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Unit 20 > Unit 20 Quiz > Flashcards

Unit 20 Quiz Flashcards

1
Q

Made of very hard steel. Used to secure the assembly to the motor shaft.

A

Keyway

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2
Q

Broken motor winding indicated by “OL” when checked with an ohmmeter.

A

Open Winding

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3
Q

When a 3-phase motor is trying to run on two power leads.

A

Single phasing

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4
Q

Tool used to remove a pulley from a shaft.

A

Pulley puller

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5
Q

Windings touch each other where the insulation is worn.

A

Winding short circuit

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6
Q

Combining of a material with oxygen to form a different substance which results in the deterioration of the original substance. Acts as electrical resistance.

A

Oxidation

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7
Q

Used to check the condition of wire insulation and oil within a motor or compressor.

A

Megohmmeter

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8
Q

Shuts the furnace or boiler down when temperature in the furnace becomes excessive.

A

High limit control

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9
Q

Provides a better bond between the motor and whatever assembly is attached to the shaft.

A

Set screw

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10
Q

Strain on the drive mechanism shaft bearings and/or the driven shaft bearings can be prevented by doing this procedure.

A

Pulley alignment

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11
Q

Short circuit from motor winding to the frame of the motor.

A

Winding to ground short circuit

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12
Q

The proper connection between electrical installation systems via a conductor to the buried plate/rod in the earth.

A

Ground/earth

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13
Q

How should a capacitor be properly discharged according to chapter 20?

A

By shorting one terminal to the other with a 20,000 ohms, 5 watt Resistor.

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14
Q

What is the minimum information required for setting belt tension?

A

Belt size, drive/driven pulley diameters.

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15
Q

When testing a run capacitor under load, measure the amperage reading between the _________.

A

Capacitor and start winding terminal.

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16
Q

True or false: The voltage measurement should be taken at the capacitor terminals when testing a run capacitor under load.

A

True

17
Q

True or false: When megging a compressor motor, disconnect only the common and start winding terminals from the compressor motor terminals.

A

False

18
Q

True or false: A meter reading 1,000,000 ohms from one meter terminal to ground indicates that the motor has a short to ground and should not be started.

A

False

19
Q

True or false: If the run to start resistance measurement is “OL”, either the run winding or the start winding is open.

A

True

20
Q

True or false: When a connection becomes loose, oxidation of the copper wire occurs and could cause the connection to heat up.

A

True

21
Q

True or false: Connecting a polarized capacitor in the wrong orientation may damage a motor.

A

True

22
Q

True or false: Most electrical problems with an electric motor are short circuited windings, open windings and grounded windings.

A

True

23
Q

True or false: If resistance of the run winding decreases, the motor will draw too much current while it is running.

A

True

24
Q

True or false: If a condenser fan motor grounds out, it will usually keep running as the current is only going to ground.

A

False

25
Q

True or false: If a resilient mounted motor develops a short to the frame, the technician can simply cut the ground strap wire as a permanent repair.

A

False

26
Q

How can a technician tell if a belt is slipping?

A

Utilize a belt tension gauge

27
Q

If a motor hums but does not start, there is a potential problem __________.

A

With the starting components

28
Q

An open winding in an electric motor means ________.

A

A wire in the winding is broken.

29
Q

A technician needs to check a single phase compressor. He labels the three terminals A, B and C and takes resistance readings of the windings. He reads 10 ohms from A to B, OL from B to C and OL from and OL from C to A.

A

Cannot identify terminals, open winding.

30
Q

A motor has four leads out of it, two red and two black. The resistance between the red leads is 3 ohms. The resistance between the black leads is 5 ohms. The black leads are connected to the _______ winding.

A

Start

31
Q

Extra Credit:
1. Name the six styles of setscrews that may be used to hold a pulley on a shaft.

A

Dog point, Half Dog point, cup point, oval point, cone point, flat point.

32
Q

Extra Credit:
2. What are the two types of pulley misalignment?

A

angular and parallel

33
Q

Extra Credit:
3. True or false: Loose connections will appear the same as a set of dirty or burnt contacts and can be located with a multimeter.

A

True

34
Q

Extra Credit:
4. Why is it not an approved method to secure a run capacitor with a plastic zip tie?

A

Zip ties will eventually break off

35
Q

Extra credit:
5. Two common reasons for motor failure are improper pulley alignment and ________.

A

over tightened belt and belt slippage

Unit 20 (1 decks)

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