Surface Morphological and Infrared Thermographic Assessment of Natural Ester Oil Aged Silicone Rubber Microcomposites

Room temperature vulcanized (RTV) silicone rubber coatings doped with commercially available alumina trihydrate (ATH) and Silica (SiO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>) micro-fillers, are extensively being utilized in porcelain-based bushings of oil immersed transformers to improve their operational safety and reliability. They are valued for their hydrophobic properties and the ability to transfer this hydrophobicity, anti-flashover and good contamination performance. However, the exposure of RTV silicone rubber composites to transformer oil (next generation natural ester oil) is detrimental and remains largely unexplored. In this context, the present work involves experimental investigations on surface morphology and thermal performance of undoped and doped with 45 weight percentage (wt. %) of ATH and SiO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> silicone rubber microcomposites. These test specimens were thermally aged in transformer natural ester oil at 80°C for 250 hours. Further, the ageing induced the deterioration of surface properties are clearly observed through 3D microscopy which revealed an increase in the surface roughness of all the test specimens. To assess the heat dissipation capability the infrared (IR) thermography was employed. The IR thermographic patterns were captured post ageing in natural ester oil using thermal camera. Also, the heat discharge patterns post water droplet-initiated corona discharge (IEC 60112) were monitored. Finally, in conclusion surface morphology and infrared thermography results have been demonstrated that post ageing in natural ester oil 45 wt. % micro-SiO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> doped RTV silicone rubber test specimen showed better performed than the micro-ATH doped and undoped silicone rubber test specimen, would have promising and suitable for transformer bushing applications.