Research on Pollution Flashover Characteristics of Hydrophilic Surface under Combined AC-DC Voltage

Pollution flashover is one of the major problems for transmission lines. The pollution flashover characteristics under pure AC is greatly different from pure DC. In this paper, the pollution flashover characteristics of hydrophilic surface under combined AC-DC voltage were studied. Flashover voltage of the insulator are mainly influenced by the pollution level. A high voltage test power source with AC-DC compound voltage was designed in this research. The effect of contaminants on flashover performance of glass panels under different types of voltages was studied by artificial pollution test and gap breakdown test. Different ratios of combined AC-DC voltage can be generated by the power source. It has been found that with the change of DC component, the breakdown voltage and flashover voltage vary. One theory is that flashover is mainly a process of electrical breakdown above the pollution layer. It has been found that flashover characteristics may be related to the breakdown characteristics and zero crossing point for voltage.