Breakdown characteristics of oil-polymer composite insulation under AC and DC voltages

The breakdown characteristics of silicone oil-polyethylene composite insulation under ac and dc voltages has been studied using the needle-plane electrode system. Higher breakdown voltages have been observed with LDPE film as a barrier for both polarities, although the effect was more significant under positive polarity. Breakdown voltages under ac voltages were significantly lower than those measured under dc with both polarities; however, breakdown voltages with LDPE film were higher than those with oil alone