Question 1

Locked rotor current of a shaded pole motor is

Accepted Answer

A)  equal to full load current
B)  less than full load current
C)  slightly more than full load current
D)  several times the full load current C

Question 2

Speed control of a universal motor is achieved by

Accepted Answer

A)  varying field flux with tapped field windings
B)  connecting rheostat in series
C)  applying variable voltage by means of silicon controlled rectifier
D)  all of the above methods D

Question 3

The starting winding of a single-phase motor is placed in

Accepted Answer

A)  armature
B)  field
C)  rotor
D)  stator D

Question 4

After the starting winding of a single phase induction motor is disconnected from supply, it continues to run only on

Accepted Answer

A)  running winding
B)  rotor winding
C)  field winding
D)  compensating winding

Question 5

Hysteresis motor is particularly useful for high-quality record players and tape- recorders because

Accepted Answer

A)  it revolves synchronously
B)  it is not subject to any magnetic or mechanical vibrations
C)  it can be easily manufactured in extremely small sizes of upto 1 W output
D)  it develops hysteresis torque which is extremely steady both in amplitude and phase

Question 6

Which of the following statements regarding hysteresis motor is in incorrect ?

Accepted Answer

A)  It is extremely sensitive to fluctuations in supply voltage
B)  Its high starting torque is due to its high rotor hysteresis loss
C)  It is extremely quiet in operation
D)  It accelerates from rest to full-speed almost instantaneously

Question 7

Which of the following statements regarding single-phase induction motoris correct ?

Accepted Answer

A)  It requires only one winding
B)  It can rotate in one direction only
C)  It is self-starting
D)  It is not self-starting

Question 8

The speed of a universal motor is usually reduced by using

Accepted Answer

A)  gearing
B)  belts
C)  brakes
D)  chains

Question 9

A.C. series motor as compared to D.C. series motor has

Accepted Answer

A)  smaller brush width
B)  less number of field turns
C)  more number of armature turns
D)  all of the above

Question 10

Which of the following statements regarding repulsion-start induction motor is incorrect ?

Accepted Answer

A)  It requires more maintenance of commutator and other mechanical devices
B)  It makes quite a bit of noise on starting
C)  In fractional horse power motors, it has replaced the capacitor motors
D)  It is not easily reversed

Exam 5: Single-Phase Induction Motors and Their Features