Electrical Machines
The full load copper loss and iron loss of transformer are 6400W and 5000W respectively. The copper loss and iron loss at half load will be respectively?

 1600 W and 1250 W
 3200 W and 2500 W
 3200 W and 5200 W
 1600 W and 5000 W

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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

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

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Electrical Machines
The synchronous motor can be started by

  any of the above methods.
  coupling it with a DC compound motor.
  coupling it with a small AC induction motor called the pony motor.
  providing damper winding in its rotor circuit.

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