THREE PHASE INDUCTION MOTORS QUIZ

The term cogging is associated with

Induction motors

Dc series motors

Compound generators

Three phase transformer

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An induction motor is so called because its operation depends on

Self induction

Eddy currents

Hysteresis

Mutual induction

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The synchronous speed of a 3-phase induction motor having 20 poles and connected to a 50 Hz source is _____

1200 rpm

300 rpm

600 rpm

1000 rpm

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When the rotor of a 3-phase induction motor is blocked, the slip is _____

0.1

0

1

0.5

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The magnetising current drawn by a 3 phase induction motor is about _______ of full load stator current.

15 to 20 %

10 to 15%

30 to 50%

5%

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The crawling in an induction motor is caused by

High loads

Improper design of machine

Low voltage supply

Harmonics developed in the rotor

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Which of the following component is usually fabricated out of silicon steel?

Shaft

None of these

Bearings

Stator core

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In the circle diagram for induction motor, the diameter of the circle represents

Slip

Line voltage

Running torque

Rotor current

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The power factor of an induction motor under no load conditions will be closer to

0.2 leading

Unity

0.2 lagging

0.5 leading

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5 H.P., 50Hz, 3-phase, 440 V, induction motors are available for the following r.p.m. Which motor will be the costliest?

2880 rpm

1000 rpm

1440 rpm

730 rpm

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