THREE PHASE INDUCTION MOTORS QUIZ

A 3 phase 440 v, 50 Hz induction motor has 4% slip. The frequency of rotor emf will be

50 Hz

200 Hz

20 Hz

2 Hz

TRUE ANSWER : ?
YOUR ANSWER : ?

The shaft of an induction motor is made of

Cast iron

Stainless steel

High speed steel

Carbon steel

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YOUR ANSWER : ?

If the frequency of 3-phase supply to the stator of a 3-phase induction motor is increased, then synchronous speed ______

Remains unchanged

None of the listed here

Is increased

Is decreased

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YOUR ANSWER : ?

In an induction motor if air gap increased

Bearing friction will reduce

Windage losses will be more

The power factor will be low

Copper loss will reduce

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The speed of a squirrel cage induction motor is changed by

Pole changing

Cascade control

None of the listed here

Rheostatic control

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For the same kVA rating, the leakage flux in induction motor is _______ that of transformer.

Less than

More than

None of the listed here

About the same

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YOUR ANSWER : ?

When the rotor of a 3-phase induction motor is blocked, the slip is _____

0.1

0

1

0.5

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YOUR ANSWER : ?

In the circle diagram for induction motor, the diameter of the circle represents

Rotor current

Running torque

Line voltage

Slip

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YOUR ANSWER : ?

As load on an induction motor goes on increasing

Its power factor goes on decreasing

Its power factor remains constant

Its power factor goes on increasing even after full load

Its power factor goes on increasing up to full load and then it falls again

TRUE ANSWER : ?
YOUR ANSWER : ?

If the supply voltage of a 3-phase induction motor is increased two times, then torque is _______

Decreased four times

Increased two times

Increased four times

Decreased two times

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YOUR ANSWER : ?

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