Deck 18: Application of Motors

Question 1

The motor that should be used in a potentially wet area is a(n) ____ motor.

A) enclosed
B) drip proof
C) explosion proof
D) open

Answer 1

B

Question 2

The width of a drive belt is classified as ____.

A) large or small
B) narrow or wide
C) A or B
D) 1 or 2

Answer 2

C

Question 3

The voltage tolerance of a standard electric motor is ____.

A) +5% -10%
B) +10% -5%
C) +10% -10%
D) +15% -15%

Answer 3

C

Question 4

Regardless of the type of motor or application, the motor bearings require yearly lubrication.

Question 5

If the voltage supplied to the motor is well below the motor rated voltage, the current draw will be ____ it should be.

A) lower than
B) the same as
C) higher than
D) in reverse polarity than

Question 6

There is a definite relationship between the speed of the motor and the speed of the blower.

Question 7

The delta transformer has been popular in some locations in the past.

Question 8

A direct-drive motor is usually connected to a load with a ____.

A) cradle mount
B) rigid base mount
C) pulley
D) coupling

Question 9

A sleeve bearing would typically be used in a motor that operates with a ____.

A) light load and where noise is a factor
B) heavy load and where noise is a factor
C) heavy load in a dirty atmosphere
D) heavy load in a moist atmosphere

Question 10

Grounding straps are required on resilient mounted motors to ____.

A) prevent rotation of the motor in the mount
B) help reduce motor vibration transfer to the object on which the motor is mounted
C) ground the motor in case of winding failure
D) act as the position for locating the motor leads

Question 11

Why are explosion-proof motors not normally used on standard equipment?

A) They are too large.
B) They are too noisy.
C) They are too expensive.
D) They cannot be replaced.

Question 12

A motor can burn out if the supply voltage is either too high or too low.

Question 13

The locked-rotor amperage is normally ____ times as great as the run-load amperage.

A) two
B) three
C) five
D) ten

Question 14

The alignment of a motor and the driven mechanism must be done at room temperature and ____.

A) after heating with a torch
B) at operating temperature
C) after running for one minute
D) again after several days of operation

Question 15

When oiling a permanently lubricated motor, a 20-weight, non-detergent motor oil should be used.

Question 16

When referring to motors, to what does the "insulation class" relate?

A) the noise level of the motor
B) the type of base on which the motor is mounted
C) the normal operating temperature of the motor
D) both a and b

Question 17

A drip-proof motor is designed to prevent any lubricating oil from leaving any of the bearings.

Question 18

Which of the following voltages are not safe for a 208-V motor to operate?

A) 170 volts
B) 220 volts
C) 238 volts
D) both a and c

Question 19

One method a technician can employ to check a motor is to take amperage readings of a motor (both on start-up and after start-up) and compare them to the motor's nameplate.

Question 20

A slotted screw at the bottom of the bearing housing is called a ____.

A) drain plug
B) purge screw
C) relief plug
D) retaining screw

Question 21

Explain the difference between a "rigid" mount and a "resilient" rubber motor mount.

Question 22

If the applied voltage is too high, the motor may develop local hot spots within its windings, but it will not always experience  ____________________.

Question 23

Explain how a technician can verify that a motor is operating within nameplate parameters.

Question 24

Whenever possible, when changing a motor, the _________________________ should be obtained.

Question 25

The vertical condenser fan is trying to fly downward into the unit to push air out the top, which puts a real load on the end of the bearing, called the ____________________ surface.

Question 26

In order to be electrically safe, a motor that is set in a "resilient" mount, must have a(n) ____________________.

Question 27

The device that transfers the motor's energy to the driven component is called the _________________________.

Question 28

When servicing and lubricating a motor, why must a technician use the proper oil?

Question 29

What is the major advantage of a ball bearing motor over the sleeve bearing motor?

Question 30

Explain the locked-rotor amperage (LRA).

Question 31

Name four basic methods for mounting motors.

Question 32

A belt-driven blower assembly that has a resilient mounting requires a grounding strap. Why?

Question 33

The alternating current frequency supplied by the power companies in the United States is ____________________ hertz.