Singal phase induction motor mcq part -6

1. After the starting winding of a single phase induction motor is disconnected from supply, it continues to run only on
(a) running winding
(b) rotor winding
(c) field winding
(d) compensating winding

Ans: a

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

Ans: c

3. A.C. series motor as compared to D.C. series motor has
(a) smaller brush width
(b) less number of field turns
(c) more number of armature turns
(d) less air gap
(e) all of the above

Ans: e

4. Locked rotor current of a shaded pole motor is
(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

Ans: c

5. Speed control of a universal motor is achieved by
(a) varying field flux with tapped field windings
(b) connecting rheostat in series
(c) applying variable voltage by means of silicon controlled rectifier
(d) applying variable voltage by means of variable auto-transformer
(e) all of the above methods

Ans: e

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

Ans: d

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

Ans: a

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

Ans: d

9. The starting winding of a single-phase motor is placed in
(a) armature
(b) field
(c) rotor
(d) stator

Ans: d

10. The speed of a universal motor is usually reduced by using
(a) gearing
(b) belts
(c) brakes
(d) chains

Ans: a