ELECTRICAL MACHINES QUIZ

In travelling cranes for swing action which motor is preferred?

AC slip ring IM.

DC series motor.

Capacitor type induction motors.

Reluctance motor.

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For the purpose of starting an induction motor, star/delta switch is an equivalent to auto transformer of ratio

57.7%

50%

33.3%

66.3%

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In a loaded DC generator, if the brushes are given a shift from the interpolar axis in the direction of rotation, then the commutation will

deteriorate with fall of terminal voltage.

improve with rise in terminal voltage.

deteriorate with rise in terminal voltage.

improve with fall of terminal voltage.

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In escalator which motor is used?

DC shunt motor.

1 - φ IM.

Universal motor.

3 - φ IM.

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A 3 - ÃŽÂ¦ slip ring motor has

double cage rotor.

wound rotor.

any of the above.

short-circuited rotor.

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Tertiary winding in a transformer is mostly

zig - zag star connected.

delta connected.

zig - zag delta connected.

star connected.

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Total core loss is also called as -------------?

Hysteresis loss

Copper loss

Magnetic loss

Eddy current loss

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In a transformer maximum flux density is not constant, the eddy current loss varies as

V

V²

f²

f

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A synchorous generator connected to an infinite bus is over excited. Considering only the reactive power from the point view of the system the machine acts as

None of these.

an inductor.

A capacitor.

A resistor.

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Maximum power developed in a cylindrical synchronous machine depends on

excitation

load angle

synchronous reactance

both 1and 2

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