Abstract
SF6 has been extensively deployed in high voltage gas insulated equipment to be used as a dielectric medium since 1960 because of its excellent dielectric strength and arc interruption performance. This research proposes promising substitute of SF6, by investigating a refrigerant gas such as Chlorodifluoromethane (CHClF2) with a mixture of CO2/N-2/Air to mitigate environmental hazards of SF6. R-22 has less atmospheric life and low cost as compared to SF6. It has less GWP (1,810) as compared to SF6 (23,900). In this research, the AC and DC breakdown properties of R-22 mixtures along with varying ratios of CO2, N-2,N- and Air were investigated. The best alternative to SF6 has been found to be a mixture of R-22 + N-2 which is close to 81% of SF6 dielectric strength. The dielectric strength of different optimal mixtures was found in the order of SF6 > R-22 + N-2 > R-22 + Air > R-22 + CO2 under AC voltage at 0.4 MPa. Moreover, the boiling point and GWP were further reduced by adding the buffer gases such as N-2,N-, CO2, and Air. R-22 also has acceptable insulation self-recoverability and liquefaction temperature. The results of this study are promising in terms of low cost and environment-friendly alternative to SF6.