Application of hydrophobic coating to reduce leakage current through surface energy control of high voltage insulator

Abstract A hydrophobic coating was applied using atmospheric-pressure plasma to solve the problem of leakage current caused by the attachment of pollutants to transmission line ceramic insulators. After applying coatings on quartz and ceramic substrates using HMDS:N, C4F8, anti-fingerprint, and CH4 materials, hydrophobicity was determined through water contact angle analysis. In the case of ceramic substrates, the AFM analysis results show that the value of roughness, Ra, determined by the contact angle according to Wenzel's law, of the surface was 63.1–76.4 nm. As a result of XPS and FT-IR analyses, hydrophobic characteristics were observed when C-H bonding was large and Si-O bonding and oxygen content were small. The finite element method analysis shows that when a hydrophobic coating material possessing a high contact angle is used, the adhesion density of contaminants with conductivity is lower than that of a ceramic insulator with hydrophilicity. This reduces the leakage current. It is difficult to artificially clean an insulator in the installation environment, and fewer pollutants will attach to a hydrophobic surface because of rain, snow, or wind in the natural environment.