Comparative Study on the Effect of Inorganic Filler Content and Surface Contaminants on Hydrophobicity Transfer of HTV Polymeric Insulators

One of the main properties of silicones for being used as insulating materials for high voltage overhead lines insulators is hydrophobicity which prevents surface conduction or flashovers on the surface under wet and polluted conditions. Hydrophobicity can be lost during service due to pollutants deposition and material ageing. However, silicone materials have the unique property of recovering hydrophobicity even for polluted surfaces by means of transferring their hydrophobicity to the polluted layer.The aim of this study is to propose a measurement procedure to characterize hydrophobicity transfer and its application to quality assurance. Experimental results of various tests (FTIR spectra, TGA and static contact angle) conducted on different types of new silicones belonging to insulators from various manufacturers are carried out to show their differences. Then, the hydrophobicity transfer capability test has been performed by measuring the static contact angle vs. time after contamination of silicone surfaces using three different pollutants: silicon dioxide at nano and micro size; and saline solution of sodium chloride. It was shown that discrimination of material’s behavior was easier with nano silica particles.