An ideal cooling system for pumped-storage electric machines

The pumped-storage sets have been broadly applied for the power net recently. Due to their changeable load feature, there are some problems of the reliability caused by the temperature difference between the stator core and frame and the thermal expansion difference between the conductors and isolation. Authors propose that the evaporation cooling system (ECS), as an ideal cooling system for the pumped-storage machines and large vertical hydro-generators, can be used not only for new machines but also for upgrading of the existed machines in order to improve the operation reliability without any complexity of maintenance. The results of 3D FEM thermal field analysis for a 400 MW hydro-generator with ECS have been introduced in this paper briefly and the advantages of the ECS have been proved.