THREE PHASE INDUCTION MOTORS QUIZ

Size of a high speed motor as compared to low speed motor for the same HP will be

Bigger

Same

Any of the listed here

Smaller

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In a squirrel cage rotor, the bars are not placed parallel to the shaft but are skewed to have ______

None of the listed here

Greater mechanical strength

Uniform torque

Less rotor losses

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The rotor of an induction motor runs at

Above synchronous speed

Synchronous speed

Any of the above

Below synchronous speed

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DOL starting of induction motors is usually restricted to

Low horsepower motors

High horsepower motors

Variable speed motors

High speed motors

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

None of the listed here

Equal to

Four times

Two times

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

Decreased four times

Increased four times

Increased two times

Decreased two times

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A four speed squirrel cage induction motor uses______ stator windings.

One

Four

Three

Two

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The synchronous speed of a 3-phase induction motor having 20 poles and connected to a 50 Hz source is _____

600 rpm

300 rpm

1200 rpm

1000 rpm

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In an induction motor if air gap increased

Bearing friction will reduce

The power factor will be low

Copper loss will reduce

Windage losses will be more

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

65%

40%

None of the listed here

90%

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