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Unit 19 > Unit 19 Quiz > Flashcards

Unit 19 Quiz Flashcards

1
Q

Reserve a capacity of a motor.

A

Motor service factor

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2
Q

May be used in place of the bimetal.

A

Solder pot

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3
Q

Not affected by ambient temperatures and can be located in hot areas.

A

Magnetic overload protection.

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4
Q

Has moveable and stationary contacts and can be rebuilt.

A

Contactor

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5
Q

Used to switch on/off larger contacts and starters.

A

Pilot duty relay

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6
Q

Throw away device because parts are not available for rebuilding it.

A

Relay

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7
Q

Overload protection located near or imbedded in the motor windings.

A

Inherent motor protection

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8
Q

Designed to keep the motor from restarting.

A

Manual reset

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9
Q

True or false: All bimetal elements are designed with snap action to avoid excessive arcing.

A

True

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10
Q

True or false: Magnetic overload devices are attached to the motor starter.

A

False

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11
Q

True or false: Overload protection is divided into inherent and external protection.

A

True

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12
Q

True or false: Resistance in the surface of the contact may cause the contacts to heat up and loss of spring tension.

A

True

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13
Q

True or false: In some instances, motor starter protection can indicate a motor problem better than the motor winding thermostat protection.

A

True

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14
Q

True or false: Voltage drop across contacts indicates a bad power source.

A

False

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15
Q

True or false: Silver cadmium oxide contacts are used in relays that are used for heavier duty motor switching relays.

A

True

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16
Q

True or false: A set of contacts are closed when the relay is energized. These contacts are classified as normally closed.

A

False

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17
Q

True or false: Fuses are used as motor protectors.

A

False

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18
Q

True or false: Bimetal and solder pot overload devices are thermally operated.

A

True

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19
Q

True or false: A sure sign of contact failure is discoloration on the contact surfaces.

A

True

20
Q

The contactor is a _____ with electrical contacts.

A

Magnetic coil

21
Q

What is the difference between a relay and a potential relay?

A

*The amount of current each can handle.
*Potential relay utilize a capacitor (BEMF is utilized)

22
Q

_______ contacts are rated at lower amperages than the main contacts.

A

Auxiliary

23
Q

Relays are designed to control loads that draw less than _____ amps of electric current.

A

20

24
Q

What is the difference between a starter and a contactor?

A

Starters has built in overload

25
Q

Using your meter, how can you tell a set of contacts are going bad?

A

Low voltage, if you use resistance, “O” resistance is good, 0.5 = starting to go bad
1.0= bad

26
Q

How are line and load terminals distinguished on a contactor or motor starter?

A

T= Terminal
L= Line
(There will be a diagram or letters with numbers on the component).

27
Q

The moving armature in a contactor is actuated by ______.

A

The solenoid coil

28
Q

A common practice in condensing units is to use a contactor with only one set of contacts opening only one side of the power to the unit. This is to ______.

A

Provide off-cycle heat to the compressor

29
Q

When a contactor’s coil is energized, how much resistance should be measured between terminals L1 and terminal T1?

A

0 ohms

30
Q

An inherent motor protector is a ____.

A

Thermally activated device in the motor winding.

31
Q

The service factor of an electric motor is determined by ______.

A

Motor’s reserve capacity

32
Q

Standards for motor overload protection are set by the _____.

A

National Electrical Code (NEC)

33
Q

A solder pot is part of a ______.

A

Resettable circuit breaker

34
Q

If a normally operating motor draws 75 amps on startup, it will most likely draw ______ amps when running.

A

15 FLA

75 LRA/5= 15FLA

35
Q

Use the diagram of the relay below to answer questions 35-37.

What terminals are the NO contacts?

A

2 &4

36
Q

What terminals are the NC contacts?

A

4 & 5

37
Q

What are terminals 1 & 3 used for?

A

Coil

38
Q

Draw the electrical symbol for a DPST contact configuration.

A
39
Q

Extra Credit:
1. Draw the electrical symbol for a normally closed contact.

A
40
Q

Extra Credit:

How many poles and how many throws. (See contactors at front desk when turning in your paper).

  1. ____ poles ______ throws
A

2 & 1

41
Q

Extra Credit:

How many poles and how many throws. (See contactors at front desk when turning in your paper).

  1. _____ poles _____ throws
A

1 & 1

42
Q

Extra Credit:

How many poles and how many throws. (See contactors at front desk when turning in your paper).

  1. _____ poles _____ throws
A

3 & 1

43
Q

Is the relay good or bad? (See relay at front desk when turning in your paper)

A

Bad

44
Q

Extra Credit:
6. Multiple thermocouples wired in series are called a ________.

A

Thermopile

45
Q

Extra Credit:
7. Technician “A” says that if you take a voltage reading from terminal L1 to terminal T1 on a contactor whose coil is energized, you should read zero volts. Technician “B” says that contactors can only have normally open contacts. Which of the following statements is correct?

A

Technician “A” is correct. Technician “B” is incorrect.

Unit 19 (2 decks)

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