Deck 19: Ac Motors

Question 1

Single-phase, ____ motors are started by means of a low-resistance short-circuited coil placed around one tip of each pole.

A) permanent capacitor
B) reversing
C) resistance
D) shaded-pole

Answer 1

D

Question 2

One advantage of the wound-rotor induction motor compared to the squirrel-cage motor is that it has lower initial cost and maintenance costs.

Answer 2

False

Question 3

What purpose does brush-shifting accomplish in a motor?

A) Adjusts the rotor speed
B) Compensates for hysteresis
C) Changes the frequency
D) Allows it to operate on AC or DC

Answer 3

A

Question 4

The induction motor is the most common type of AC motor.

Question 5

The speed of the rotor of an induction motor depends upon the synchronous speed and the load it must drive.

Question 6

The magnetic field of a two-pole induction motor completes ____ revolutions per minute when supplied with 60 Hz.

A) 60
B) 180
C) 1800
D) 3600

Question 7

The difference between the synchronous speed and the rotor speed is called the ____ of the rotor.

A) differential
B) frequency
C) phase difference
D) slip

Question 8

The ____ motor is a single-phase motor that starts based on the principle that like poles repel.

A) universal
B) repulsion-start, induction-run
C) torque
D) reversing split-phase

Question 9

To reverse the direction of rotation of the rotor, you would ____.

A) reverse the polarity of one of the fields
B) reverse the polarity of both of the fields
C) increase the operating frequency
D) attach a permanent capacitor

Question 10

A(n) ____ motor is an AC motor in which the rotor revolves at the same speed as the rotating magnetic field.

A) high-frequency
B) multispeed squirrel-cage
C) polyphase synchronous
D) adjustable-speed induction

Question 11

On the three-phase motor, the windings are arranged to produce a rotating magnetic field when connected to a three-phase source.

Question 12

The two main components of an induction motor are the stator and the conductor.

Question 13

A capacitor-start, induction-run motor called a(n) ____ motor is frequently used for installations requiring higher starting torque than is available from the resistance split-phase motor.

A) induction split-phase
B) single-phase
C) capacitor resistance-start
D) capacitor split-phase

Question 14

To determine the synchronous speed of a motor, multiple 120 by the frequency of the supply current in hertz and divide their product by the ____.

A) output voltage in volts
B) number of poles on the stator
C) resistance of the rotor windings in ohms
D) inductive reactance of the rotor in henries

Question 15

One method of making a single-phase motor self-starting is to apply the ____ principle.

A) phase-splitting
B) current-splitting
C) voltage-splitting
D) resistance-splitting