With the goal of“carbon peak

carbon neutralization”being proposed

SF

6

alternative eco-friendly C

4

F

7

N/CO

2

gas

mixtures have attracted wide attention.In order to explore the decomposition characteristics of C

4

F

7

N/CO

2

/O

2

gas mixtures with different micro-aerobic and air pressure under suspended discharge

a series of gas decomposition experiments were carried out.The decomposition products were qualitatively and quantitatively analyzed by GC–MS and GC–PDHID.The results show that

when the oxygen volume fraction is 0%～10%and the air pressure is 0.25～0.65 MPa

the main products are CF

4

C

2

F

6

C

3

F

6

C

3

F

8

CNCN and CF

3

CN.With the increase of oxygen volume fraction

the main decomposition products show a variation trend of“U”type.The decomposition inhibitory effect is most obvious with the oxygen volume fraction of 4%.The decomposition products of C

4

F

7

N/CO

2

/O

2

gas mixtures are negatively correlated with the air pressure

and large molecules such as C

3

F

6

and C

3

F

8

are more difficult to produce at high air pressure than small molecules such as CF

4

and C

2

F

6

.The C

3

F

6

/C

3

F

8

ratio in the absence of oxygen and the C

2

F

6

/C

3

F

6

ratio at 0.25 MPa remains basically unchanged

which is suitable for suspended discharge recognition in these two cases.When using component analysis methods for fault diagnosis of suspended discharge

the influence of oxygen volume fraction and air pressure must be considered and corrected.