Surface Discharge Characteristics and Numerical Simulation in C4F7N/CO2 Mixture

The environmentally friendly gas C4F7N has been considered a potential replacement gas for SF6 due to its excellent insulation. At present, research on C4F7N and its mixture mainly focuses on its insulation performance, but few people study its surface discharge mechanism and variation law. In order to study the surface discharge characteristics of the C4F7N/CO2 mixture, a fluid model of surface discharge was established and simulated by COMSOL, which was used to study the mechanism of streamers during surface discharge, fit the expression of the maximum photon flux, analyze the influence of voltage and the dielectric constant of the insulator on discharge, and compare the surface discharge of C4F7N/CO2 with that of SF6, providing the theoretical basis for the optical detection and reliable diagnosis of partial discharge. The results show that, under the same discharge conditions, the optical phenomenon of C4F7N/CO2 discharge along the surface is more obvious than that of SF6, and as the applied voltage or the dielectric constant of the insulator increases, the streamer develops more quickly, the electric field becomes stronger, and the photon flux increases.