Electrical Machines
A 3-φ alternator has negligible stator resistance. A short circuit test is conducted on this alternator. At a particular speed, a field current of If1 is required to drive the rated armature current. If the speed of the alternator is reduced to half, the field current required to maintain rated armature current

 Would be equal to If1/2.
 Woud be equal to 2If1.
  Cannot be predicted due to insufficient data.
 Would be equal to If1.

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Electrical Machines
No load primary current in a transformer

 leads the applied voltage somewhat less than 90Ã&
 lags behind applied voltage somewhat less than 90Ã
 leads the applied voltage by exactly 90Â&
 lags behind applied voltage by exactly 90Â&am

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Electrical Machines
In large sized DC machines the compensating windings are provided to

  neutralize voltage induced in coil due to fluctuation of l
 reduce eddy current losses by providing local short circuits.
 compensate for the decrease in speed due to increase of load.
None of these

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