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

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Electrical Machines
An inverted V curve of synchronous motor shows variation of

 supply voltage and excitation current at constant load.
  power factor and DC excitation at constant load.
 supply voltage and field current at constant excitation.
 power factor and supply voltage during hunting.

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Electrical Machines
The damper windings also called the squirrel cage windings or damper grids

  both (A) and (B).
  are provided on the stator for improving power factor.
  consists of short-circuited copper bars embedded in the field pole faces.
  are provided in a synchronous motor to make it self starting.

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Electrical Machines
What will happen if the the supply terminals are reversed in case of a DC shunt motor?

 The motor will run at its normal speed in the same direction as before.
 The motor will run in reverse direction.
 The motor will stop.
 The motor will run much faster in the same direction.

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