SF

6

gas is widely used in medium voltage gas insulated ring net cabinets due to its high dielectric strength and strong arc extinguishing capacity. However

SF

6

gas has a high greenhouse effect. In order to reduce the use of SF

6

gas

it is a very important research content to adopt environmentally friendly mixed gas to achieve the similar insulation and arc extinguishing performance with SF

6

while meeting the requirements of high-voltage apparatus in terms of reliability and miniaturization. In this paper

the compressed-air load switch is used to set up a breaking experiment platform. According to the requirements of GB/T 3804—2017 standard for active load breaking

the breaking experiments are carried out on the experimental platform for the mixed gas of 20% C

4

F

7

N+80% CO

2

12% C

4

F

7

N+8%O

2

+80%CO

2

and different opening speeds. The breaking performances of the two mixed gases are analyzed based on the experimental results. After the breaking experiment

it is found that the black solid decomposition products are produced by the arc combustion in the C

4

F

7

N/CO2 gas mixture. The decomposition products are detected and analyzedbyX-raydiffractionmethod

and their composition and conductivity are verified.