THREE PHASE INDUCTION MOTORS QUIZ

The starting torque of a squirrel cage induction motor is

Slightly more than full load torque

Negligible

Same as full load torque

Low

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

None of the listed here

50 Hz

25 Hz

60 Hz

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For the same kVA rating, the leakage flux in induction motor is _______ that of transformer.

More than

None of the listed here

Less than

About the same

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The efficiency of an induction motor can be expected to be nearly

60 to 90%

99%

95 to 98 %

80 to 90%

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The frame of an induction motor is usually made of

Bronze

Aluminium

Cast iron

Silicon steel

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In a squirrel cage induction motor, the number of stator slots is _______ rotor slots.

Either more or less than the number of

Always greater than the number of

Always less than the number of

Always eqaul to the number of

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If a 3-phase induction motor is running at slip S, then rotor copper loss is equal to

S × rotor input

None of the listed here

(1+S) × rotor input

(1-S) × rotor input

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The low power factor of induction motor is due to

All of these

The reactive lagging magnetizing current necessary to generate the magnetic flux

Stator reactance

Rotor leakage reactance

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An induction motor is preferred to a dc motor because it _______

Provides high starting torque

None of the listed here

Provides fine speed control

Has simple and rugged construction

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The rotor winding of a 3phase wound rotor induction motor is generally _______ connected.

None of the listed here

Delta

Star

Partly star and partly delta

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