Decomposition products and formation path of C3F7CN/CO2 mixture with suspended discharge

A mixture of perfluoronitrile (C
₃
F
₇
CN) and carbon dioxide (CO
₂
) has excellent insulation and environmental protection properties, and it is considered to have the potential to replace SF
₆
gas. However, there are few studies on the decomposition products and formation reasons of C
₃
F
₇
CN/CO
₂
gas under partial discharge. In order to study the decomposition characteristics of C
₃
F
₇
CN/CO
₂
gas, suspension potential was used to simulate partial discharge. The experimental study on partial discharge decomposition of C
₃
F
₇
CN/CO
₂
gas was carried out. The variation of decomposition products with discharge time was qualitatively and quantitatively analyzed by gas chromatography-mass spectrometry (GC/MS). The results show that the decomposition products of suspension discharge of C
₃
F
₇
CN/CO
₂
are mainly CF
₄
, C
₂
F
₆
, C
₃
F
₈
, CF
₃
CN and an unknown product. The relative contents of C
₂
F
₆
remain basically unchanged with the increase of discharge time. The relative contents of CF
₄
, C
₃
F
₈
and unknown products show a non-linear growth trend with the increase of discharge time. The relative content of CF
₃
CN gas shows a saturation trend with the increase of discharge time. Finally, based on density functional theory (DFT), the formation paths of various products are analyzed.