Effects of housing material and configuration on long term ageing deterioration of 275-kV class full scale polymeric insulators

Faster and severer erosions were found on HTV (high temperature vulcanized) silicone rubber polymer insulators compared with RTV (room temperature vulcanized) silicone rubber coated porcelain insulators both by our 275-kV full scale accelerated ageing test and outdoor exposure test in spite of having almost the same leakage distances and being tested under the same test conditions. In order to identify the reason for such difference in ageing deterioration between these two kinds of specimens, specifically to identify which difference in housing material or in specimen configuration is more influential on the ageing deterioration of polymeric insulator surface, comparative ageing tests were started among three specimens, the same two HTV silicone rubber polymer insulators with and without RTV silicone rubber coating to see the effect of material between HTV and RTV silicone rubbers, and one RTV silicone rubber coated porcelain long rod insulator string having almost the same leakage distance with the above-mentioned two polymer insulators to see the effect of specimen configuration by comparing with the RTV silicone rubber coated polymer insulator. After 200 cycles of accelerated ageing test of these three kinds of specimens, clear effects of material and specimen configuration on ageing deterioration of polymeric insulator surface could be identified. RTV silicone rubber is more easily eroded compared with HTV silicone rubber, attributable to the less amount of ATH (Alumina Tri-Hydrate). Porcelain long-rod type specimen configuration is much better compared with polymer insulator type from the view point of anti-ageing deterioration, attributable to the less discharge activities around the trunk portions.