A study of surface discharges from water droplets on silicone rubber insulators

The objective of the work is to investigate the use of partial discharge (PD) measurements from water droplets as a possible means to study the pre-leakage current development on silicone rubber insulating surfaces. The experimental set-up, which allows PD measurements from water droplets on the insulating surface under controlled atmospheric conditions, is described. An optical system is also used for simultaneous observations of the surface conditions. Experiments with single droplets and water condensation on the insulator surface are reported and the corresponding PD patterns are presented. The study shows that it is possible to detect PD at the very early stage of leakage current development and correlate it to the changes in the field distribution due to water droplets