Important interview questions for an induction motor?

INDUCTION MOTOR

1.What is an induction motor?

an alternating current motor in which torque is produced by the reaction between a varying magnetic field generated in the stator and the current induced in the coils of the rotor. It is also called as asynchronous motor.

2.what are the types of induction motor?

Single phase induction motor

a) split phase induction motor

b) capacitor start induction motor

c) capacitor start capacitor run induction motor

d) shaded pole induction motor

Three phase induction motor

a) squirrel cage induction motor

b) slip ring induction motor

3.what is slip in an induction motor?

It is the difference between the flux speed(Ns) and rotor speed(N).

Speed of the rotor of an induction motor is always less than its synchronous speed.

%slip = (Ns-N) *100/Ns.

4.what are the methods of measuring slip?

a) measurement of rotor speed

b) measurement of rotor frequency

c) stroboscopic method

5.what are the method of speed control in three phase induction motor?

a)control from stator side:

Changing the supply frequency

Changing the supply voltage

Changing the number of stator poles

b) control from rotor side:

Injecting resistance in rotor circuit

Injecting EMFs in the rotor circuit

Various ways of cascade connection

6.what are the test of induction motor?

a)No load test

b) locked rotor test

c) break down torque load performance test

d) temperature test

e) determination of efficiency test

f) stray load loss test

7.what are the starters used for starting induction motor?

a) direct online starter

b) star delta starter

c) auto transformer starter

d) resistance starter

e) series reactance starter

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