Polyphase Induction Motors - Interview Questions | Exam2Win

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41. If any two phases for an induction motor are interchanged

A. the motor will run in reverse direction

B. the motor will run at reduced speed

C. the motor will not run

D. the motor will burn

Explanation:

42. DOL starting of induction motors is usually restricted to

A. low horsepower motors

B. variable speed motors

C. high horsepower motors

D. high speed motors

Explanation:

43. In case of 3-phase induction motors, plugging means

A. pulling the motor directly on line without a starter

B. locking of rotor due to harmonics

C. starting the motor on load which is more than the rated load

D. interchanging two supply phases for quick stopping

Explanation:

44. In a three-phase induction motor

A. power factor at starting is high as compared to that while running

B. power factor at starting is low as compared to that while running

C. power factor at starting in the same as that while running

D. power factor at starting is low as compared to that while running

Explanation:

45. In case the air gap in an induction motor is increased

A. the magnetising current of the rotor will decrease

B. the power factor will decrease

C. speed of motor will increase

D. the windage losses will increase

Explanation:

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