What are the basic reasons for loss of residual magnetism? How do you get it? What is the requireable and maximum DC voltage is to be applied to get back the residual magnetism?
Ans. The reasons for loss of residual magnetism are taking the alternator in idle condition for long time and connecting field wires in wrong polarity. To get back the residual magnetism flash the field terminals for correct polarity of DC supply. The permissible DC voltage is to be applied to get back the residual magnetism is 6 to 12V DC. Highest voltage is 24V DC.