What is the primary source of mechanical power needed to turn a generator rotor?

The primary source of mechanical power needed to turn a generator rotor is the prime mover. A prime mover refers to any machine that converts a form of energy into mechanical energy and is typically an engine or turbine that drives the generator. This mechanical power translation is crucial because the rotational motion generated by the prime mover is what initiates the electromagnetic process in the generator, enabling it to produce electricity.

The relationship between the prime mover and the generator is foundational in power generation systems, where the nature of the prime mover—whether it be a steam turbine, gas turbine, or hydro turbine—will directly impact the generator's performance and efficiency. The prime mover provides the initial input of energy that is transformed into electrical energy, making it indispensable in this context.