Study and evaluation on comprehensive characteristics of different common fluorides as possible SF6-substitute for power application.

Fluorides and their CO 2 mixtures are considered as promising choices of SF 6 -substitute gases due to their low global warming potentials and high dielectric strength. This paper investigates physical and chemical properties and breakdown characteristics of different common fluorides and their mixtures for application in the power system. For dielectric characteristics of fluorides and their mixtures, their power frequency breakdown voltages are determined experimentally, and the results are compared with SF 6 . For physical and chemical characteristics, the saturated vapor pressures, global warming potentials (GWPs), toxicities, prices of fluorides and their mixtures are calculated, and the corresponding characteristic curves are obtained. Based on characteristics mentioned above, a method for obtaining the optimal gas parameters of a specific fluoride mixture is proposed, which can be used as a feasible solution to find an SF 6 alternative gas that meets the application requirements. The results show that CO 2 mixtures with hexafluoropropene (HFP), 1,1,1,2-tetrafluoroethane (HFC-134a) and perfluoroisobutyronitrile (C4-PFN) are three types of good SF 6 -substitute gases. HFP/CO 2 mixtures with HFP component ratios 0.32 to 0.6 are suitable for applications at 0.1 to 0.3 MPa. HFC-134a/CO 2 mixtures (HFC-134a component ratios from 0.16 to 0.2) are suitable for applications at 0.3 to 0.5 MPa. C4-PFN/CO 2 mixtures (C4-PFN component ratios from 0.09 to 0.12) could be used for the applications at 0.1 to 0.5 MPa, regardless of the gas price. [ABSTRACT FROM AUTHOR]