VENTILATION OR COOLING OF AN ALTERNATOR

• The slow speed salient pole alternators are ventilated by the fan action of the salient poles which provide circulating air.

• Cylindrical rotor alternators are usually long, and the problem of air flow requires very special attention.

• The cooling medium, air or hydrogen is cooled by passing over pipes through which cooling water is circulated and ventilation of the alternator.

• Hydrogen is normally used as cooling medium in all the turbine-driven alternators because hydrogen provides better cooling than air and increases the efficiency and decreases the windage losses.

• Liquid cooling is used for the stators of cylindrical rotor generators.