Inclined plane tracking and erosion evaluation of filled and unfilled silicone rubber

Filler materials like alumina trihydrate (ATH) and silica are added to silicone rubber to improve their thermal resistance to heat that is dissipated during dry band arcing. In addition, the incorporation of these fillers into a rubber formulation lowers the cost of these compositions making it an attractive choice for manufacturers of outdoor insulation. Although various laboratory tests have shown that fillers are beneficial in preventing tracking or erosion, studies have not demonstrated which of the two materials perform better in actual field applications. Furthermore, some recent studies have shown that the presence of ATH is really not required to enhance the resistance to tracking and erosion. The aim of the present study is to compare the performance of filled and unfilled silicone rubber using the inclined plane tracking and erosion test. Material samples, prepared with either silica or alumina trihydrate are tested while a data acquisition system monitors the voltage and leakage current. The loss of material due to erosion is determined and correlated with the energy of dry-band arcing discharges.