Erosion of ATH and silica filled silicone rubber in the DC inclined plane test

In this paper erosion of silicone rubber loaded with 30 wt% ATH and silica is investigated in the DC inclined plane tracking/erosion test as per ASTM D 2303. Reduced equivalent DC voltages have been applied in order to compare with the erosion under AC. Hot spot temperatures are used for comparative analysis of dry-band arcing severity on the tested materials. Also, depending on the type of filler, initiation of stable and intense dry-band arcing is discussed. Based on the results it is proposed that the existing material formulation used for AC insulators are not suitable for DC insulators as the erosion is more severe and different.