Influence of seasons on hydrophobicity of silicone rubber insulators in semi-wet warm-temperature zone of china

This paper shows a dynamic change of hydrophobicity on the surface of silicone rubber (SIR) insulators with seasons in a semi-wet warm-temperature zone of China based on the data from the dynamic testing in an outdoor test field and the on-line dynamic testing in a 220 kV and three 110 kV transmission lines for over a year. It is found that the surface hydrophobicity of SIR insulators served in the semi-wet warm-temperature zone of China can gradually decrease from HC1-HC3 to HC5-HC7 in winter, and recover to HC1-HC3 in summer. The combination of continuous pollution deposition, low ambient temperature and poor pollution washing by precipitation could be the reason leading to the low surface hydrophobicity of the SIR insulators in winter. It is also found that the pollution layer with the dense micro-structure could block the hydrophobicity transfer from the material to the surface of the pollution layer, resulting in the low surface hydrphobicity of the SIR insulators even in summer. Based on the results, a dynamic inspection method on the surface hydrophobicity of SIR insulators is proposed, in which the surface hydrophobicity decrease in winter and the recovery in summer are considered.