Influence of Creepage Distance and Pollution Severity on Flashover Voltage and Parallel Discharge Mechanisms in Glass Insulators

Abstract

This study investigates the impact of creepage distance and insulator geometry on the AC flashover voltage (FOV) and parallel-discharge characteristics of flat-glass insulator models under uniform pollution conditions. Experimental tests were conducted using a plane-plane electrode configuration with pollution conductivities ranging from 17 μS/cm to 10 mS/cm. The results demonstrate that increasing the creepage distance consistently elevates the flashover voltage by forming multiple distinct dry bands, thereby increasing overall dielectric resistance. Furthermore, while an increased insulator diameter reduces total surface resistance, it does not lead to a proportional decrease in FOV. High-speed video analysis reveals that this phenomenon is driven by the simultaneous initiation of multiple parallel arcs across a single dry band, resulting in a higher cumulative electrode voltage drop. Finally, a critical effective width of approximately 8 cm was identified as a baseline threshold required for steady partial discharge propagation. These findings offer valuable insights for optimizing the profile design of high-voltage outdoor insulators. Highlights Flashover voltage rises with creepage distance on clean and polluted glass. More dry zones form as creepage distance increases from 5 to 10 cm. Critical discharge length decreases as pollution conductivity increases. An effective width of about 8 cm is required for parallel partial discharges.