Signature analysis of flashover voltage phenomena on contaminated insulator surfaces

This paper discusses some of the physical process involved in the flashover of non-ceramic and ceramic contaminated insulator surfaces. The various discharges and flashover voltage (FOV) phenomena on insulator surfaces (nonceramic vs. ceramic) were investigated by means of slow and fast oscillographic recording of the discharge current. Discharge current signatures were analyzed by means of fast Fourier transform (FFT). It was found that the surface discharges have distinct stages of development for different surfaces (low surface energy vs. high surface energy). The visual manifestations were recorded simultaneously with the current pulses, providing a good correlation and an exact physical interpretation. It was observed that FOV phenomenon is different for non-ceramic and ceramic insulators. The results will be useful for development of improved laboratory test procedures and to evaluate the performance of nonceramic insulators in contaminated conditions