Unit 20 Quiz

Question 1

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

Answer 1

Keyway

Question 2

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

Answer 2

Open Winding

Question 3

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

Answer 3

Single phasing

Question 4

Tool used to remove a pulley from a shaft.

Answer 4

Pulley puller

Question 5

Windings touch each other where the insulation is worn.

Answer 5

Winding short circuit

Question 6

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

Answer 6

Oxidation

Question 7

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

Answer 7

Megohmmeter

Question 8

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

Answer 8

High limit control

Question 9

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

Answer 9

Set screw

Question 10

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

Answer 10

Pulley alignment

Question 11

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

Answer 11

Winding to ground short circuit

Question 12

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

Answer 12

Ground/earth

Question 13

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

Answer 13

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

Question 14

What is the minimum information required for setting belt tension?

Answer 14

Belt size, drive/driven pulley diameters.

Question 15

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

Answer 15

Capacitor and start winding terminal.

Question 16

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

Answer 16

True

Question 17

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

Answer 17

False

Question 18

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.

Answer 18

False

Question 19

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

Answer 19

True

Question 20

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

Answer 20

True

Question 21

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

Answer 21

True

Question 22

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

Answer 22

True

Question 23

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

Answer 23

True

Question 24

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

Answer 24

False

Question 25

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.

Answer 25

False

Question 26

How can a technician tell if a belt is slipping?

Answer 26

Utilize a belt tension gauge

Question 27

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

Answer 27

With the starting components

Question 28

An open winding in an electric motor means ________.

Answer 28

A wire in the winding is broken.

Question 29

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.

Answer 29

Cannot identify terminals, open winding.

Question 30

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.

Answer 30

Start

Question 31

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

Answer 31

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

Question 32

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

Answer 32

angular and parallel

Question 33

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.

Answer 33

True

Question 34

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

Answer 34

Zip ties will eventually break off

Question 35

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

Answer 35

over tightened belt and belt slippage