DC Surface Flashover Performance of Epoxy Composites in C₅F₁₀O/CO₂ Eco-Friendly Gas

The applications of SF 6 alternatives in advanced electrical equipment face many challenges from the perspectives of insulation, decomposition, arc quenching, compatibility, and biosafety. Surface flashover, which is strongly affected by gas properties, is a basic insulation problem for most equipment, but its performance has not been investigated in Perfluoropentanone (C 5 F 10 O) until now. In this work, DC flashover performances of epoxy nanocomposites in C 5 F 10 O mixing gas are first investigated, and the applicability of C 5 F 10 O is discussed. The experiment results indicate surface flashover voltage in C 5 F 10 O/ carbon dioxide (CO 2 ) is 20% lower than pure SF6 when the content of C 5 F 10 O is 20%, but significantly higher than the SF 6 /CO 2 with the same mixing ratio, it indicates C 5 F 10 O mixing gas is potential insulation gas to replace SF 6 . Then, the effects of gas and solid properties on surface flashover in C 5 F 10 O/CO 2 are discussed using density functional theory. It is founded that surface flashover voltage is dominated by positive surface area and average static electronic polarization of gas molecules which determines the electron attachment process in the plasma propagation process. On the other hand, the incorporation of nanoparticles connects EP molecular chains and introduces large amounts of deep traps into the matrix. The enhanced deep trap level and density impede the surface charge injection from the cathode, reducing surface charge accumulation and electric field distribution and finally improving surface flashover voltage.