THREE PHASE INDUCTION MOTORS QUIZ

If the air gap between the rotor and stator of a 3-phase induction motor is increased, then_______

Leakage reactances are increased

No load current is decreased

None of the listed here

Leakage reactances are decreased

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

1200 rpm

1600 rpm

2400 rpm

400 rpm

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In an induction motor, the ratio of rotor cu loss and rotor input is given by

S

1/S

S/1-S

1-S

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The starting torque of a squirrel cage induction motor is

Low

Same as full load torque

Slightly more than full load torque

Negligible

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In an induction motor the relationship between stator slots and rotor slots is that

Stator slots are equal to rotor slots

Stator slots are exact multiple of rotor slots

Stator slots are not exact multiple of rotor slots

None of the listed here

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The torque developed by a 3 phase induction motor least depends on

Rotor current

Shaft diameter

Rotor emf

Rotor power factor

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At no load the rotor core loss of a 3 phase induction motor is

None of the listed here

Large

Practically zero

Small

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The speed of a squirrel-cage induction motor can be controlled by all of the following except

Changing supply frequency

Reducing supply voltage

Changing number of poles

Changing winding resistance

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When a 3-phase induction motor is at no load, the slip is ______

0.5

Practically zero

0.2

1

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In medium sized induction motor, the slip is generally around

0.04 %

0.4 %

4 %

14%

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