THREE PHASE INDUCTION MOTORS QUIZ

DOL starting of induction motors is usually restricted to

High speed motors

Variable speed motors

Low horsepower motors

High horsepower motors

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The no load speed of an induction motor depends on

The maximum flux/poles

The supply frequency

The number of its poles

Both supply frequency and number of poles

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A 3 phase induction motor is running at 2% slip. If the input to rotor is 1000 W, then mechanical power developed by the motor is _______

500 W

200 W

980 W

20 W

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Friction and windage loss of a 3 phase induction motor are

Remains the same at all loads

Minimum at no load

None of the listed here

Maximum at no load

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

Line voltage

Rotor current

Running torque

Slip

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The magnetising current drawn by a 3 phase induction motor is about _______ of full load stator current.

10 to 15%

5%

15 to 20 %

30 to 50%

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

Increased four times

Increased two times

Decreased two times

Decreased four times

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5 H.P., 50Hz, 3-phase, 440 V, induction motors are available for the following r.p.m. Which motor will be the costliest?

730 rpm

1000 rpm

2880 rpm

1440 rpm

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The condition of induction motor on load resemble those of a transformer whose secondady is _______

Short circuited

Supplying a variable resistive load

None of the listed here

Open circuited

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