Image analysis on the surface hydrophobicity of polluted silicone rubber insulators

Although the spray method (HC method) is a very useful means for periodically evaluating the hydorphobicity of silicone rubber insulators operated in polluted area, it is extremely depends on human subjective judgment. The development of the digital image recording and analyzing technology provides the approach to objective identify the HC levels. However, the criteria of the traditional spray method can not be directly used, because the parameter receding-contact-angle described in the criteria can not be measured in the digital images. This paper presents new criteria based on two simple geometrical parameters for identifying the HC levels of polluted SIR insulators by using the digital image analyzing technology.