In the past, the exciter was a small DC generator coupled to the same shaft as the rotor. Therefore, when the rotor rotates this exciter produces the power for the electromagnet. ... This output from the exiter then controls the magnetic field of the rotor to produce a constant voltage output by the generator.

How does flashing a generator work?

Residual magnetism in the generator exciter field allows the generator to build up voltage during start-up. This magnetism is sometimes lost due to shelf time or improper operation, among other reasons. Restoring this residual magnetism is possible and is sometimes referred to as "flashing the exciter field".

How do windings work in a generator?

The rotating magnetic field of the rotor extends outward and cuts through the armature windings embedded in the surrounding stator. As the rotor turns, alternating voltages are induced in the windings because magnetic fields of first one polarity and then the other cut through them.