Industrial Control > Midterm Controls > Flashcards

Midterm Controls Flashcards

(86 cards)

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1
Q

To reverse the rotation of a single phase motor, you must:

A

Interchange start winding (or run winding, but not both)

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2
Q

When a motor is being inched its connected to:

A

A reduced voltage

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3
Q

When a motor is being jogged, it’s connected to:

A

Full line voltage

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4
Q

A type of device used to detect flow within a pipe

A

Flow switch

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5
Q

A type of device used to monitor flow rate within a pipe

A

Flow sensor

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6
Q

A motor starter that provides overcurrent protection, overload protection, and a disconnecting means is called a:

A

Combination starter

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7
Q

2 basic types of overload relays are:

A

Thermal and magnetic

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8
Q

A float switch that is used to control a motor directly must be rated to carry:

A

FLA

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9
Q

When Installing/replacing plug-in relays, the electrician should pay close attention to:

A

The relays coil voltage

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10
Q

A method of preventing the coils of a reversing starter from energizing simultaneously is known as:

A

Interlocking

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11
Q

What are the two main parts of a solenoid:

A

Coil and plunger

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12
Q

Multiple stop buttons used to control a magnetic motor starter are placed in:

A

Series

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13
Q

Multiple start buttons used to control a magnetic motor starter are placed in:

A

Parallel

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14
Q

Two wire control provides:

A

Low voltage release

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15
Q

Three wire control provides:

A

Low voltage protection

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16
Q

The contacts of a motor starter that carry the FLA of the motor are called:

A

Pole or Line or Load contacts

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17
Q

A Thermopile exists when:

A

Two or more thermocouples are connected in series

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18
Q

Copper is used to provide good Thermal contact in what device?

A

RTD Probe

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19
Q

A device that works on the change of resistance with a change in heat:

A

RTD - resistance temperature detector

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20
Q

Thermistors exhibit:

A

Rapid change of resistance with a change in temp

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21
Q

Which relay is a length of resistive wire connected in series with the motor to sense motor current?

A

Hot wire relay

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22
Q

A device that employs the heating of two dissimilar metals is called a:

A

Thermocouple

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23
Q

With a spiral bi-metal strip, if a calibrated scale is placed behind the pointer attached to the centre of the spiral, it becomes a:

A

Thermometer

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24
Q

Two dissimilar metals bonded together have:

