Research about Insulation Characteristic of SF6/CO2/N2 and CF3I/CO2/N2 Gas Mixtures at Different Proportions

Abstract

SF6 gas has good insulation performance, but it has been gradually restricted to use because its strong greenhouse effect. In recent years, the search for alternative gases of SF6 has become a research hotspot of scholars. The ionization and attachment coefficients in SF6/CO2/N2 and CF3I/CO2/N2 gas mixtures with different proportions were calculated by the Boltzmann equation, the relationship between critical breakdown field strength (E/N)lim and mixing ratio was also obtained. The AC breakdown characteristics of SF6/CO2/N2 and CF3I/CO2/N2 gas mixtures under 0.1 MPa and uniform electric field were studied experimentally. The results showed that the critical breakdown field strength and AC breakdown voltage of SF6/CO2/N2 and CF3I/CO2/N2 gas mixtures both decreased with the increase of CO2 content. The critical breakdown strength and AC breakdown voltage of SF6/CO2/N2 gas mixtures was always higher than that of CF3I/CO2/N2 gas mixtures at the same ratio, but the gap between them decreased with the increase of CO2 content.