Study of the Arc Interruption Performance of CO₂ Gas in High-Voltage Circuit Breaker

CO₂ is a possible alternative to SF₆ as the interruption medium in gas circuit breakers. The arc interruption performance of CO₂ is investigated in this paper, by combining the computational fluid dynamics (CFD) analysis and the Mayr arc model. The interruption processes for a high-voltage circuit breaker filled with CO₂ at 0.6, 0.8, and 1.0 MPa, as well as SF₆ at 0.6 MPa, are investigated, and the influence of the filling pressure on the gas flow field characteristics is analyzed. It is found that the SF₆ arc has a higher arc core temperature and a smaller arc radius than CO₂ arc. The arc core temperature and arc radius both decrease with the increasing the filling pressure. The mass fluxes along the axial and radial directions and toward both the nozzle side and the hollow contact side are presented and analyzed. The time constant and arc cooling coefficient at the current-zero point are calculated based on the Mayr equation. Finally, the critical values of the rising rate of the recovery voltage (RRRV) and relative di/dt are obtained. The interruption capabilities of CO₂ at 0.6, 0.8, and 1.0 MPa are estimated to be about 47%, 76%, and 95% compared with that of SF₆ at 0.6 MPa, respectively, with the assumption that the Mayr equation is applicable to analyze the interruption capability of different gases.