Asynchronous three=phase generator for windmill - produces constant power at all rotation speeds above critical level

摘要

Any excess energy is detected by the rotor control circuit, to prevent overheating of the stator windings of the generator (G). The rotor windings are controlled, via slip-rings, by variable resistors (R). The current flowing in one of the rotor windings is fed via the prim. of a current transformer (T1). The sec. of the transformer produces a voltage to earth which is rectified, compared with a reference voltage, amplified and fed to an electromagnetic device which alters the values of the rotor resistors (R). Two of the rotor winding supplies are interrupted, by a relay (S2), if the windmill comes to a standstill. This prevents the generator acting as a motor.