Question 1

The ____ motor is a single-phase motor that starts based on the principle that like poles repel.&#10;A) universal&#10;B) repulsion-start, induction-run&#10;C) torque&#10;D) reversing split-phase

Accepted Answer

A repulsion-start, induction-run motor has a stator with a winding that is split into two parts, and the rotor has a winding with brushes that short out part of the rotor winding to create a repelling force, which starts the motor. Once the motor gets up to speed, the brushes move away from the shorted portion of the rotor winding, and the motor operates as an induction motor.

Question 2

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

Accepted Answer

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

Question 3

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

Accepted Answer

The speed of the rotor of an induction motor is always less than the synchronous speed and depends on the load it has to drive. It is commonly known as slip speed.

Question 4

What purpose does brush-shifting accomplish in a motor?&#10;A) Adjusts the rotor speed&#10;B) Compensates for hysteresis&#10;C) Changes the frequency&#10;D) Allows it to operate on AC or DC

Accepted Answer

Brush-shifting in motors is used to adjust the rotor speed by changing the position of the brushes relative to the commutator, thereby altering the timing of the commutation process and effectively controlling the speed.

Question 5

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

Accepted Answer

This is true.

Question 6

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 ____.&#10;A) output voltage in volts&#10;B) number of poles on the stator&#10;C) resistance of the rotor windings in ohms&#10;D) inductive reactance of the rotor in Henries

Accepted Answer

The synchronous speed of a motor is directly proportional to the frequency of the supply current and inversely proportional to the number of poles on the stator. Therefore, to determine synchronous speed, multiple 120 by the frequency of the supply current in Hertz and divide their product by the number of poles on the stator.

Question 7

The magnetic field of a two-pole induction motor completes ____ revolutions per minute when supplied with 60 Hz.&#10;A) 60&#10;B) 180&#10;C) 1800&#10;D) 3600

Accepted Answer

The magnetic field of a two-pole induction motor completes 3600 revolutions per minute (rpm) when supplied with 60 Hz, as the speed in rpm is calculated by (120 * frequency) / number of poles, which equals 3600 rpm for a 2-pole motor at 60 Hz.

Question 8

One method of making a single-phase motor self-starting is to apply the ____ principle.&#10;A) phase-splitting&#10;B) current-splitting&#10;C) voltage-splitting&#10;D) resistance-splitting

Accepted Answer

The phase-splitting principle involves introducing a phase shift between the main winding and the starter winding, which creates a rotating magnetic field that initiates the motor's rotation. This method is commonly used in capacitor-start and capacitor-start/capacitor-run single-phase motors. Current-splitting, voltage-splitting, and resistance-splitting are not valid methods for making a single-phase motor self-starting.

Question 9

A(n) ____ motor is an AC motor in which the rotor revolves at the same speed as the rotating magnetic field.&#10;A) high-frequency&#10;B) multispeed squirrel-cage&#10;C) polyphase synchronous&#10;D) adjustable-speed induction

Accepted Answer

A polyphase synchronous motor is an AC motor in which the rotor revolves at the same speed as the rotating magnetic field. The other options (A, B, and D) do not describe a synchronous motor.

Question 10

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.&#10;A) induction split-phase&#10;B) single-phase&#10;C) capacitor resistance-start&#10;D) capacitor split-phase

Accepted Answer

A capacitor-start, induction-run motor is also known as a capacitor split-phase motor. This type of motor uses a capacitor to provide extra torque during starting, allowing it to overcome higher inertia loads. It is commonly used in applications such as air compressors, pumps, and industrial machinery.

Question 11

Single-phase, ____ motors are started by means of a low-resistance short-circuited coil placed around one tip of each pole.&#10;A) permanent capacitor&#10;B) reversing&#10;C) resistance&#10;D) shaded-pole

Accepted Answer

The answer of Single-phase, ____ motors are started by means...

Question 12

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

Accepted Answer

The answer of One advantage of the wound-rotor induction motor...

Question 13

To reverse the direction of rotation of the rotor, you would ____.&#10;A) reverse the polarity of one of the fields&#10;B) reverse the polarity of both of the fields&#10;C) increase the operating frequency&#10;D) attach a permanent capacitor

Accepted Answer

The answer of To reverse the direction of rotation of...

Question 14

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

Accepted Answer

The answer of The induction motor is the most common...

Question 15

The difference between the synchronous speed and the rotor speed is called the ____ of the rotor.&#10;A) differential&#10;B) frequency&#10;C) phase difference&#10;D) slip

Accepted Answer

The answer of The difference between the synchronous speed and...

Deck 19: Ac Motors