Effects of thermal conductivity on dc resistance to erosion of silicone rubber/BN nanocomposites

Silicone rubber (SiR) is widely employed as an insulating material in transmission lines because of its excellent electrical properties and superior performance under wet and polluted conditions. However, the discharges that occur during operation can cause electrical erosion on the surface of silicone rubber insulators. The thermal conductivity of insulators has a correlation with the resistance to tracking and erosion. This study attempts to clarify whether the addition of boron nitride (BN) particles can improve the resistance to tracking and erosion of SiR by increasing its thermal conductivity. Before the tests, specimens were prepared by dispersing nano-BN particles into room temperature vulcanizing (RTV) silicone rubber at different loadings. In this paper, the dc test has been developed from the current IEC 60587 inclined plane tracking and erosion test to compare the phenomena occurring during the tests. Temperature distribution was observed by an infrared thermal imager. The experimental results indicate that the filled specimens have a lower degree of surface damage than the unfilled specimens. In addition, with the increase in content of fillers from 0 to 7 wt%, the thermal dissipation is improved and both the erosion depth and the weight loss show a decreasing trend, which proves the resistance of silicone rubber to tracking and erosion is improved.