Synchronous Generator

Synchronous generators require an external DC power supply to be applied to the main rotor windings by means of slip-rings and carbon brushes in order to produce a constant magnetic field basically making the main rotating part (the rotor) of a synchronous machine into a large electromagnet. The rotor is rotated by the external wind turbine blades connected to it creating a rotating magnetic field within the generators body. Electrical copper windings are incased into the stationary part (the stator) of the synchronous generators body and are the main windings where the voltage is induced. So by varying the amount of rotor field current, it is possible to vary the staors output voltage.