Study on the hydrophobic transfer based on the theory of absorption and cohesion

Room temperature vulcanized (RTV) silicone rubber (SIR) coatings are used increasingly on outdoor HV porcelain and glass insulators and bushings when subjected to heavy pollution. An important property of the RTV-SIR coating is its ability to restore the hydrophobicity of the surface after a layer of contamination has built up on it, and thus continues to suppress the development of leakage current, dry band arcing and flashover. As hydrophobicity is the key to the superior contamination performance outdoor insulation, the present study was undertaken to better understand this phenomena. In this paper, the hydrophobic migrations of RTV SIR coating with the pollution of kieselgur and kaolin were measured. The virgin kieselgur and kaolin and them with hydrophobicity were analyzed using Scanning Electron Microscope. The theory of absorption and cohesion is introduced and applied to explain the mechanisms of hydrophobic transfer.