Degradation analysis of RTV-SiR based composites under both polarities DC voltage for insulators coating

In a high voltage transmission system, insulator pollution highly affects the reliability of operation. Air pollutants from surrounding environment accumulated on insulator surface after some time during field operation. Which ultimately polluted the insulators and severely affects their performance in high voltage lines. To combat the pollution effects, high voltage ceramic insulators are coated with room temperature vulcanized silicone rubber (RTV-SiR) as a one-time interminable solution these days. In this study, an attempt has been made to investigate the aging behavior of several composite coatings. Different test samples for coating with various loading concentrations of alumina tri-hydrate (ATH) and silica (SiO2) were fabricated and subjected to multi-stress aging under both polarities of DC voltage. A weather cycle representing a heavily polluted region of Pakistan was simulated in a chamber for 10,000 h. Various diagnostic techniques of aging like hydrophobicity assessment, leakage current monitoring, Fourier transform infrared spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) were utilized. The aging effect on investigated composites was also evaluated through measurements of mechanical properties. Considering the cumulative effect on aging detected through the measurement of several relevant parameters, it has been established that hybrid composite is most resistant to aging. Further, the polarity effect on aging was manifested showing positive polarity as having a more adverse effect on aging as compared to negative polarity.