摘要：Due to its high greenhouse effect, the use of SF<sub>6</sub> as the main insulating gas is restricted in the electric power field. Along with the aim of environmental protection, the search for new alternative gases with a lower greenhouse effect and higher insulation strength has received a lot of attention. The properties of alternative gases have a vital impact on the performance of medium-voltage power distribution equipment. Firstly, based on the existing liquefaction temperatures of SF<sub>6</sub>/N<sub>2</sub>, SF<sub>6</sub>/CO<sub>2</sub>, and SF<sub>6</sub>/CF<sub>4</sub>, the calculated liquefaction temperatures were expanded to 0.7 MPa. Combining the Antoine vapor-pressure equation and the basic law of vapor–liquid balance, the vapor pressures of SF<sub>6</sub>/N<sub>2</sub>, CF<sub>3</sub>I/N<sub>2</sub>, c-C<sub>4</sub>F<sub>8</sub>/N<sub>2</sub>, C4-PFN/N<sub>2</sub>, C4-PFN/CO<sub>2</sub>, and C5-PFK/CO<sub>2</sub> were obtained. Secondly, the critical breakdown field strength was analyzed for C4-PFN/CO<sub>2</sub>, C5-PFK/CO<sub>2</sub>, SF<sub>6</sub>, CF<sub>3</sub>I/N<sub>2</sub>, C5-PFK/Air, and c-C<sub>4</sub>F<sub>8</sub>/N<sub>2</sub>. Finally, the GWPs of SF<sub>6</sub>/N<sub>2</sub>, C4-PFN/N<sub>2</sub>, C4-PFN/CO<sub>2</sub>, C5-PFK/CO<sub>2</sub>, and C5-PFK/N<sub>2</sub> were discussed. The results show that the liquefaction temperature gradually decreases as the pressure rises; SF<sub>6</sub>/N<sub>2</sub> has the highest vapor pressure at −5 °C; the critical breakdown field strengths of several mixtures are higher than that of SF<sub>6</sub>.
