The relatively high liquefaction temperature of SF

6

gas limits its use in cold areas

while adding some CF

4

gas to SF

6

gas is considered as an effective way to deal with the issue.We analyzed the saturated vapor pressure and insulation characteristics of SF

6

/CF

4

mixture

and discussed the feasibility of applying SF

6

/CF

4

mixture to substitute SF

6

gas for cold areas.First

the Antoine constants of SF

6

and CF

4

gases were obtained by the global optimization method.Then the saturated vapor pressures of SF

6

/CF

4

mixtures were determined by combining the Antoine equation and the basic law of vapor liquid equilibrium.Secondly

the critical electric field strengths of SF

6

/CF

4

mixtures were calculated with Boltzmann analysis.Finally

the insulation properties and applications for cold areas of SF

6

/CF

4

mixture were discussed by combining the saturated vapor pressure characteristic and critical electric field strength.The results show that the allowable gas pressure of SF

6

/CF

4

mixture is remarkably higher than that of pure SF

6

gas under a quite low temperature

and then the insulation strength of SF

6

/CF

4

mixture can be superior to that of pure SF

6

gas.At-40 ℃

the saturated vapor pressures of 50%SF

6

/50%CF

4

mixture and SF

6

gas are about 0.64 MPa and 0.35 MPa

respectively

and the critical electric field strengths at corresponding pressures are about 43.5 k V/mm and 31.34 k V/mm.This means that the insulation strength of SF

6

/CF

4

mixture at a mixed ratio of 50%/50% reaches 1.4 times of SF

6

gas

and the SF

6

/CF

4

mixture under a proper mixed ratio and gas pressure can prevent the liquefaction of SF

6

gas in cold areas.