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Motors Class > Knowledge Base 3 > Flashcards

Knowledge Base 3 Flashcards

1
Q

T F

Pilot duty devices are normally used to switch horsepower rated loads

A

d

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2
Q

Which of the following is a primary control device

Flow Switch
Thermostat
Motor Start
Pressure Switch

A

motor starter

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3
Q

T F

A push button would normally be considered to be a pilot control devvice

A

TRUE

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4
Q

A manually operated switch is one that is controlled by ___

A

HAND

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5
Q

What do the SPDT and DPDT switches look like

A

look at the pictures

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6
Q

T F

The DC current rating of a switch would have a value of lower magnitude than the AC rating

A

TRUE

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7
Q

Identity your symbols from page 1

A

d

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8
Q

The NC push button ___ the circuit when it is pressed and returns to the ____ position when the button is released

A

OPENS

CLOSED

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9
Q

Electrical ____ are designed to protect their contents from operating environmental conditions

A

Enclosures

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10
Q

A push button may consist of one or more ____ blocks, a(n) ____ device, and a(n) _____plate

A

Contact Blocks

operator

legend

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11
Q

_____head push button operators are used for emergency stop push buttons

A

Mushroom

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12
Q

T F

A pushbutton assembly can only have one contact block

A

FASLE

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13
Q

Once actuated, ______type pushbutton operators are required to be actuated a second time to return the contacts to their normal off state.

A

Maintained

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14
Q

Emergency stop push buttons must be of the maintained contact type.

(True/False) _________

A

TRUE

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15
Q

Draw the NEMA and IEC symbols used to represent a red pilot light:

A

f

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16
Q

Push-to-test pilot lights can be energized from two separate signals of different voltage values. (True/False

A

TRUE

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17
Q

All selector switches operate with spring return to provide momentary contact operation. (True/False)

A

FASLE

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18
Q

Drum switches are only used for starting and reversing three-phase squirrel-cage motors. (True/False

A

FASLE

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19
Q

A mechanically operated switch is one that is specifically controlled by hand. (True/False

A

False

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20
Q

Limit switches are designed to be operated:

a. By the machine operator
b. When a predetermined pressure is reached
c. When a predetermined temperature is reached
d. By contact with an object

A

D

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21
Q

Identify each of the switch symbols shown in Figure 4-3:

A

f

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22
Q

The type of limit switch shown in Figure 4-4 would be classified as a

A

LEVER TYPE A

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23
Q
  1. Micro limit switches require a large amount of pressure to be applied to the operating lever in order to actuate the contacts.(True/False)
A

FALSE

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24
Q

The type of temperature switch shown in Figure 4-5 is

A

Capillary tube temperature switch

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25
Q

All temperature switches use only N.O. (normally open) contacts.

(True/False)
A

FALSE

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26
Q

The three categories of pressure switches are _____________________
pressure, _________________ pressure, and _____________________ pressure.

A

Positive pressure

Vacuum (negative pressure)

Differential pressure

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27
Q

Pressure switches open or close when a preset pressure is reached.

(True/False)

A

TRUE

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28
Q

The type of switch shown in Figure 4-6 would be classified as a

A

Float Switch

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29
Q

Sensors are devices that are used to ____________________ and ______________the presence of something

A

detect

measure

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30
Q

A proximity sensor can detect the presence an object without physical
contact. (True/False)

A

TRue

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31
Q

An inductive proximity sensor can be actuated by both conductive and
nonconductive materials. (True/False)

A

TRUE

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32
Q

Identify each component block of the inductive proximity sensor shown in Figure 4-7.

A
  1. Coil
  2. Oscillator
  3. Detector
  4. Output
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33
Q

Draw acceptable NEMA and IEC symbols used to represent an N.O. proximity switch.

A

f

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34
Q

The proximity sensor shown in Figure 4-8 would be classified as a:

A

3 wire connection

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35
Q

A proximity sensor should never normally be used to directly operate a
motor. (True/False)

A

TRUE

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36
Q

The electronic switching circuit of a sensor:

a. Has infinite resistance in the off state
b. Will allow a small amount of current to flow through it in the off state
c. Will have a small voltage drop across it in the on state
d. Both band c

A

D

37
Q

When a metal object enters the high-frequency field of an inductive proximity, it causes:

A

f

38
Q

In order to operate properly, a two-wire proximity sensor should be powered continuously. (True/False

A

True

39
Q

The area between the operating and release points of a proximity sensor is known as the______________ zone.

A

hysteresis

40
Q

The position identified on the field of the proximity sensor shown in Figure 4-9 is known as the:

A

Operating point

41
Q

A capacitive proximity sensor produces an

a. Electromagnetic sensing field
b. Electrostatic sensing field
c. Constant current sensing field
d. Constant voltage sensing field

A

Electro-Static field

42
Q

When the target enters the field of a capacitive proximity sensor, the
oscillator circuit begins oscillating. (True/False)

A

True

43
Q

Capacitive proximity sensors will sense only nonmetallic materials.

(True/False)
A

False

44
Q

Identify the two basic components of the photoelectric sensor shown in Figure 4-10.

A

A. Transmitter

B. Receiver

45
Q

Identify the type of scan technique used for each of the photoelectric sensors shown in Figure 4-11.

A

a. Retroflective Scan
b. Through Beam scan
c. diffuse scan sensor

46
Q

Which of the following scan techniques is best suited for long-range scanning?

a. Through-beam 
b. Retroreflective 
c. Polarized retroreflective 
d. Diffuse
A

Through Beam

47
Q

A_________________ retro reflective scan sensor is designed to be able to detect shiny objects.

