Calculation of dielectric strength of the SF6/N2 gas mixture in macroscopically and microscopically non-uniform fields

Dielectric strength of the SF₆/N₂ gas mixture in a uniform field can be calculated using a simple method assuming there is no interaction between the different component gas molecules. However, to calculate the dielectric strength of the gas mixture in a practical gas-insulated system, both the electrode curvature factor and the electrode surface roughness factor should be taken into account. This paper presents the electrode curvature factors for SF₆/N₂ in a coaxial electrode system and in a concentric spherical electrode system, and reports the effect of electrode surface roughness on breakdown in the SF₆/N₂ gas mixture