Deck 15: Electric Motors and Starting Components

Question 1

The start winding should drop out of the circuit once the motor has reached about __________% of its rated speed.

A) 50
B) 70
C) 90
D) 100

Answer 1

B

Question 2

Capacitors are rated in which of the following?

A) ohms
B) watts
C) microfarads
D) microns

Answer 2

C

Question 3

The run winding has fewer turns than the start winding on a split-phase motor.

Answer 3

True

Question 4

ECM motors are less efficient than PSC motors.

Question 5

Which type of motor does not require the use of start components?

A) shaded-pole
B) PSC
C) CSCR
D) three-phase
E) both a and d

Question 6

Start capacitors are filled with oil and enclosed in a metal case.

Question 7

A start capacitor is wired in __________ with the start winding of an electric motor.

A) series
B) parallel
C) either series or parallel
D) neither series nor parallel

Question 8

Run capacitors are filled with oil and are enclosed in a metal case.

Question 9

Single-phase motors have __________ windings.

A) 1
B) 2
C) 3
D) 4

Question 10

The windings are located in which part of the motor?

A) rotor
B) stator
C) either a or b
D) it depends on the type of motor

Question 11

Which split-phase motor has the lowest starting torque?

A) PSC
B) CSIR
C) CSCR
D) three-phase

Question 12

Some three-phase motors can operate on 220 and 440 volts.

Question 13

When a split-phase motor is starting, both the start and run windings must be energized.

Question 14

Shaded-pole motors are rated in __________.

A) watts
B) horsepower
C) tons
D) Btus

Question 15

Shaded-pole motors have no start and run windings.

Question 16

The start winding on a split-phase motor has a lower resistance than the run winding..

Question 17

The LRA of an electric motor is approximately __________ times that of the RLA.

A) 2
B) 5
C) 7
D) 10

Question 18

Three-phase motors can be 120 volts.

Question 19

The phase angle on a split-phase motor is about __________ degrees.

A) 10
B) 20
C) 30
D) 40

Question 20

When a split-phase motor is running, both the start and run windings must be energized.

Question 21

The power factor of resistive circuits is 1, so the power that is produced is calculated by what formula?

Question 22

If the power factor in an inductive circuit is 0.5, the voltage is 100 volts and the amperage is 5 amps, the calculated power will be __________.

Question 23

List five types of electric motors commonly found in HVAC equipment.

Question 24

The positive temperature coefficient (PTC) is a __________, or variable resistance device, whose resistance __________ as the sensed temperature increases. When cool, the resistance of the device is very __________. When cool, both the start and run windings of the motor are in the __________ electric circuit and __________ voltage is being supplied to the start winding.

Question 25

The coil of a current magnetic relay is wired:

A) in series with the start winding.
B) in series with the run winding.
C) in parallel with the common winding.
D) in parallel with the run winding.

Question 26

Which phase angle is generated by a three-phase motor?

A) 30
B) 90
C) 120
D) 180

Question 27

List three devices used to remove the start winding from the circuit after the motor has started.

Question 28

What do the following acronyms stand for when referring to electric motors? LRA RLA FLA

Question 29

When checking resistance on a split-phase motor, common-to-run will be the __________ ohm reading, common-to-start will be the __________ ohm reading, and start-to-run will be the __________ ohm reading.

A) high, medium, low
B) low, medium, high
C) medium, low, high
D) medium, high, low

Question 30

Energy efficient systems often incorporate __________ motors to turn the system blowers and fans. These motors are very unique. They are powered by __________ power, but actually operate as __________ motors.