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

ANSWER DOWNLOAD EXAMIANS APP

Electrical Machines
In a star - delta starting of an IM

  line voltage is 57.7 % of stator voltage.
  resistance is inserted in the rotor.
  applied voltage per stator phase is 57.7 % of a line volt
  reduced voltage is applied to the stator.

ANSWER DOWNLOAD EXAMIANS APP