中文摘要：

CO2是高压断路器中常用SF6的一种极具潜力的替代气体。文中分别计算了CO2、CO2-O2、CO2-N2、CO2-CH4和CO2-H2等混合气体在不同混合比例、压力和温度（300~4 000 K）下的临界击穿强度（E/N）cr。通过Gibbs最小自由能方法,计算了气体组分,挑选混合气体中的主要粒子。以计算出的粒子组分为输入参数,通过二阶近似的Boltzmann方程,获得不同条件下CO2及其混合气体的临界击穿强度。计算结果表明,CO2-O2、CO2-CH4和CO2-H2会提升CO2的临界击穿强度。文中获得了高温条件下CO2及其混合气体的绝缘特性基础数据,为寻找SF6替代气体提供了理论依据。

英文摘要：

CO2 is a potential alternative for SF6 in the high voltage circuit breaker. In this paper, the critical re- duced electric field strength （E/N）Cr of CO2, CO2-O2, CO2-N2, CO2-CH4 and CO2-H2 at different mixing ratios, pressures and temperatures （300--4 000 K） have been calculated. The species composition of CO2 gas mixtures was calculated based on the Gibbs free energy minimizing to pick out the main species. Then the （E/N）Cr of CO2 gas mixtures at different conditions were derived by solving the two term approximation of Boltzmann equation. The re- suits indicate that the （E/N）= of CO2-O2, CO2-H2 and CO2-CH4 are higher than that of other mixture gases. The fun- damental data of the insulation properties of CO2 and its mixtures under high temperature are obtained,which pro- vides a theoretical basis for the search of substitute gases for SF6.