Electrical Machines
For a given torque, reducing divertor resistance of a DC series motor

  Increase in speed demanding more armature current.
  Decrease in speed but armature current remains the same.
  Decrease in speed demanding less armature current.
  Increase in speed but armature currnet remains the same.

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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

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

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