Multiple Choice Question (MCQ) of Induction Motors page-4

31. Advantage of slip ring induction motor over squirrel cage induction motor is

a) Suitability of high speeds
b) Higher efficiency
c) Higher power factor
d) That it can be started using factor resistance

Ans: (d)

32. In an induction motor, the rotor input is 600 W and slip is 4%. The rotor copper loss is

a) 700 W
b) 625 W
c) 600 W
d) 650 W

Ans: (b)

33. The starting torque of a cage rotor induction motor can be increased by using rotor having

a) Low inductance and low resistance
b) Low inductance and high resistance
c) High inductance and high resistance
d) High inductance and low resistance

Ans: (c)

34. For smooth starting of three-phase squirrel cage induction motor, the starting method preferred is

a) Rotor resistance
b) Star-delta
c) Auto-transformer
d) Stator resistance

Ans: (c)

35. Large air gap in an induction motor results in

a) Reduced noise
b) Reduced pulsation losses
c) Better cooling
d) Increased overload capacity

Ans: (b)

36. The power factor of star connected induction motor is 0.5. On being connected in delta, the power factor will?

a) Increase
b) Reduce
c) Remain the same
d) Become zero

Ans: (b)

37. Simplest method of eliminating the harmonic induction torque is

a) Integral slot winding
b) Chording
c) Skewing
d) None of these

Ans: (b)

38. Any odd harmonic in the current of an induction motor will result in magnetic field which

a) Is stationary relative to the field of the fundamental
b) Rotates in forward direction at the harmonic speed
c) Rotates in backward direction
d) Oscillates at harmonic frequency

Ans: (c)

39. The drive generally used for lathe machines are

a) Dc shunt motors
b) Slip ring induction motors
c) Synchronous motors
d) Squirrel cage induction motors

Ans: (d)

40. Cogging of motor implies that motor

a) Refuses to start at load
b) Refuses to start at no load
c) Runs at low speed and then stops
d) Runs at very low speed

Ans: (b)

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Multiple Choice Question (MCQ) of Induction Motors page-4

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