Which method is used to restore generator field residual magnetism?

Flashing the fields is the most effective method for restoring generator field residual magnetism. This process involves applying a brief surge of direct current to the field windings of the generator to create a magnetic field. By doing this, the residual magnetism can be reestablished, enabling the generator to produce voltage when started again.

This method is particularly useful for generators that have been inactive for a period or have had their magnetic field diminished due to various factors, such as power outages or maintenance activities. Flashing the fields is commonly recommended in generator operation manuals as a means to ensure reliable performance.

While rotating the generator manually can help generate some magnetic flow, it is generally not a reliable technique for restoring residual magnetism compared to the direct application of current. Replacing the field windings is an extensive and often unnecessary procedure if the issue is simply the lack of magnetism. Increasing the field voltage may not have immediate effects on the magnetism if the field is completely demagnetized; hence, flashing is the optimal method to restore function efficiently.