Fractal analysis of nano-reinforced silicone rubber insulators evaluated on a tracking wheel

The increased use of polymer insulators on the overhead electrical power system has led to many designs of insulators, with many profiles and materials, but the performance has not always been stellar, particularly in polluted and wet environments, and degradation by tracking and/or erosion has been the main reason for this. In tests, such as the tracking wheel, visual inspection of tracking and erosion is subjective and can be misleading in establishing a quantitative measure of the damage to insulators. In this article fractal analysis is used to analyze the leakage current that develops on polymer insulators when subjected to pollution and electrical stress. Leakage current manifests itself by dry-band arcing leading to erosion and possible tracking of the polymeric material. Leakage current obtained from continuous monitoring of insulators under test is subjected to a methodology based on fractal analysis.