Influence of conducting particles on the breakdown voltages of SF 6-N2 mixture

The design stress of sulphur hexafluoride (SF₆) gas-insulated switchgear (GIS) systems are limited by the harmful effects resulting from the electrode surface roughness and the almost inevitable presence of particulate contamination in GIS equipment. So, this paper studies the breakdown voltages (BDV) of SF₆-N₂ gas mixture with particles contaminating a parallel plane gap under DC voltage. The effect of particle dimensions on the breakdown voltage is analytically studied in this work. The breakdown voltage-pressure characteristics are deduced. Also, a comparison between the breakdown voltages for SF₆ gas and the SF₆-N₂ gas mixture for the study case are presented. The effect of the fractional concentration of SF₆ in the mixture on the breakdown voltage for this problem is also given