Electric field dependence of SF6 nonlinear discharge characteristics: N-curve estimations

Abstract

The N-curve of SF6 describes the relationship between the AC breakdown voltage in an extremely inhomogeneous electric field and pressurized SF6 gas. It is directly dependent on the electric field distribution, which is determined by the gas gap, curvature radius, and background electric field. An increase in gap distance, a decrease in curvature radius, and relatively weak background electric field are all conducive to corona stabilization. The electrode curvature radius is the determining factor in the positive glow corona (PGC) discharge quenching pressure. The breakdown voltage dominated by the streamer mechanism can be estimated accurately by calculating the electric field based on the Deutsch assumption and combining it with the SF6 static field breakdown criterion. The proposed method is applicable to the estimation of N-curves in gaps with varying field distributions. The work presented in this paper may support further quantitative research on the discharge mechanism of strongly electronegative gas dielectrics.