Investigation on surface flashover characteristics of the insulator with different transformer oil coating conditions in vacuum

The vacuum insulator surface flashover phenomenon unusually occurred in the pulsed power devices. We used the transformer oil to coat on the insulator surface for increasing the insulation strength in vacuum. The experiment results show that the transformer oil coating could significantly improve insulator flashover voltage level due to oil layer limited the development of the secondary electron avalanche. We have changed the transformer oil coated regions to investigate the insulator flashover strength. The experiments indicated that the coating region would influence the flashover voltage. The flashover strength would be improved by coating transformer oil on the cathode region. The design of grooved insulator would increase the flashover strength. The flashover strength of grooved insulator with coating oil is higher that of flat insulator with coating oil.