Motor Control: Lesson 8 - Special Control Components

Question 1

A ______ relay is a relay that not only maintains its contacts in the last position without a continuously energized coil, but also with a mechanical mechanism or remnant magnetism until it resets electrically.

a. frequency
b. latching
c. sequencing

Answer 1

b. latching

Question 2

______ latching relays have a latch coil and an unlatch coil.

a. Impulse
b. Magnetic
c. Mechanical

Answer 2

c. Mechanical

Question 3

When the latch coil of a(n) ______ latching relay is energized, the contacts change to their activated state. At the same time, a mechanical mechanism engages and holds the contacts in this state even after the latch coil is de-energized. When the unlatch coil is energized, it trips the mechanical mechanism, allowing the contacts to return to their normal state.

a. Impulse
b. Magnetic
c. Mechanical

Answer 3

c. Mechanical

Question 4

______ type latching relays have a single coil that operates a cam mechanism to change the state of the contacts each time the coil is energized (pulsed) for a minimum of 50 milliseconds.

a. Impulse
b. Magnetic
c. Mechanical

Answer 4

a. Impulse

Question 5

The coils of mechanically latching relays are rated for continuous operation.

True or False

Answer 5

False

Question 6

______ have contacts that prevent continuous power from being applied to the coil after it has been energized.

a. Coil clearing contacts
b. Holding contacts
c. Overload contacts

Answer 6

a. Coil clearing contacts

Question 7

______ latching relays use residual magnetic force to hold the contacts in position after the coil is de-energized.

a. Impulse
b. Magnetic
c. Mechanical

Answer 7

b. Magnetic

Question 8

______ latching relays have either single or dual coils.

a. Impulse
b. Magnetic
c. Mechanical

Answer 8

b. Magnetic

Question 9

In a(n) ______ latching relay with a single coil, the coil is pulsed with voltage at one polarity, and the solenoid plunger pulls in and is held in place by residual magnetism in the coil’s core. When the coil is pulsed with voltage at the opposite polarity, the residual magnetism is canceled and the armature is released.

a. impulse
b. magnetic
c. mechanical

Answer 9

b. magnetic

Question 10

A single coil magnetic latching relay can be used with an AC control voltage.

True or False

Answer 10

True

Question 11

______ relays are solid-state devices that simultaneously monitor each phase of a 3-phase circuit for various failures.

a. Frequency
b. Phase sequence
c. Voltage sensing

Answer 11

b. Phase sequence

Question 12

Loss of a phase, overvoltage, undervoltage, and out of sequence (phase rotation) are conditions that can be detected by ______ sequence relays.

a. frequency
b. phase
c. voltage sensing

Answer 12

b. phase

Question 13

______ relays are used in special applications where the load usage requires equal run time between two loads.

a. Alternating
b. Motor driven
c. Pump sequencer

Answer 13

a. Alternating

Question 14

A ______ relay is a solid-state device that monitors a single-phase voltage and will change output contact status when a deviation from nominal frequency is detected.

a. frequency
b. phase sequence
c. voltage sensing

Answer 14

a. frequency

Question 15

______ are electronic devices that monitor an AC or DC voltage and provide an output if that voltage is out of specification.

a. Frequency relays
b. Phase sequence relays
c. Voltage sensors

Answer 15

c. Voltage sensors

Question 16

______ refers to a predetermined step-by-step process that accomplishes a specific task.

a. Frequency
b. Sensing
c. Sequencing

Answer 16

c. Sequencing

Question 17

______ devices include pump sequencers or alternators and motor-driven sequence switches.

a. Frequency
b. Sensing
c. Sequencing

Answer 17

c. Sequencing

Question 18

The contacts of an alternating relay change state each time the initiating circuit is closed or energized.

True or False

Answer 18

False

Question 19

The control knob on many washing machines is a common example of a ______ sequencing switch.

a. alternating
b. motor driven
c. pump

Answer 19

b. motor driven

Question 20

______ counters use shaft rotations to increment or decrement numerical wheels to display an accumulated count.

a. Electronic
b. Mechanical

Answer 20

b. Mechanical

Question 21

______ counters have a numerical readout and are programmed to count up, count down, or count up and down depending on application.

a. Electronic
b. Mechanical

Answer 21

a. Electronic

Question 22

Add a phase sequence relay (PSR) contact and filler line into the three-wire control circuit.

Answer 22

Question 23

Add a phase sequence relay (PSR) contact and filler line into the three-wire control circuit.

True or False

Answer 23

True

Question 24

______ counters accumulate input pulses from two inputs and provide an output after the preset count value is reached, one input adds counts and one input subtracts counts from the accumulated total.

a. Mechanical
b. Up
c. Up/down

Answer 24

c. Up/down