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

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

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Electrical Machines
A dc shunt generator, when commissioned after a major repair of the field system, failed to build Up voltage. It was because

 field resistance was higher than critical resistance
 field system lost residual magnetism
 field winding was wrongly connected
 there was a break in the armature circuit

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