Deck 9: Motors and Controllers

Question 1

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

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

Answer 1

A

Question 2

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

Answer 2

D

Question 3

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

Answer 3

B

Question 4

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 5

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

Question 6

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 7

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

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

Question 8

How do primary resistance starters work?

Question 9

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

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

Question 10

What is the role of interpoles in dc motors?

Question 11

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 12

What is the significance of the IGBT?

Question 13

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 14

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

Question 15

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 16

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

Question 17

A(n) uses two SCRs and two diodes.

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

Question 18

Most dual­voltage motors bring out "T" leads at the terminal box.

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

Question 19

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

Question 20

A six-pole motor has a coil span of .

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