A

Different expansion rates

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25
What type of wire is an RTD is made of:
Platinum wire
26
The most common heat sensing device used in room Thermostats is:
Bi-metal strip
27
A long bi-metal strip is desirable because it:
Exhibits a greater movement with change in heat
28
Which proximity dectectors do not depend on metal to operate?
Capacitive Prox. Detectors
29
T or F, proximity detectors are basically just metal detectors
True
30
T or F, Sensors should be mounted as close to other metals as possible?
False
31
Most ultrasonic detectors have a wide range of adjustable:
Sensing distance
32
Ultrasonic detectors admit a:
High frequency sound
33
Most capacitive proximity detectors have a range of approximately:
25mm
34
A proximity detector that can detect non-metallic objects usually operates on a change in:
Capacitance
35
With proximity detectors, sensors should be mounted:
As far away from each other as possible
36
With an all-metal detector, a ferrous metal can be sensed at:
3 times the distance of a non-ferrous metal
37
All metal detectors operate at:
Radio Frequencies
38
Proximity detectors are basically:
Metal detectors
39
Photodetectors that have both the transmitter and the receiver units mounted in the same housing, depend on a ______ for operation.
Reflector
40
Photodetective devices emit _____ when in the presence of light.
Electrons
41
T or F, when the CAD cell is in the presence of light, it's resistance is high.
False
42
T or F, Photodetectors can be used to sense the presence or absence of almost any object.
True
43
What are the 3 categories of photo-operated devices:
1. Photo-voltaic 2. Photo-emissive 3. Photo-conductive
44
The life span of a photodectectors operation is:
Millions of times without damage or wear
45
To allow or stop current to flow, a photoconductive device changes its...
Resistance with light
46
Photodectectors detect:
Light
47
The greatest advantage of a photo-emissive device over other photo dectectors is its:
High speed switching
48
A photo-emissive device emits:
Electrons when in the presence of light
49
If neither side of a control transformer is grounded, this is generally referred to as a _____ system
Floating
50
The 120v secondary control transformer is usually bonded to ground with terminal ______.
X2
51
What terminal type do control transformers have connected to the primary and secondary leads.
Screw terminals
52
Magnetic control systems often operate on what voltage?
120V
53
Most industrial motors operate on voltages that range from:
208V - 600V
54
When do Omron eleven pin timers change state?
When the preset time has elapsed
55
Off-delay pneumatic timer contacts change state on:
Energization of the coil
56
Typically, 8-pin electronic timers are:
On-delay
57
Timers that operate by restricting the flow of air through an orifice to rubber bellows or diaphragm are:
Pneumatic
58
Programmable controllers contain _________ electronic timers.
Internal
59
Periodically, how do pulse timers operate
Continually turn on and off at regular intervals
60
What determines the full range of time for a clock timer
Gear ratio
61
T or F, pneumatic timers are limited to either normally open or normally closed contacts
False
62
A N.O.T.C contact must be connected to an _______ relay when it is to be time delayed when closing.
On-delay
63
In solenoid valves, digital means that the valve has only ______ states of operation
Two
64
T or F, Two-way solenoid valves may be normally open or normally closed
True
65
4 way solenoid valves are generally used to control air supply to:
Double acting cylinders
66
Two way solenoids usually are used to control the flow of:
Liquids or Gases
67
If the outlet side of a two-way solenoid valve is connected to the pressure lines, this could cause the valve to:
Leak, not function properly, or not seal properly
68
In a generator, when no-load is equal to full-load voltage, it's referred to as _____ compounded
Flat compounded
69
In a generator, when full-load voltage is greater than no-load voltage, it's referred to as _____compounded
Over compounded
70
In a generator, when the series field is too weak, the generator becomes _____compounded
Under compounded
71
When referring to armatures windings: Lap-wound: windings in ______ Wave-wound: windings in _____ Frog-leg-wound: windings in ___
Parallel Series Combination of both
72
Two factors that determine amount of torque produced by a DC motor?
1. Strength of the magnetic field of the pole pieces 2. Strength of magnetic field of the armature
73
Counter-EMF is:
The opposite polarity voltage provided in the produced in a motor that increases as the motor runs, reducing the current
74
Shunt motor characteristics:
-Good speed regulation - Constant speed motor - Speed does however decrease slightly with an increase in load
75
Series Motor Characteristics
-Not a constant speed motor - Torque and speed inversely proportional - Ability to develop extremely high starting torque
76
Compounded motor characteristics:
- Constant speed - Great torque - Can be long shunt and short shunt
77
How to reverse a motor:
Switching EITHER the field connections, or the armature connections, but not both
78
Single phase Shaded pole motor: hp, torque rating, rotor, uses
- Fractional hp - Lowest starting and running torque - Squirrel cage rotor - small fans, toys, appliances,etc
79
Universal single phase motor: hp, torque, rotor, uses
- Fractional to 1hp - high starting torque - Armature type rotor - power tools, drills, routers, appliances, etc
80
List the 4 types of split phase induction motors:
1. Resistant start - Induction run 2. Capacitor start - Induction run 3. Permanent split capacitor 4. Capacitor start - Capacitor run
81
What rotor type do split phase motors have?
Squirrel cage rotor assembly
82
Rank the 4 split-phase induction motors, worst to best in order of Hp
Worst: - Res. start ind. run - Cap. Start ind. Run - Permanent split cap. Best: - Cap start cap run
83
List the two broad categories of 3 phase alternators
- Rotating armature alternator - Rotating field alternators
84
3 phase Squirrel cage induction motor: hp, torque, rotor, uses
- Hp Fractional to 500 - Torque is 100% to 275% full load torque - Squirrel cage rotor - used for fans, blowers, pumps, etc.
85
3 phase wound rotor motor: hp, torque, rotor, uses
- Hp Fractional to over 500 - excellent starting and running torque - And excellent speed regulation - wound rotor assembly - Used for cranes, hoist, large compressors,
86
3 phase synchronous motor hp, torque, rotor, uses
- Hp Fractional to over 5000 - 3 single phase insulated windings spaced 120° apart - salient pole, or cylindrical pole rotor - used for power factor correction, voltage regulation, precise constant speed or slow speed motors
Industrial Control
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