Electrical tree characteristics with the addition of alumina in silicone rubber

The introduction of nano technology gives many benefits to the consumers and industries especially in cable insulators fabrication. This technology offers better cable life time and better cable resistance to face the cable failure. With the inclusion of nano filler in unfilled polymer, it shows that the nano filler has the ability in refining the electrical, mechanical and thermal properties compared to the unfilled polymer. In this paper, nano-alumina with the amount of 0 to 3 vol% was employed to upgrade the electrical tree properties in unfilled silicone rubber (SiR). Electrical treeing inception and propagation in SiR with and without filler were studied. 8kV_rms 50Hz ac voltage was given through the needle electrode to inspect the tree inception voltage and treeing propagation process. This needle electrode was positioned in rectangular mould test specimen. The dimension of the specimen was 20mm × 14mm × 1mm. With the inclusion of nano-alumina in SiR, the results showed that the SiR nanocomposites can delay the occurrences of tree inception, tree growth and electrical breakdown up to 2 vol% which may influence better electrical treeing characteristics. However with 3 vol% nano-alumina, SiR nanocomposites has the fastest treeing growth and eventually breakdown at the time less than 1 minute.