Investigations on the partial discharge behavior of syntactic foam under uniform field stress

This paper deals with the partial discharge behavior of epoxy resin filled with hollow glass microspheres. The resulting material, called syntactic foam, is a new composite insulation material which combines advantages of solid and gaseous dielectrics. Specimens of syntactic foam are stressed with uniform AC field stress and the partial discharge activity is simultaneously measured. After the electrical stress the material structure is visualized by Scanning Electron Microscopy. As an essential result of this investigation a theory of the breakdown process of syntactic foam under uniform field stress is developed. Unexpectedly, the breakdown process differs from the one under non-uniform field stress described.