Corona Deterioration Reduction in Large Electrical Machine Insulation

Partial discharge or corona activity in the insulation system of large electric machine stators has caused deterioration of these machines, and in some cases resulted in premature failures. Development work is being done to better understand the cause and effects of this corona activity. Efforts are centering around the increased use of corona-resistant material, and the reduced use of corona-sensitive materials. Some of the developments are described in this paper.>