ELECTRICAL MACHINES QUIZ

The speed of stator rotating magnetic field (RMF) with respect to rotor is

Zero

S.Ns

Ns

Nr

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In a synchronous machine, if the field flux axis is ahead of the armature field axis in the direction of rotation, the machine operating is

synchronous generator.

asynchronous generator.

synchronous motor.

asynchronous motor.

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A separately excited DC motor has an armature resistance of 0.5 Ohm. The supply voltage is 250V. Armature current is 20A and the speed of rotation is 1500 rpm. Find the torque developed?

Zero

16.55 Nm

15.28 Nm

15.6 Nm

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On which of the following factor/factors the speed of a DC motor depends upon?

Field flux.

Applied voltage.

All of these.

Armature current.

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No load primary current in a transformer

leads the applied voltage somewhat less than 90Ã&

lags behind applied voltage by exactly 90Ã‚&am

lags behind applied voltage somewhat less than 90Ã

leads the applied voltage by exactly 90Ã‚&

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When pure inductive load is connected to the alternator, what is the effect of armature reaction?

None of these

Cross magnetization

Magnetization

Demagnetization

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In a star - delta starting of an IM

line voltage is 57.7 % of stator voltage.

applied voltage per stator phase is 57.7 % of a line volt

resistance is inserted in the rotor.

reduced voltage is applied to the stator.

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Universal motor have which of the following application?

Lift.

Traction.

Domestic pump.

Food mixer.

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Ideal value of voltage regulation of a device is?

0

a finite negative value

a positive finite value

∞

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The principle of operation of a 3 - ÃŽÂ¦ induction motor is almost similar to that of

repulsion start induction motor.

synchronous motor.

capacitor start induction motor.

transformer with secondary short circuited.

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