Partial discharge and breakdown mechanisms in ultra-dilute SF6/N-2 gas mixtures

With the goal of reducing SF6 gas usage, we investigated partial discharge (PD) and breakdown (BD)mechanisms in ultra-dilute (0 to 1%) SF6/N-2 gas mix tures. The experimental results and discussions are given in this paper. In particular, we focused our research on the transition characteristics of t he electrical insulation performance with an extremely small amount of SF6 content, the PD behavior an the applied voltage, and the relation among pre breakdown streamer, return stroke and ED. Moreover, we discussed the PD and ED mechanisms with reference of space charge behavior. From these results, the transition threshold at which the influence of SF6 gas on the discharg e characteristics began to appear, was clarified to be SF6 content k=10 ppm for a total pressure of 0.1 MPa.