Comparative Study on Post-arc Dielectric Breakdown Characteristics of C4F7N and C5F10O Gases Mixed with CO2

C4F7N and C5F10O are considered promising SF6 substitute gases with potential applications. However, current research has predominantly focused on analyzing their insulation performance, with less emphasis on their arc extinguishing capabilities. Therefore, this study aims to investigate the post-arc dielectric breakdown properties of C4F7N-CO2 and C5F10O-CO2 mixed gases and perform a comparative analysis. To begin, we employed the Gibbs free energy minimization method to calculate the particle compositions of heated C4F7N-CO2 and C5F10O-CO2 gases. Subsequently, we used the two-term approximation Boltzmann equations to calculate key parameters such as the electron energy distribution function, reduced ionization coefficient, reduced attachment coefficient, and reduced critical breakdown field strength of post-arcs. Furthermore, we conducted an analysis to examine the influence of temperature, pressure, and CO2 content on the post-arc hot gas breakdown characteristics. Our study revealed that the inclusion of CO2 substantially decreases the concentration of high-energy electrons, and generally, higher pressure levels correspond to a reduction in the probability density of high-energy electrons. This work was supported by the State Grid Jiangsu Electric Power Co., Ltd. Technology Project (J2023026).