Investigation of the effects of pressure ratios on arc behavior in a supersonic nozzle

Supersonic nozzles are commonly used in modern high voltage circuit breakers. The thermodynamic and electrical behavior of arcs burning in such nozzles is closely related to the nozzle geometry and the pressures at the nozzle inlet and exit. Computational investigation has been carried out on the thermal interruption capability of a supersonic nozzle at different inlet stagnation pressures and at different exit pressure to inlet stagnation pressure ratios (referred to as pressure ratios). The critical rate of rise of recovery voltage (RRRV), which is the most important parameter determining the thermal interruption capability of a circuit breaker, was predicted for five pressure ratios at three inlet stagnation pressures. The predicted RRRV values are compared with the test results of Campbell et al. (1976).