Unit 19 Motor Controls

Question 1

The recommended repair for a defective relay is to.
A. Replace it.
B. Send it to repair shop.
C.Fix it your self.
D. None of the above.

Answer 1

A. Replace it

Question 2

The two types of relays are _______ and ______.

Answer 2

Light duty (switching) and Heavy duty (starting).

Question 3

. The two amperages that influence the choice for replacing a motor starter are _______ and ________

Answer 3

FLA and LRA

Question 4

FLA means?

Answer 4

Full load amperage

Question 5

LRA means?

Answer 5

Locked-rotor amperage

Question 6

What is the difference between a contactor and a starter?

Answer 6

A starter has overload protection devices, while a contactor doesn’t.

Question 7

True or False: A contactor can always be converted to a starter.

Answer 7

False

Question 8

What are the contact surfaces of relays contactors, and starters made of?

Answer 8

Silver. (Alloys)

Question 9

What causes an overload protection device to function?

Answer 9

An overload protection device will disconnect the motor at some current draw value that is slightly more than the FLA value so that the motor can be operated at it’s fill-load design capacity

Question 10

What is not a typical operating voltage used for relays, contactors, and motor starters?
A. 12 V
B. 24 V
C. 115 V
D. 230 V

Answer 10

12 V.

Question 11

Why is it not a good idea to file or sand the contactor contacts?

Answer 11

Filing or sanding exposes the base metals under the silver plating and speeds deterioration.

Question 12

Why is it not a good idea to use circuit protection devices to protect large motors from overload conditions?

Answer 12

The motor may be operating at an overload condition that may not cause the conductor to be overloaded.

Question 13

Under what conditions are motors allowed to operate with slightly higher-than-design loads?

Answer 13

The motor can operate above the FLA and within the service factor without harm, for a limited time.

Question 14

Under what conditions are motors allowed to operate with slightly higher-than-design loads?

Answer 14

The motor can operate above the FLA and within the service factor without harm, for a limited time

Question 15

What is the purpose of overload protection at the motor?

Answer 15

To prevent the motor from overheating and damaging itself.

Question 16

True or False A motor can be restarted immediately after it has stopped or been overloaded.

Answer 16

False

Question 17

Dirty and pitted contacts in a contactor can?

Answer 17

Cause resistance and heat.

Question 18

The moving armature in a contactor is actuated by

Answer 18

The solenoid coil.

Question 19

Crankcase heat for compressors is often controlled by using

Answer 19

Auxiliary contacts.

Question 20

The service factor of an electric motor is determined by the

Answer 20

Motors reserve capacity

Question 21

The contactor is a ______ with electrical contacts.

Answer 21

Magnetic coil.

Question 22

If the relay does not operate properly

Answer 22

It must be replaced.

Question 23

Release are designed to control loads that drawn less than ______of electric current

Answer 23

20 A

Question 24

what is considered a throwaway device because parts are not available for rebuilding it when it’s no longer functions properly

A. Relay
B. Compressor
C. Filter
D. Console

Answer 24

Relay

Question 25

the ______has a magnetic coil that opens or closes one or more sets of contacts

Answer 25

Relay

Question 26

What is typically used for starting a motor that has a

Answer 26

A general-purpose relay

Question 27

= true or false. are switching relay suitable to starting Motors

Answer 27

False

because they have more resistance in the context

Question 28

the pilot Duty relay contents are often made of a

Answer 28

find silver alloy

design for low-level current switching

Question 29

the LRA of a motor is typically five times higher than the ________ of the motor and can be as high as seven times the____

Answer 29

FLA for both

Question 30

The ______ is a large version of a relay. It can be rebuilt if it fails

Answer 30

Contactor

Question 31

The motor starter differs from a contactor because the motors ______________ built into its framework

Answer 31

Overload protection

Question 32

NEC means

Answer 32

Nation electrical code

Question 33

Bimetal and solder-pot device’s ________ operated

Answer 33

Thermally