Single Phase Induction Motors Multiple Choice Questions and Answers In English -02

1. In repulsion motor, maximum torque is developed when
(A) brush axis is at 45° electrical to the field axis
(B) brush axis coincides with the field axis
(C) brush axis is at 90° electrical to the field axis
(D) none of the above
Ans: A

2. In a ceiling fan employing capacitor run motor
(A) secondary winding surrounds the primary winding
(B) primary winding surrounds the secondary winding
(C) both are usual arrangements
(D) none of the above
Ans: A

3. The shaded pole motor is used for
(A) high starting torque
(B) low starting torque
(C) medium starting torque
(D) very high starting torque
Ans: B

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. Which of the following statements regarding single-phase induction motors 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

6. Which of the following statements regarding two value capacitor motor is incorrect ?
(A) It is a reversing motor
(B) It is preferred to permanent-split single-value capacitor motor where frequent reversals are required
(C) It has low starting as well as rushing currents
(D) It has high starting torque
Ans: B

7. Two-value capacitor motor finds increased application as compressor motor in small home air-conditioners
because
(A) it is comparatively cheaper
(B) it has almost non-destructible capacitor
(C) it has low starting as well as running currents at relatively high power factor
(D) it is quiet in operation
Ans: C

8. If the centrifugal switch of a two-value capacitor motor using two capacitors fails to open then
(A) motor will not come up to speed
(B) motor will not carry the load
(C) current drawn by the motor will be excessively high
(D) electrolytic capacitor will, in all probability, suffer break down
Ans: D

9. 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 up to 1 W output
(D) it develops hysteresis torque which is extremely steady both in amplitude and phase
Ans: D

10. 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

11. Which of the following statements regarding a reluctance motor is incorrect ?
(A) It cannot be reversed, ordinarily
(B) It requires no D.C. field excitation for its operation
(C) It is nothing else but a single-phase, salient pole synchronous-induction motor
(D) Its squirrel cage-rotor is of unsymmetrical magnetic construction in order to vary reluctance path between stator and rotor
Ans: A

12. A universal motor is one which
(A) can be operated either on D.C. or A.C. supply at approximately the same speed and output
(B) can be marketed internationally
(C) runs at dangerously high speed on no-load

(D) none of the above
Ans: A

13. A repulsion motor is equipped with
(A) slip rings
(B) commutator
(C) both (A) and (B)
(D) none of the above
Ans: B

14. The starting winding of a single-phase motor is placed in
(A) armature
(B) field
(C) rotor
(D) stator
Ans: D

15. The speed of a universal motor is usually reduced by using
(A) gearing
(B) belts
(C) brakes
(D) chains
Ans: A

16. If the centrifugal switch does not open at 70 to 80 percent of synchronous speed of motor, it would result in
(A) damage to the starting winding
(B) damage to the centrifugal switch
(C) overloading of running winding
(D) none of the above
Ans: A

17. Speed torque characteristic of a repulsion induction motor is similar to that of a D.C.
(A) shunt motor
(B) series motor
(C) compound motor
(D) separately excited motor
Ans: C

18. 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

19. A shaded pole motor does not possess
(A) centrifugal switch
(B) capacitor
(C) commutator
(D) all of the above
Ans: D

20. In a A.C. series motor armature coils are usually connected to commutator
(A) through resistance
(B) through reactances
(C) through capacitors
(D) solidly
Ans: A