THREE PHASE INDUCTION MOTORS QUIZ

The starting torque of an induction motor is maximum when rotor resistance per phase is _____ rotor reactance / phase.

None of the listed here

Two times

Equal to

Four times

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

30 to 50%

15 to 20 %

5%

10 to 15%

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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 _______

20 W

980 W

200 W

500 W

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DOL starting of induction motors is usually restricted to

Variable speed motors

High speed motors

High horsepower motors

Low horsepower motors

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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 maximum torque in an induction motor depends on

Rotor inductive reactance

All of the listed here

Square of supply voltage

Frequency

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If the air gap between the rotor and stator of a 3-phase induction motor is increased, then_______

Leakage reactances are decreased

None of the listed here

Leakage reactances are increased

No load current is decreased

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In a double squirrel cage induction motor, the outer cage winding has _______

High resistance

Low resistance

High inductance

None of the listed here

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The direction of rotation of field in a 3 phase induction motor depends upon _____

Phase sequence of supply voltage

Supply frequency

Number of poles

Magnitude of supply voltage

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For higher efficiency of 3-phase induction motor, the slip should be

1

Large

As small as possible

Very large

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