THREE PHASE INDUCTION MOTORS QUIZ

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

Same

Any of the listed here

Smaller

Bigger

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

Increasing rotor resistance

None of the listed here

Increasing rotor reactance

Decreasing rotor resistance

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The term cogging is associated with

Dc series motors

Three phase transformer

Induction motors

Compound generators

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The stator of a three phase induction motor produces _______ magnetic field.

Steady

Alternating

Rotating

None of the listed here

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Slip of an induction motor is negative when

Rotor speed is more than the synchronous speed of the field and are in the same direction

Magnetic field and rotor rotate in opposite direction

Rotor speed is less than the synchronous speed of the field and are in the same direction

None of these

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DOL starting of induction motors is usually restricted to

Variable speed motors

Low horsepower motors

High horsepower motors

High speed motors

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

Increased four times

Decreased four times

Decreased two times

Increased two times

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The induction motor has lagging power factor during

Operation only

Starting only

Both starting and operation

None of the listed here

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Slip rings are usually made of

Phospor bronze

Aluminium

Carbon

Copper

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If a 4 pole induction motor has a synchronous speed of 1500 rpm, then supply frequency is _____

60 Hz

None of the listed here

25 Hz

50 Hz

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