The equivalent dissolved salt deposit density of contamination on surface of silicone rubber

The equivalent salt deposit density (ESDD) is one of the appropriate parameters to describe the level of contamination on the surface of insulator. Because of the unique properties of silicone rubber, some contamination on the surface of silicone rubber is difficult to be dissolved, which is not related to the pollution flashover. This paper proposes the equivalent dissolved salt deposit density (EDSDD) to describe the level of the contamination of the silicone rubber composite insulator. The EDSDD represents the quality of contamination which is dissolved in wetting process on the surface of silicone rubber and The EDSDD is related to the ESDD and the hydrophobicity of silicone rubber. The EDSDD can be arrived from the ESDD and the hydrophobicity of the silicone rubber and a special instrument is designed for measuring the ESDD of silicone rubber at the outdoor. A series of experimental results show that only part of contamination is dissolved in the wetting process and the quantity of contamination dissolved is related to the hydrophobicity of silicone rubber. Only 1/5 contamination is dissolved during the wetting process if the contact angle of the silicone rubber reaches 120 degrees. The dissolution rate of contamination on the surface of silicone rubber is very fast, so the ESDD can be measured by the special instrument quickly.