What could cause voltage buildup on starting to fail to occur? How can this problem be remedied?

Thegenerator is failed to build up for the following reason:-

·         No residual magnetism:  if there is little or no residual magnetism, because of inactivity or jarring in shipment, no voltage will be generated that can produce field current.

·         Field connection reversal: the voltage generated due to residual magnetism is applied to the field and current flow in such a direction as to produce lines of flux in the same direction as the residual flux. If the field connections are reversed, the lines of the flux produced by the current flow will oppose the residual flux so that the generated voltage will decrease rather than increase.

·         Field- circuit resistance too high:  if the field current resistance is greater than the critical voltage. Then this prevents voltage buildup.

·         Dirty commutator:  a dirty commutator does not permit good contact between brushes and the commutator. This poor contact shows up as a high resistance to floe of current in the field circuit.

This problem can be remedied by taking some steps:-

·         A separate source of direct current is applied to the field for a short period of time and then removed.

·         We can reverse the field connection with respect to armature.

·         The value of field resistance can be taken less than critical resistance.

·         We can remove the dirt from the commutator.