Effects of algae contamination on the hydrophobicity of high-voltage composite insulators

Abstract

Algae colonisation has been observed on silicone rubber insulators around the world especially in a subtropical climate because the moderate temperature and moisture could aggravate the growth of algae upon silicone rubber material. The surface of these insulators easily forms a water film, and the originally excellent hydrophobicity is decreased or even destroyed. This study explores the regularity of the hydrophobicity changes and the underlying mechanism. Based on the solid layer method, silicone rubber samples were found with algae and inorganics quantitatively, and their contact angles were measured after reservation under different humidity levels. The results showed that although inorganic ash could accelerate the hydrophobic recovery process, algae colonisation decisively decreased the hydrophobicity, especially in moist climates. After an extensive investigation of biological contaminants, it was found that the appearance of algae was independent of inorganics, but algae could accelerate the accumulation of inorganics through water absorptivity and the viscosity of secretions. The water absorption ability of algae was compared with that of inorganic ash and sugar, and their difference was deduced to be due to the environmental adaptability of the algae organisms, which was reflected mainly in a dry climate. The microscopy analysis of bio-contaminants was conducted through SEM.