Dielectric characteristic of dichlorodifluoromethane (R12) gas and mixture with ${\rm N}_2$N2/air as an alternative to ${\rm S}{\rm F}_6$SF6 gas

In this study, dichlorodifluoromethane (R12) gas and mixtures with nitrogen (N2) and air at different pressures and mixing ratios have been investigated and showed good alternative to ${\rm S}{\rm F}_6$SF6 gas in terms of high-voltage application. Mixed gases contain R12 gas, they offer good dielectric properties and possibility to be used in low-temperature environment. Synergistic effects and self-recoverability test have been performed. Dielectric strength under quasi-uniform field showed in the order of ${\rm S}{\rm F}_6 \gt {\rm R12} \gt {\rm N}_2 \gt $SF6>R12>N2> air in alternating current (AC), direct current (DC) and impulse was examined. Mixture R12/N2 (80/20%) could reach over 0.90–0.95 times to that of ${\rm S}{\rm F}_6$SF6 gas at 50 lb/in2 at AC and R12/air (70/30%) gives 0.80–0.90 to ${\rm S}{\rm F}_6$SF6 gas. R12 gas presents brilliant self-recoverability. The optimal ratio to switch ${\rm S}{\rm F}_6$SF6 gas is R12/N2 (80/20%) and R12/air (70/30%) is based on the authors’ experimental condition and setup.