What is residual Flux in generators?

Residual flux in generators refers to the small amount of magnetic field that remains in the rotor or stator after the generator has been shut down. This residual magnetism is crucial for the initial generation of voltage when the generator is started, as it provides the necessary magnetic field for induction. If the residual flux is too low, the generator may fail to produce voltage until it is externally excited. This phenomenon is especially important in shunt and compound-wound generators.