Cooling system of a Hydro Generator
The cooling medium is air which is drawn through channels in the stator core and rotor steels. Heat generated by current flowing in the windings must travel via thermal conduction through the electrical insulation and through the surrounding steel to the cooling medium. Cooling system of each generator has a sufficient capacity to operate the generator at the rated output without exceeding specific temperature rise. Air is circulated by fan action of rotor spider, rotor rim and field poles. It is called rim-duct air circulation. Further air circulates through the open parts of stator frame and coolers.