ELECTRICAL MACHINES QUIZ

Which of the following are variable losses?

shunt field copper loss

eddy current loss

hysteresis loss

armature copper loss

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In an alternator the voltage generated per phase is proportional to

frequency of waveform.

number of turns in coil.

flux per pole.

All of these

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What type of dielectric material is used in capacitors used for fans and for power factor correction?

Vacuum.

Mica.

Glass.

Oil impregnated paper.

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In escalator which motor is used?

Universal motor.

DC shunt motor.

3 - φ IM.

1 - φ IM.

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In a 3 - ÃŽÂ¦ wound rotor induction motor the short circuit gear is used to short circuit the

rotor at slip rings.

None of these

starting resistance in the starter.

stator phases of the motor.

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Which of the following motor is suitable for frequent starting and stoppings?

Resistance split phase motor

Capacitor start capacitor run motor

All of these

Capacitor start motor

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A 4 pole, 3-phase induction motor is running at 4% slip at full load. If the speed of the motor is 720 rpm, the supply frequency is

50 Hz

40 HZ

25 Hz

60 Hz

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The voltage regulation of a DC generator at full load being zero implies that the generator is

deferentially compounded.

series connected.

cumulatively compounded.

shunt connected.

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In double cage induction motor, the inner cage offers

high resistance and high reactance.

low resistance and high reactance.

low resistance and low reactance.

high resistance and low reactance.

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In DC machines, the interpoles are provided

both (B) and (C).

to counteract the reactance voltage and the cross-magnetizi

to counteract demagnetizing effect of armature mmf in commutating zone.

to make commutation spark less.

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