The usual application of the GGP relay is to prevent motoring of a turbine-driven generator. Its intended purpose is to protect turbines not equipped with integral protective means if its steam supply is lost or reduced. Under such a condition the generator will take power from the bus and run light as a synchronous motor, driving the turbine at normal speed. With insufficient or no steam present in the turbine, the blades may be damaged by overheating as developed by windage. Under normal operating conditions, such heat is dissipated into the steam.