Dynamics of dry-band arcing on silicone rubber in the inclined plane test under AC, +DC and −DC voltages

In this paper a parametric study of the dry-band arcing characteristics in the inclined plane tracking and erosion test is conducted under AC and DC voltages. The standard inclined plane testing apparatus is modified to promote stable and intense dry-band arcing, thereby analyzing the characteristics of the eroding dry-band arcing. The behavior of the liquid contaminant, which may bias the dry-band arcing current under equal AC and DC voltages, is investigated for different flow rates to determine suitable testing conditions. The highest leakage current magnitude is obtained under +DC followed by AC and -DC voltages, and reduced resistivity for the dry-band arcing column is shown under the +DC and AC as compared to the -DC voltages. The reduction in resistivity is speculated to be the result of metallic ions from electrode corrosion under +DC as compared to -DC, with less significant difference between +DC and AC. In addition, the inception behavior of the discharge influencing the length of the dry-band arc is found to be dependent on the voltage type. Reduced dry-band arcing length is measured for DC as compared to AC, with further reduction shown under +DC as compared to -DC. Thermal analysis is accordingly conducted, showing higher hot spot temperatures with dry-band arcing of a shorter length.