THREE PHASE INDUCTION MOTORS QUIZ

If any two phases for an induction motor are interchanged

The motor will run at reduced speed

The motor will run in reverse direction

The motor will not run

The motor will burn

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

Changing number of poles

Changing supply frequency

Reducing supply voltage

Changing winding resistance

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If the rotor slots are made deeper, rotor resistance is ______

None of the listed here

Decreased at starting

Increased under running conditions

Increased at starting

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As load on an induction motor goes on increasing

Its power factor remains constant

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

Its power factor goes on decreasing

Its power factor goes on increasing even after full load

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The 3- phase induction motor is so designed that the rotor should have ______ under running conditions.

high resistance

High reactance

Low resistance

Large slip

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A high starting torque can be obtained in a 3phase induction motor by _______

Increasing rotor resistance

Decreasing rotor resistance

Increasing rotor reactance

None of the listed here

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When a 3-phase induction motor is at no load, the slip is ______

0.2

0.5

Practically zero

1

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Less maintenance troubles are experienced in terms of

Both squirrel cage and slip ring

Slip ring induction motor

Squirrel cage induction motor

None of the listed here

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The crawling in an induction motor is caused by

High loads

Improper design of machine

Harmonics developed in the rotor

Low voltage supply

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An induction motor with 1000 r.p.m. speed will have

4 poles

8 poles

2 poles

6 poles

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