THREE PHASE INDUCTION MOTORS QUIZ

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

Directly proportional to rotor resistance

None of the listed here

inversely proportional to rotor reactance at standstill

Inveresly proportional to supply voltage

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YOUR ANSWER : ?

DOL starting of induction motors is usually restricted to

High horsepower motors

High speed motors

Variable speed motors

Low horsepower motors

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An induction motor is

Self starting with high torque

Self starting with low torque

Self starting with zero torque

Non self starting

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The low power factor of induction motor is due to

Stator reactance

All of these

Rotor leakage reactance

The reactive lagging magnetizing current necessary to generate the magnetic flux

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The shape of the torque/slip curve of induction motor is

Rectangular parabola

Straight line

Parabola

Hyperbola

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If the frequency of 3-phase supply to the stator of a 3-phase induction motor is increased, then synchronous speed ______

Is decreased

Remains unchanged

Is increased

None of the listed here

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The air gap between stator and rotor of 3-phase induction motor ranges from ______

4 cm to 6 cm

0.4 mm to 4 mm

2 cm to 4 cm

1 cm to 2 cm

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The maximum torque in an induction motor depends on

Rotor inductive reactance

Square of supply voltage

All of the listed here

Frequency

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

None of the listed here

1-S

S-1

1+S

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If the rotor slots are made deeper, rotor resistance is ______

None of the listed here

Increased at starting

Increased under running conditions

Decreased at starting

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YOUR ANSWER : ?

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