Single Phase Induction Motors Multiple Choice Questions and Answers In English-04

1. Which of the following motor will give the highest starting torque ?

(A) D.C. shunt motor
(B) Schrage motor
(C) Repulsion start and induction run motor
(D) Universal motor
Ans: B

2. Which of the following motors is preferred for tape-recorders ?
(A) Shaded pole motor
(B) Hysteresis motor
(C) Two value capacitor motor
(D) Universal motor
Ans: B

3. In case of a shaded pole motor the direction of rotation of the motor is
(A) from main pole to shaded pole
(B) from shaded pole to main pole
(C) either of the above depending on voltage
(D) either of the above depending on power factor
Ans: A

4. Which of the following single-phase motors is suitable for timing and control purposes ?
(A) Reluctance motor
(B) Series motor
(C) Repulsion motor
(D) Universal motor
Ans: A

5. Which of the following motors will operate at high power factor ?
(A) Shaped pole motor
(B) Split phase motor
(C) Capacitor start motor
(D) Capacitor run motor
Ans: D

6. The repulsion-start induction-run motor is used because of
(A) good power factor
(B) high efficiency
(C) minimum cost
(D) high starting torque
Ans: D

7. A hysteresis motor works on the principle of
(A) hysteresis loss
(B) magnetisation of rotor
(C) eddy current loss
(D) electromagnetic induction
Ans: A

8. In case of high speed universal motor which of the following needs more attention ?
(A) End play
(B) Air gap
(C) Insulation in rotor
(D) Balancing of rotor
Ans: D

9. The wattage of motor for driving domestic sewing machine will be around
(A) 100 to 150 W
(B) 40 to 75 W
(C) 10 to 30 W
(D) 5 to 10 W
Ans: A

10. Which of the following single-phase motors has relatively poor starting torque ?
(A) Universal motor
(B) Repulsion motor
(C) Capacitor motor
(D) All single phase motors have zero starting torque
Ans: C

11. The wattage rating for a ceiling fan motor will be in the range
(A) 200 to 250 W
(B) 250 to 500 W
(C) 50 to 150 W
(D) 10 to 20 W
Ans: C

12. The speed of a universal motor is generally reduced by using
(A) gear trains
(B) V-belts
(C) brakes
(D) chains
Ans: A

13. Which of the following motors can be used for unity power factor ?
(A) Capacitor run motor
(B) Shaded pole motor
(C) Hysteresis motor
(D) Schrage motor
Ans: D

14. When a D.C. series motor is connected to A.C. supply, the power factor will be low because of
(A) high inductance of field and armature circuits
(B) induced current in rotor due to variations of flux
(C) fine copper wire winding
(D) none of the above
Ans: A

15. The direction of rotation of universal motor can be reversed the by reversing the flow of current through
(A) armature winding
(B) field winding
(C) either armature winding or field winding
(D) none of the above
Ans: C

16. Which type of load is offered by cranes and hoists ?
(A) Gradually varying load
(B) Non-reversing, no-load start
(C) Reversing, light start
(D) Reversing, heavy start
Ans: D

17. 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

18. 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

19. 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

20. In which single-phase motor, the rotor has no teeth or winding ?
(A) Split phase motor
(B) Reluctance motor
(C) Hysteresis motor
(D) Universal motor
Ans: C