Significance of Air Cooled System Over a Gas Cooled System in Large Rotating Electrical Machines

Short circuit generators are used to deliver the short circuit power in testing laboratories. During operation at the time of field excitation a large amount of heat is generated. The dissipation of this heat has to be evacuated to improve the generator efficiency and its reliability. The generator cooling goals are to minimize drag or Windage loss, keep generator internals clean, minimize electrical, mechanical and corrosion problems, and maximize generator output

The purpose of the cooling is to dissipate generator thermal losses by forced circulation of coolant, may be gas, water or air in a closed circuit through the different parts of the generator. This paper explains the methodologies adopted to cool down the electrical machines like generators and to provide the safe working atmosphere to the personnel’s working around it and also emphasizes on challenges to handle the gas cooling system compared to the normal air cooling system. In this paper the actual cooling system is also addressed, used in 1500 MVA Short Circuit Generator.