THREE PHASE INDUCTION MOTORS QUIZ

As load on an induction motor goes on increasing

Its power factor goes on decreasing

Its power factor goes on increasing even after full load

Its power factor goes on increasing up to full load and then it falls again

Its power factor remains constant

TRUE ANSWER : ?
YOUR ANSWER : ?

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

None of the listed here

40%

65%

90%

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The crawling in an induction motor is caused by

Harmonics developed in the rotor

Improper design of machine

High loads

Low voltage supply

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If any two phases for an induction motor are interchanged

The motor will not run

The motor will run in reverse direction

The motor will run at reduced speed

The motor will burn

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DOL starting of induction motors is usually restricted to

Variable speed motors

High horsepower motors

High speed motors

Low horsepower motors

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

80 to 90%

95 to 98 %

99%

60 to 90%

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

25 Hz

None of the listed here

50 Hz

60 Hz

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The good power factor of an induction motor can be achieved if the average flux density in the air gap is

Large

Small

Infinity

Absent

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

Less rotor losses

Greater mechanical strength

None of the listed here

Uniform torque

TRUE ANSWER : ?
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In medium sized induction motor, the slip is generally around

14%

4 %

0.04 %

0.4 %

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YOUR ANSWER : ?

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