Electrical Machines
In which of the following speed control of DC motor the speed obtained is below than the rated speed?

 Armature circuit resistance control.
 Field resistance control.
 Any of above.
 Armature voltage control.

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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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