single phase induction motors MCQs – Page 3

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

single phase induction motors Mcqs
41. Which of the following statements regarding two value capacitor motor is incorrect ?
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A. It has low starting as well as rushing currents

B. It has high starting torque

C. It is a reversing motor

D. It is preferred to permanent-split single-value capacitor motor where frequent reversals are required
42. In which single-phase motor, the rotor has no teeth or winding ?
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A. Universal motor

B. Split phase motor

C. Reluctance motor

D. Hysteresis motor
43. In a capacitor start and run motors the function of the running capacitor in series with the auxiliary winding is to_______________?
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A. to improve torque

B. reduce fluctuations in torque

C. improve power factor

D. increase overload capacity

44. The electric motor used in portable drills is__________?
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A. capacitor run motor

B. universal motor

C. repulsion motor

D. hysteresis motor

45. As hysteresis motors are free from mechanical and magnetic vibrations therefore these are considered as suitable for__________?
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A. fans

B. sound equipment

C. mixer grinders

D. blowers

46. The direction of rotation of an hysteresis motor is determined by____________?
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A. interchanging the supply leads

B. retentivity of the rotor material

C. position of shaded pole with respect to main pole

D. none of these

47. In repulsion motor, zero torque is developed when___________?
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A. brush axis is 45 electrical to field axis

B. brush axis coincides with the field axis

C. brush axis is 90 electrical to field axis

D. both B. and (c)
48. Short-circuiter is used in_____________?
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A. none of the above

B. repulsion induction motor

C. repulsion start induction run motor

D. repulsion motor

49. The capacitors used in single-phase capacitor motors have no__________?
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A. voltage rating

B. dielectric medium

C. polarity marking

D. definite value

50. The repulsion-start induction-run motor is used because of___________?
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A. high starting torque

B. good power factor

C. minimum cost

D. high efficiency

51. If a single phase induction motor runs slower than normal, the most likely defect is_____________?
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A. open-circuit in the winding

B. short-circuit in the winding

C. worn bearings

D. none of the above

52. Which of the following statements regarding single-phase induction motors correct?
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A. It is not self-starting

B. It can rotate in one direction only

C. It requires only one winding

D. It is self-starting

53. Burning out of winding is due to___________?
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A. capacitor value hiving changed

B. none of the above

C. open circuiting of capacitor

D. short circuited capacitor
54. Which motor is normally free from mechanical and magnetic vibrations ?
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A. Universal motor

B. Shaded pole motor

C. Hysteresis motor

D. Split phase motor

55. In a two value capacitor motor, the capacitor used for running purposes is_______________?
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A. a.c. electrolytic type

B. air capacitor

C. paper spaced oil filled type

D. ceramic type

56. In case of a shaded pole motor the direction of rotation of the motor is__________?
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A. from shaded pole to main pole

B. from main pole to shaded pole

C. either of the above depending on power factor

D. either of the above depending on voltage

57. The wattage rating for a ceiling fan motor will be in the range_________?
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A. 50 to 150 W

B. 250 to 500 W

C. 200 to 250 W

D. 10 to 20 W

58. Which of the following statements regarding a reluctance motor is incorrect ?
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A. Its squirrel cage-rotor is of unsym-metrical magnetic construction in order to vary reluctance path between stator and rotor

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. It cannot be reversed, ordinarily
59. The purpose of stator winding in the compensated repulsion motor is to_____________?
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A. improve power factor and provide better speed regulation

B. prevent hunting in the motor

C. eliminate armature reaction

D. provide mechanical balance

60. In a capacitor start motor, the phase displacement between starting and running winding can be nearly__________?
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A. 60

B. 30

C. 10

D. 90