Study on discharge decomposition characteristics of environmentally friendly gas C6F12O/CO2

Abstract

Recently, finding a new environmentally insulating medium which can replace SF6 has become a research hotspot in the power industry field in recent years. Current research shows that C6F12O has good environmental performance and dielectric strength. In order to further explore the potential of C6F12O/CO2 mixed gas used in medium and low-voltage level electrical equipment, this paper has explored its decomposition characteristics through theoretical calculations and power frequency breakdown tests. First, the formation process of C6F12O decomposition products is calculated by using density functional theory. Then, the decomposition products of C6F12O/CO2 gas mixture with 6% C6F12O was detected by GC-MS after 50 times power frequency breakdown tests. Theoretical calculations show that the C–C bond and C–F bond in the C6F12O molecule are broken to form free radicals CF3•, C2F5•, C3F7• and F atoms, and then they further combine to form fluorocarbon compounds CF4, C2F6, C3F8, C3F6 and C5F12. Among them, the reactions of forming CF4, C2F6 and C3F8 are easier to occur. In the temperature range of 0–1000 K, with the temperature rising, the energy of the main decomposition products does not change much. At the same time, the experimental results show that the breakdown voltage of C6F12O/CO2 mixed gas with 6% C6F12O is about 1.5 times that of pure CO2 under 0.14 MPa. The components and content of the decomposition products are consistent with the theoretical calculation results. The above conclusions can provide theoretical basis and engineering guidance for the application of C6F12O/CO2 mixed gas.