Study On The Evaluation Method Of The Hydrophobicity Of Composite Insulators By Using Digital Image Analysis Technology

Periodically evaluating the hydrophobicity of composite insulators in service is necessary for safety of the electric power system. Based on the technology of image analysis,this paper researchs the hydrophobicity of composite insulators, then analyzes the accuracy of evaluation methods for hydrophobicity of composite insulators by experiments. These methods are more depended on subjective judgment, lower accuracy and do not consider the effect of drop's choice, the size and shape of selective area, shooting angle and shooting distance on the hydrophobicity of composite insulators. This paper researches into those problems mentioned above. The result of the experiments determines the method for shooting image, extracting drop and selective area on the basis of image analysis technology, and concludes the modified criteria for hydrophobicity of composite insulators. This modified ctiteria evaluate the hydrophobicity of composite insulators by two levels, the first lever evaluates hydrophobicity or hydrophilicity, the second lever is more detailed. Test proved that the accuracy of first level is 99% and the second is 95.1%. The modified criteria can provide theoretical foundation for development and updating analytic software of the hydrophobicity of composite insulators in the future.