnetically controlled switch.

A

Relay.

70
Q

A device that switches a high power circuit using a low powered control circuit is called a(n) ____ relay.

A

Interposing.

71
Q

How many contacts can machine tool relays have?

A

8-12

72
Q

What are configurable/changeable contacts correctly called?

A

Convertible Contacts.

73
Q

A ____ is a device that keeps AC solenoids and relays from ‘chattering’.

A

Shading coil

74
Q

What control voltages do CT’s typically step down to?

A

24v or 120v

75
Q

What is inrush current?

A

A overcurrent condition when power is first applied to a magnetic/electric device.

76
Q

NEMA specifies that AC motor starters must function at voltages as low as ____ of coil voltage.

A

85%

77
Q

Where can requirements be found for when CT’s must be fuse protected?

A

In the NEC

78
Q

Per the NEC, AC circuits of what voltage and higher must be grounded?

A

50V

79
Q

Under what two conditions should voltage measurements be taken when troubleshooting XFMR’s?

A

At full load and with no load.

80
Q

What are the three basic parts of a solenoid?

A
  1. ) Body
  2. ) Actuator
  3. ) Coil
81
Q

If clips are lost and you are wiring a CT yourself, what should you do?

A

Use the wire and methods recommended in the manufacturer’s instructions.

82
Q

What are the three things to consider when sizing a CT?

A
  1. ) Inrush Current
  2. ) Steady-State Current
  3. ) Power Factor
83
Q

____ devices initiate a change in the state of contacts.

A

Pilot Devices.

84
Q

Define ‘Across-the-Line’ starting.

A

Starting without any sort of reduced voltage; at full line voltage.

85
Q

Generally, ____ are used for smaller motors and smaller loads.

A

Contactors.

86
Q

Safety Contactors are installed for the safety of ____.

A

The personnel working with MC systems.

87
Q

Arc chutes are intended to do what three things?

A

To confine, divide, and quench arcs.

88
Q

Definite purpose contactors ____ latch.

A

CAN.

89
Q

A motor starter is what two things combined?

A

A contactor and overload protection.

90
Q

When it comes to motor control;

____ protects the motor, and ____ protect the control equipment.

A

Overload and Fuses

91
Q

What are the three types of motor overloads?

A
  1. ) Thermal
  2. ) Electronic
  3. ) Magnetic
92
Q

Contacts that ‘latch’, or mechanically secure in place are called ____ contacts.

A

Seal-in

93
Q

____ relays have great flexibility to choose ranges and settings, but are costly.

A

Electronic

94
Q

What does DOE stand for?

A

Delay on Energize

95
Q

What does DODE stand for?

A

Delay on De-energize

4th Year, Week 1 (Motor Control) (2 decks)

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