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

The applications of SF6 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 (C5F10O) until now. In this work, the dc flashover performances of epoxy (EP) nanocomposites in C5F10O mixing gas are first investigated, and the applicability of C5F10O is discussed. The experimental results indicate that surface flashover voltage in C5F10O/carbon dioxide (CO2) is 20% lower than pure SF6 when the content of C5F10O is 20% but significantly higher than the SF6/CO2 with the same mixing ratio, and it indicates that C5F10O mixing gas is potential insulation gas to replace SF6. Then, the effects of gas and solid properties on surface flashover in C5F10O/CO2 are discussed using the density functional theory (DFT). 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.