Electrical Machines
What is/are the necessary conditions for voltage build up in self excited generator?

 Field winding resistance should be less than critical resistance.
All of these
 Poles should contain residual flux.
 Field winding should be properly connected to armature winding.

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Electrical Machines
In a 3 - Φ induction motor

  power factor at starting in the same as that while running.
  none of them.
  power factor at starting is high as compared to that while running.
  power factor at starting is low as compared to that while running.

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