single phase induction motors MCQs – Page 2

Practise focused single phase induction motors questions with marked answers for exam preparation and subject revision.

single phase induction motors Mcqs
21. Centrifugal switch disconnects the auxiliary winding of the motor at about ______ percent of synchronous speed?
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A. 30 to 40

B. 100

C. 70 to 80

D. 80 to 90

22. The motor used on small lathes is usually_________?
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A. D.C. shunt motor

B. 3-phase synchronous motor

C. universal motor

D. single-phase capacitor run motor
23. In repulsion motor direction of rotation of motor____________?
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A. is independent of brush shift

B. is opposite to that of brush shift

C. is the same as that of brush shift
24. The motor used for the compressors is____________?
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A. capacitor-start capacitor-run motor

B. d.c. series motor

C. reluctance motor

D. shaded pole motor

25. Which of the following motors can be run on AC. as well as D.C. supply ?
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A. Reluctance motor

B. Synchronous motor

C. Universal motor

D. Repulsion motor

26. The rotor slots, in an induction motor, are usually not quite parallel to the shaft because it_____________?
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A. helps in reducing the tendency of the rotor teeth to remain under the stator teeth

B. improves the efficiency

C. helps the rotor teeth to remain under the stator teeth

D. improves the power factor

27. Which of the following motors will operate at high power factor ?
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A. Split phase motor

B. Capacitor run motor

C. Shaped pole motor

D. Capacitor start motor

28. Which of the following motors can be used for unity power factor ?
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A. Shaded pole motor

B. Schrage motor

C. Capacitor run motor

D. Hysteresis motor

29. The rotor developed by a single-phase motor at starting is___________?
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A. less than the rated torque

B. zero

C. more than i.he rated torque

D. rated torque

30. Speed torque characteristic of a repulsion induction motor is similar to that of a D.C____________?
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A. series motor

B. shunt motor

C. compound motor

D. separately excited motor

31. Which of the following single-phase motors is suitable for timing and control purposes ?
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A. Series motor

B. Repulsion motor

C. Universal motor

D. Reluctance motor
32. In a universal motor, the most common cause of brush sparking is___________?
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A. shorted armature winding

B. shorted field winding

C. open armature winding

D. high commutator mica

E. all of the above
33. In a split phase motor, the running winding should have?
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A. high resistance and low inductance

B. low resistance and high inductance

C. low resistance as well as low inductiance

D. high resistance as well as high inductance

34. If a D.C. series motor is operated on A.C. supply, it will____________?
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A. spark excessively

B. have poor power factor

C. all of the above

D. have poor efficiency

35. When a D.C. series motor is connected to A.C. supply, the power factor will be low because of____________?
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A. high inductance of field and armature circuits

B. induced current in rotor due to variations of flux

C. none of the above

D. fine copper wire winding

36. Which of the following motors is preferred for tape-recorders ?
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A. Hysteresis motor

B. Two value capacitor motor

C. Universal motor

D. Shaded pole motor

37. In A.C. series motor compensating winding is employed to_____________?
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A. none of the above

B. increase the torque

C. reduce sparking at the brushes

D. reduce the effects of armature reaction

38. In a capacitor start single-phase motor, when capacitor is replaced by a resistance____________?
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A. the motor will consume less power

B. torque will increase

C. motor will run in reverse direction

D. motor will continue to run in same direction
39. Locked rotor current of a shaded pole motor is____________?
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A. several times the full load current

B. slightly more than full load current

C. less than full load current

D. equal to full load current

40. In split-phase motor auxiliary winding is of___________?
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A. thick wire placed at the top of the slots

B. thin wire placed at the top of the slots

C. thin wire placed at the bottom of the slots

D. thick wire placed at the bottom of the slots