THREE PHASE INDUCTION MOTORS QUIZ

The maximum torque of a 3-phase induction motor under running conditions is

inversely proportional to rotor reactance at standstill

Directly proportional to rotor resistance

Inveresly proportional to supply voltage

None of the listed here

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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

730 rpm

1440 rpm

1000 rpm

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

Shaft diameter

Rotor emf

Rotor current

Rotor power factor

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The reactance of the rotor circuit of a 3-phase induction motor is maximum at

No load

Starting

Half full load

Full load

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The torque developed in the cage induction motor with auto-starter is

k2/torque with direct switching

K2 Ã— torque with direct switching

K Ã— torque with direct switching

k/torque with direct switching

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Friction and windage loss of a 3 phase induction motor are

Remains the same at all loads

Minimum at no load

None of the listed here

Maximum at no load

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DOL starting of induction motors is usually restricted to

High speed motors

Variable speed motors

High horsepower motors

Low horsepower motors

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The starting torque of a 3-phase induction motor is _______ supply voltage.

Independent of

Directly proportional to

Directly proportional to sqaure of

None of the listed here

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

1

0.2

Practically zero

0.5

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A four speed squirrel cage induction motor uses______ stator windings.

Two

One

Three

Four

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