Single Phase Induction Motors

51. Locked rotor current of a shaded pole motor is

  1. equal to full load current
  2. less than full load current
  3. slightly more than full load current
  4. several times the full load current

Correct answer: (C)
slightly more than full load current

52. Most of the fractional horsepower motors have either

  1. hard and annealed bearings
  2. ball or roller bearings
  3. soft and porous bearings
  4. plain or sleeve bearings

Correct answer: (D)
plain or sleeve bearings

53. Short-circuiter is used in

  1. repulsion induction motor
  2. repulsion motor
  3. repulsion start induction run motor
  4. none of the above

Correct answer: (C)
repulsion start induction run motor

54. Single phase induction motor usually operates on

  1. 0.6 power factor lagging
  2. 0.8 power factor lagging
  3. 0.8 power factor leading
  4. unity power factor

Correct answer: (A)
0.6 power factor lagging

55. Speed control of a universal motor is achieved by

  1. varying field flux with tapped field windings
  2. connecting rheostat in series
  3. applying variable voltage by means of silicon controlled rectifier
  4. applying variable voltage by means of variable auto-transformer
  5. all of the above methods

Correct answer: (E)
all of the above methods

56. Speed torque characteristic of a repulsion induction motor is similar to that of a D.C.

  1. shunt motor
  2. series motor
  3. compound motor
  4. separately excited motor

Correct answer: (C)
compound motor

57. Starting winding of a single phase motor of a refrigerator is disconnected from the circuit by means of a

  1. magnetic relay
  2. thermal relay
  3. centrifugal switch
  4. none of the above

Correct answer: (A)
magnetic relay

58. The capacitors used in single-phase capacitor motors have no

  1. voltage rating
  2. dielectric medium
  3. polarity marking
  4. definite value

Correct answer: (C)
polarity marking

59. The direction of rotation of an hysteresis motor is determined by

  1. interchanging the supply leads
  2. position of shaded pole with respect to main pole
  3. retentivity of the rotor material
  4. none of these

Correct answer: (B)
position of shaded pole with respect to main pole

60. The direction of rotation of universal motor can be reversed the by reversing the flow of current through

  1. armature winding
  2. field winding
  3. either armature winding or field winding
  4. none of the above

Correct answer: (C)
either armature winding or field winding

Previous
Page 6 of 11
Next
Copyright © EngineeringMCQ.com