Flashover characteristics of artificial polluted UHV AC bushing insulators

Ultra High Voltage (UHV) transmission system will be the key power network of Chinese power grid in the future. The appropriate external insulation design of insulators for different contamination area is one of the most important guarantees for security and stability. In order to give some technical references for insulation design of UHV bushing insulator, artificial pollution tests have been carried out for UHV bushing insulator in the laboratory of State Grid and some flashover characteristics have been obtained in the paper. The experimental results shown that the maximum pollution withstand voltage U_max are affected by equivalent salt deposit density p_ESDD, and the correction formulas of the maximum pollution withstand voltage are pointed out. In addition, the relationship between the 50% pollution flashover voltage U5₀ and the diameter of bushing insulators have been analyzed, the results shown that the 50% pollution flashover voltage is also affected by the diameter of bushing insulator, at the same pollution level, the flashover voltage of small diameter insulator is higher than large diameter insulator. The diameter correction factor K _D of large diameter bushing insulator was given based on test results. Finally, according to test conclusion and design experience about external insulation of bushing insulators, the paper give some dimension parameters of UHV AC bushing insulators for contamination insulation design.