Deck 9: Motors and Controllers

Question 1

The speed of the rotating magnetic field of a polyphase ac motor is called ____ speed.

A) variable
B) critical
C) synchronous
D) proportional

Answer 1

C

Question 2

The ____ operates like an electric check valve; it permits the current to flow through it in only one direction.

A) inductor
B) diode
C) resistor
D) capacitor

Answer 2

B

Question 3

An induction motor is much like a(n) ____, except that the secondary winding and core are mounted on a shaft set in bearings.

A) limit switch
B) ohmmeter
C) transformer
D) voltmeter

Answer 3

C

Question 4

The torque reaches maximum when the rotor and stator currents are ____ with each other.

A) in phase
B) 60 degrees out of phase
C) 120 degrees out of phase
D) 150 degrees out of phase

Question 5

A(n) ____ uses two SCRs and two diodes.

A) integrated circuit
B) transistor
C) bridge rectifier
D) inductor

Question 6

What is the role of interpoles in dc motors?

Question 7

The speed of the wound-rotor induction motor can be controlled by the amount of ____ connected in the rotor circuit.

A) capacitance
B) voltage
C) resistance
D) inductance

Question 8

How do primary resistance starters work?

Question 9

Although the ____ compound motor gives a more constant speed at all loads, the motor is somewhat unstable.

A) armature
B) shunt
C) cumulative
D) differential

Question 10

Most dual-voltage single-phase motors will be of the ____ type, which contains both run and starting windings.

A) monophase
B) split-phase
C) biphase
D) schematic

Question 11

SCRs and GTOs are ____ and have the ability to handle a greater amount of current than transistors.

A) thyristors
B) integrated circuits
C) resistors
D) capacitors

Question 12

Describe how rotation results in the squirrel-type induction motor.

Question 13

What is the significance of the IGBT?

Question 14

Most dual-voltage motors bring out ____ "T" leads at the terminal box.

A) three
B) six
C) nine
D) ten

Question 15

Three-phase motors can be constructed to operate in either wye or ____.

A) delta
B) star
C) Kennelly
D) cycle

Question 16

A six-pole motor has a coil span of ____.

A) 60
B) 90
C) 120
D) 180

Question 17

What factors play a role in the performance of dc motors?

Question 18

In a machine that has a 3-phase motor rated at 460 volts, the current required by each machine is based on the ____ of the motor.

A) efficiency
B) volts
C) power factor
D) horsepower rating

Question 19

The force acting at the rim of the rotor multiplied by the radius from the center of the rotor is called the ____.

A) horsepower
B) torque
C) rotor speed
D) angular momentum

Question 20

Direct-current compound motors contain a rotating armature and a(n) ____ field.

A) stationary
B) interpole
C) commutator
D) brush