THREE PHASE INDUCTION MOTORS QUIZ

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

Full load

Starting

No load

Half full load

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The frame of an induction motor is usually made of

Aluminium

Silicon steel

Bronze

Cast iron

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

K2 Ã— torque with direct switching

k/torque with direct switching

K Ã— torque with direct switching

k2/torque with direct switching

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

1

0.5

0

0.1

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The condition of induction motor on load resemble those of a transformer whose secondady is _______

Short circuited

Supplying a variable resistive load

Open circuited

None of the listed here

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The full load slip of a 3-phase induction motor ranges from

20 to 30 %

None of the listed here

10 to 20 %

2 to 5 %

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The cogging of an induction motor can be avoided by

Having number of rotor slots more or less than the number of stator slots

Auto transformer starter

Using DOL starter

Proper ventilation

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In an induction motor if air gap increased

Windage losses will be more

Copper loss will reduce

Bearing friction will reduce

The power factor will be low

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A 3 phase 440 v, 50 Hz induction motor has 4% slip. The frequency of rotor emf will be

50 Hz

200 Hz

20 Hz

2 Hz

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

Rotor emf

Shaft diameter

Rotor power factor

Rotor current

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