Experience with the CEA generator insulation partial discharge test

This paper briefly describes a partial discharge test for hydraulic generator stator windings which can be done by station staff, without interrupting the operation of the generator. Examples of test results culled from thousands of tests over the past seven years are presented. Aside from pin-pointing machines requiring attention, evidence suggests that this test may be able to identify specific modes of degradation. Partial discharge testing is one of the main reasons Ontario Hydro has a very low winding replacement/major repair rate.