Comparison of SF/sub 6//N/sub 2/ and SF/sub 6//CO/sub 2/ gas mixtures based on the figure-of-merit concept

Abstract

The dielectric strengths of SF/sub 6//N/sub 2/ and SF/sub 6//CO/sub 2/ gas mixtures, both with a mixing ratio of 50/50, were measured in a plane-parallel gap with a spherical protrusion on the high-voltage electrode surface, and in a gas-impregnated film insulation system with a mid-dielectric void. In both instances the dielectric strength of SF/sub 6//CO/sub 2/ was higher than that of SF/sub 6//N/sub 2/, in contrast to a uniform or quasi-uniform field gap at atmospheric pressure where SF/sub 6//N/sub 2/ is superior to SF/sub 6//CO/sub 2/. The experimental results were in good agreement with calculations using the figure-of-merit values for these two gas mixtures.<>