US Patent 7230345 Method for exercising a stand-by electrical generator

A method is provided for exercising an engine-driven, electrical generator. The generator has a first operation mode wherein the generator generates a predetermined output voltage at a predetermined frequency with the engine running a predetermined operating speed and a second exercise mode. The method includes the step of running the engine at a predetermined exercise speed with the generator in the exercise mode. The predetermined exercise speed is in the range of 40% to 70% of the predetermined operating speed of the engine. In addition, in the exercise mode, the generator generates an exercise voltage that is less than the predetermined output voltage.