Synergistic Effect of SF6/N2 Gas Mixtures in Slightly Non-uniform Electric Field Under Lightning Impulse

In recent years, SF6/N2 gas mixtures was getting used as insulating medium in many gas-insulated equipment because of the greenhouse effect and poor economy of pure SF6 gas. This paper studied on the synergistic effect of SF6/N2 gas mixtures with low SF6 mixing ratio in slightly non-uniform electric field under positive and negative lightning impulse. The research indicates that the synergistic effect of SF6/N2 gas mixtures breakdown voltage under negative lightning impulse or positive lightning impulse was appeared obviously. The breakdown voltage under negative lightning impulse is higher than which under positive lightning impulse with low SF6 mixing ratio, but when SF6 mixing ratio exceeds a critical value, the breakdown voltage under negative lightning impulse is lower. The…