Mechanics (Motors Quiz)

Question 1

What are the 2 basic types of motors?

Answer 1

AC and DC

Question 2

What are the 2 basic types of AC motors?

Answer 2

Single Phase (Single Ø)
3 Phase (3 Ø)

Question 3

What are the common AC voltages for Single Phase?

Answer 3

110VAC, 115VAC, 120VAC, 220VAC, 230VAC, and 240VAC

Question 4

What are the common AC voltages for 3 Phase?

Answer 4

208VAC, 220VAC, 230VAC, 240VAC, and 480VAC

Question 5

What increment (of an inch) are frames measured in (base to shaft center) if the tag has 2 numbers?

Answer 5

1/16”

Question 6

What increment (of an inch) are frames measured in (base to shaft center) if the tag has 3 numbers?

Answer 6

1/4”

Question 7

On a 3 number tag, what does the 3rd number refer to?

Answer 7

Bolt pattern

Question 8

What are the shaft and mounting types listed on the motor’s tag?

Answer 8

T, TC, TS, C, JM, and JP

T - Long Shaft
TC - C Face with Long Shaft
TS - Short Shaft
C - C Face
JM - Closed Coupled Pump
JP - Closed Coupled Pump

Question 9

What are the common reasons AC motors overheat?

Answer 9

•High/Lower Voltage
•Frequent/Repeated Starts
•High Ambient Temperature
•Clogged/Dirty Vent holes/cooling fins
•Voltage imbalance in 3 phase motors

Question 10

What is the same as the motors insulation rating?

Answer 10

Motor class

Question 11

How are motors classed?

Answer 11

Letter (A,B,F,H) indicating how much temperature increase the windings can withstand

Question 12

What is the Service Factor? (SF)

Answer 12

Amount of load the motor can deliver without overheating.

Question 13

What are the 3 common Service Factors?

Answer 13

SF 1.0 - Rated Load on nameplate
SF 1.15 - 115% Rated load
SF 1.25 - 125% Rated load

Question 14

When speed is low, torque is ____

Answer 14

High

Question 15

When speed is high, torque is ___

Answer 15

Low

Question 16

What is a C Face mount?

Answer 16

Motor supports driven unit (pump)

Question 17

What is a D Flange mount?

Answer 17

Motor is supported by driven unit (pump)

Question 18

What are the types of overload protection on single phase motors?

Answer 18

ATO, MTO

Question 19

What are the types of overload protection for 3 phase motors?

Answer 19

Thermostats, thermistors, and resistance temperature detectors

Question 20

What are the basic parts of AC motors?

Answer 20

Two main parts:
•Stator
•Rotor
Others:
•End Bracket
•Fan End Bracket
•Fan
•Fan Shroud
•Lifting Lug

Question 21

What are motor poles?

Answer 21

Number of windings

Question 22

The more poles in a motor, the ____ the RPM is and torque is proportionally ____

Answer 22

Lower, Higher

Question 23

What is slip?

Answer 23

Difference between synchronous speed and actual speed. (Between 1% and 5%)

Question 24

Which is more common, single phase or 3 phase? Why?

Answer 24

3 phase. Cheaper and more efficient. Considered the workhorse of industry (not ours)

Question 26

What is the primary problem with single phase motors?

Answer 26

Little to no start up torque.

Question 27

What are the methods of starting single phase motors?

Answer 27

Shaded Pole, Split Phase, Capacitor Start, and Perm Split Capacitor

Question 28

Describe Shaded Pole

Answer 28

Copper loop, called shading ring, surrounds part of the stator pole

Question 29

Describe Split Phase

Answer 29

Start windings positioned 90° from run windings

Question 30

Describe Capacitor Start

Answer 30

Has a capacitor in series with start winding. (Most commonly used in industry, more than double starting torque)