Prime
mover is the device that drives the generator.
Explanation:
Prime mover is the device which provides mechanical energy and
generator is the machine which uses this mechanical energy to
provide electrical energy. Prime mover rotates the shaft of
generator, which in turn produce magnetic flux in the core of
generator. This magnetic flux produces induced voltage. In machines
electrical motor act as a prime mover.
Ex: Some of the prime movers are TURBINES.