A

TRUE

48
Q

Fiber optics can be used with through-beam, retroreflective, or diffuse scan sensors. (True/False

A

TRUE

49
Q

Fiber optic sensor systems are completely immune to all forms of electrical
interference. (True/False

A

TRUE

50
Q

Hall-effect sensors are used detect both the proximity and the_________________ of a magnetic field

A

strength

51
Q

Identify the measurement application for the Hall-effect sensing circuits shown in Figure 4-12.

A

a. Hall efect sensor for monitering current

b. Hall effect sensor used for measuring speed

52
Q

An ultrasonic sensor operates by sending high-frequency ________________
waves toward the target and measuring the ________________ it takes for
the pulses to bounce back.

A

sounds

time

53
Q

For the ultrasonic sensor shown in Figure 4-13, the sensor will generate a signal of approximately___________ mA when the tank is full and
______________ mA when the tank is empty

A

20 ma when full

4 ma when empty

54
Q

Identify each type of temperature sensor shown in figure 4-14

A
  1. Thermo couple

2.

55
Q

Which of the following temperature sensors operates on the principle that electrical resistance of metals is directly proportional to temperature?

a. IC 
b. RTD 
c. Thermocouple 
d. Thermistor
A

RTDs

56
Q

The output voltage of a thermocouple is proportional to the difference in
voltage between the _________________ junction and the _________________ junction.

A

hot junction

cold junction

57
Q

Different thermocouple types basically have the same voltage output curves. (True/False)

A

False

58
Q

Which of the following temperature sensors provides the most accurate measurement of temperature?

a. IC   
b. RTD   
c. Thermocouple   
d. Thermistor
A

RTD

59
Q

The material most often used for resistance temperature detectors is

a. Platinum   
b. Gold   
c. Copper   
d. Aluminum
A

Platinum

60
Q

As the temperature of a thermistor with a negative temperature coefficient increases, its resistance decreases. (True/False)

A

TRUE

61
Q

The operating temperature range of the IC temperature sensor is much lower than that of a thermocouple. (True/False)

A

TRUE

62
Q

A tachometer generates a voltage that is proportional to

A

rotational speed

63
Q

Identify the parts of the magnetic pickup sensor shown in Figure 4-15

A

a. magnet
b. coil
c. pole piece
d. connector

64
Q

A magnetic pickup sensor generates pulses that are counted to determine
shaft speed. (True/False)

A

TRUE

65
Q

An encoder sensor is used to convert linear or rotary motion into a binary _________________ signal

A

digital

66
Q

Encoder sensors are used in applications such as robotic control where
__________________ have to be accurately determined.

A

positions

67
Q

Identify each type of flowmeter shown in Figure 4-16.

A

Left: Turbine flowmeter
Right: Target Type flow meter

68
Q

The usual approach taken to measure fluid flow is to convert the __________ energy that the fluid has into some other measurable form.

A

kenetic

69
Q

Which of the flowmeters operates by measuring the changes of induced voltage of a conductive fluid?

a. Magnetic   
b. Target   
c. Turbine   
d. Differential pressure
A

Magnetic

70
Q

An actuator is any device that converts an electrical signal into
___________________________________________ .

A

mechanical movement

71
Q

The contacts of an electromechanical relay are switched by energizing and
de-energizing a(n) ________________________

A

coil

72
Q

The normally closed contact of a relay is closed any time the coil is energized. (True/False) _________

A

False

73
Q

A solenoid is made up of coil with a movable ______________________

A

plunger

74
Q

Which type of solenoid is shown in Figure 4-17

A

Rotary

75
Q

An AC solenoid rated for 120-V alternating current, if connected to a 120- V direct current source, would draw a much lower than normal current.

(True/False)
A

FALSE

76
Q

If a DC solenoid sticks in the open position, a burnout of the coil is likely.

(True/False)
A

FALSE

77
Q

In AC solenoids, coil current decreases as the plunger moves toward the

seated position. (True/False)
A

f

78
Q

A solenoid valve is a combination of a solenoid coil operator and:

a. Contacts 
b. Sensor 
c. Transmitter 
d. Valve
A

f

79
Q

When a solenoid valve is electrically energized it can be designed to

a. Open the flow of media 
b. Shut off the flow of media 
c. Direct the flow of media 
d. All of these
A

D

80
Q

Stepper motors rotate continuously when voltage is applied to their
terminals. (True/False)

A

TRUE

81
Q

For a DC stepper motor, the amount of rotation is directly proportional to

the \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ of pulses and the speed to the 

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ of the pulses.
A

number

frequencey

82
Q

Generally, stepper motors are rated for more than 1 hp and are used to operate very heavy loads. (True/False

A

False

83
Q

Stepper motor systems can provide precise position control of movement
without the use of a feedback signal. (True/False)

A

TRUE

84
Q

Stepper motor systems can provide precise position control of movement

without the use of a feedback signal. (True/False)
A

TRUE

85
Q

An open-loop motor control system is one that is operated:

a. Without a feedback signal 
b. With a feedback signal 
c. Without a reference signal 
d. With a reference signal
A

A

86
Q

All servo motors operate using a closed-loop control system.

(True/Fa1se)

A

TRUE

87
Q

Identify all blocks for the servo motor control system shown in Figure 4-18

A

A. Servo Motor
B. Controller
C. Servo Amplifier
D. Feedback device

88
Q

Brushless DC motors are mechanically commutated.

A

False

Motors Class (2 decks)

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