Suppression of silicone rubber erosion by alumina trihydrate and silica fillers from dry-band arcing under DC

This paper describes the suppression of dry-band arcing erosion of silicone rubber by alumina tri-hydrate and silica fillers in the DC inclined plane test, employing the wavelet based multiresolution analysis of leakage current. The third detail component of the leakage current as decomposed by the wavelet-based multiresolution analysis is shown to be an indicator of the effectiveness of the filler type in suppressing erosion by dry-band arcing. The addition of alumina tri-hydrate or silica filler to silicone rubber increases the thermal conductivity of the composites, retarding the development of the eroding temperature, and thus the evolution of the third detail. Additional effect is also obtained for the dehydration enthalpy, of alumina tri-hydrate in silicone rubber at a filler level of 30 wt%, in impeding the development of hot spots on the tested surface. A reduction in the magnitude of the third detail is evident with filler level, indicating that the increasing volume of silica or alumina tri-hydrate reduces the temperature of the dry-band arcing plasma. Comparable levels of the leakage current third detail is found between 30 wt% alumina tri-hydrate and silica filled composites which suggests the water of hydration plays a minor role in diluting the SiR but at 58 wt% an internal oxidation mechanism that produces gases diluting the arcing phase appears to suppress erosion.