THREE PHASE INDUCTION MOTORS QUIZ

The shaft of induction motor is made of

Flexible

Hollow

Any of the listed here

Stiff

TRUE ANSWER : ?
YOUR ANSWER : ?

The approximate efficiency of a 3-phase , 50 Hz, 4 pole induction motor running at 1350 rpm is ______

None of the listed here

65%

90%

40%

TRUE ANSWER : ?
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The induction motor has lagging power factor during

Starting only

Both starting and operation

Operation only

None of the listed here

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The speed of a squirrel-cage induction motor can be controlled by all of the following except

Changing winding resistance

Reducing supply voltage

Changing supply frequency

Changing number of poles

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Insertion of resistance in the rotor of an induction motor to develop a given torque

Rotor current remains same

Increases the rotor current

Rotor current becomes zero

Decreases the rotor current

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YOUR ANSWER : ?

A wound rotor motor is mainly used in applications where ______

Speed control is required

Less costly motor is not required

High rotor resistance is required during running

High starting torque is required

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The starting torque of a 3-phase induction motor is _______ supply voltage.

Independent of

None of the listed here

Directly proportional to sqaure of

Directly proportional to

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Less maintenance troubles are experienced in case of

None of these

Squirrel cage induction motor

Both (A) and (B)

Slip ring induction motor

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In an induction motor, the ratio of rotor cu loss and rotor input is given by

1/S

S/1-S

1-S

S

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If an induction motor is running at slip S, then rotor output is ______

(1-S) × rotor input

(S-1) × rotor input

(1+S) × rotor input

S × rotor input

TRUE ANSWER : ?
YOUR ANSWER : ?

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