Study on AC Pollution Flashover Performance of Bushing External Insulation at High Altitude

Based on the solid-layer and up-and-down methods, the AC pollution flashover tests are carried out on the bushing external insulation in the artificial climate chamber. The altitudes and pollution degrees of those tests are: at different altitudes (232m, 2000 m, 4000 m) and different pollution degrees (ESDD(equivalent salt deposit density) / NSDD(non-soluble deposit density) is 0.05/0.5, 0.1/0.5 and 0.15/0.5 mg/cm
²
). The experimental procedure involves measuring the voltage across a divider during AC pollution flashover events and capturing the arc discharge path with a high-speed camera. The experimental data reveal that the bushing external insulation is more susceptible to AC pollution flashover as the altitude and pollution degree increase. The discharge performance of the bushing external insulation at different altitudes and pollution degrees is summarized, which provides guidance and a basis for selecting the bushing external insulation of the UHV AC substation. Finally, combined with the AC pollution flashover performance of the bushing external insulation at different altitudes, the optimization direction of the bushing external insulation is proposed to improve the reliability of the bushing during operation.