Puffer characteristic calculation of a circuit breaker using fluorocarbon gas mixtures

Because of its high dielectric strength, good partial discharge capability, low global warming potential (GWP), none ozone depletion potential (ODP) and nontoxicity, fluorocarbon gas is possible substitute for SF₆, and can be used hopefully in electrical equipment, such as circuit breaker. In this paper, we calculate the pressure characteristic of circuit breaker using gas mixture containing fluorocarbon gas as arc quenching gas based-on the first law of thermodynamics and the law of hydrokinetics. The pressure characteristic curves of the gas chamber and the gas mass flow pass the nozzle are obtained through computation. In addition, the influences of mixtures ratio and nozzle throat diameter to the pressure and gas mass flow rate are achieved. It shows that the bigger ratio of fluorocarbon is corresponding to the bigger chamber pressure and relative bigger mass flow as to the same structural factor with no energy input; while considering the arc energy bigger ratio corresponding to smaller chamber pressure. And the nozzle throat diameter has a large impact on the pressure and gas mass flow rate. Besides, we also compared the gas pressure and gas mass flow rate of mixture gas with that of SF₆ gas. These results provide a helpful reference for the design of the new type circuit breaker.