Polyphase Induction Motors - Interview Questions | Exam2Win

Take a timed mock test specifically for Polyphase Induction Motors.

36. The 'crawling" in an induction motor is caused by

A. high loads

B. low voltage supply

C. improper design of machine

D. harmonics developed in the motor

Explanation:

37. It is advisable to avoid line-starting of induction motor and use starter because

A. motor takes five to seven times its full load current

B. it will pick-up very high speed and may go out of step

C. it will run in reverse direction

D. starting torque is very high

Explanation:

38. Low voltage at motor terminals is due to

A. inadequate motor wiring

B. poorely regulated power supply

C. any one of the above

D. none of the above

Explanation:

39. Slip of an induction motor is negative when

A. magnetic field and rotor rotate in opposite direction

B. rotor speed is less than the syn-chronous speed of the field and are in the same direction

C. rotor speed is more than the syn-chronous speed of the field and are in the same direction

D. none of the above

Explanation:

40. In three-phase squirrel-cage induction motors

A. rotor conductor ends are short-circuited through slip rings

B. rotor conductors are short-circuited through end rings

C. rotor conductors are kept open

D. rotor conductors are connected to insulation

Explanation:

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