SF

6

has been widely used in electrical industry due to its excellent electrical capabilities.However

as for the extremely high GWP of SF

6

researchers have done a lot of investigations on SF

6

alternative gases during the last few decades.Unfortunately

all the methods have their own drawbacks and limitations and can not be applied in practical engineerings.In this paper

C

5

F

10

O/CO

2

gas mixtures

with the partial pressure

of C5F10 O to be 20 k Pa and 40 k Pa

and the total pressure varying from 0.1 MPa to 0.5 MPa

were studied as the main object

while SF

6

gas was used as a control.By the study of the AC and lightning impulse performance

the possibility of this gas mixture to replace SF

6

was discussed.The results show that the AC breakdown voltage of 0.2 MPa C

5

F

10

O/CO

2

gas mixtures with the partial pressure of C5F10 O to be 20 k Pa and 40 k Pa are about 61.89% and 81.99% of SF

6

at the same pressure

respectively.The LI 50% breakdown voltage of 0.5 MPa C

5

F

10

O/CO

2

gas mixtures with the partial pressure of C5F10 O to be 40 k Pa is about 88.9%（+） and 89.9%（-） of SF

6

at 0.3 MPa.Thus

by increasing the content of C5F10 O or the total pressure of the gas mixtures

the insulating performance of the gas mixtures can be effectively improved

of which the former is more effective.