THREE PHASE INDUCTION MOTORS QUIZ

In a 3 phase induction motor, the rotor speed is _____ the synchronous speed.

Equal to

Greater than

None of the listed here

Smaller than

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

Greater mechanical strength

Less rotor losses

Uniform torque

None of the listed here

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The number of slip rings on a squirrel cage induction motor is usually

Three

Two

None

One

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

Decreasing rotor resistance

Increasing rotor resistance

None of the listed here

Increasing rotor reactance

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

Less than

About the same

None of the listed here

More than

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The shaft of induction motor is made of

Hollow

Any of the listed here

Flexible

Stiff

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If a 3 phase induction motor is running at a slip S, then approximate efficiency of the motor is ______

1-S

S-1

None of the listed here

1+S

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Insertion of resistance in the rotor of an induction motor to develop a given torque

Increases the rotor current

Rotor current remains same

Rotor current becomes zero

Decreases the rotor current

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The condition of induction motor at stand still resemble those of a transformer whose secondady is _______

Short circuited

None of the listed here

Supplying a variable resistive load

Open circuited

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One of the speeds of a 2 speed squirrel cage induction motor is 800 rpm. The other speed will be _____

2400 rpm

1200 rpm

400 rpm

1600 rpm

TRUE ANSWER : ?
YOUR ANSWER : ?

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