Abstract: An alternating current electrical power generating system in which the generator is driven by a prime mover, such as a fluid-driven turbine, whose speed may vary, the generator rotor being coupled to the output shaft of a differential drive unit, one input of which is coupled to the prime mover and the other input of which is coupled to a synchronous generator whose output is fed to a thyristor controlled variable load.

Abstract: An alternating current electrical power generating system in which a generator (11) is driven by a fluid driven turbine (2), whose speed or torque may vary, which incorporates a differential drive unit (3) coupled to the turbine (2), the generator (11) and means, such as a reaction machine (6), arranged to control the torque on the respective input to the differential drive unit in response to changes in the speed of the turbine in the sense which tends to compensate for such speed variations and thereby reduce fluctuations of torque on the generator.