Investigation of electrical treeing structures in SiR/Alumina nanocomposites

Electrical tree is the one of phenomena that can initiate to the electrical breakdown in polymeric insulating material. In this paper, the structure of electrical tree growth in Silicone Rubber (SiR) with different concentration of nano-alumina has been observed. The test specimen samples were prepared by mixing SiR base polymer with 0, 0.5, 1, 1.5, 2, 2.5 and 3 vol% of nano-alumina. The structure of electrical tree was investigated at apply voltage of 8kVrms after tree inception voltage under room temperature. The influences of nano-alumina with different concentration to the electrical tree structure were investigated. The result shows high probability occurrence of Bush type tree with the increased of nano-alumina in SiR up to 2 vol%. However, at 3 vol% nano-alumina with slight agglomeration in SiR/Alumina nanocomposites, the tree structure drastically change to Pine Branch type which lead to the fastest tree inception voltage and tree propagation rate.