A COMPUTATIONAL FLUID-DYNAMICS SIMULATION OF HIGH-CURRENT AND LOW-CURRENT ARCS IN SELF-BLAST CIRCUIT-BREAKERS

Computational fluid dynamics calculations for high- and low-current ar cs in an interrupter of the self-blast type have been performed. The m ixing process of the hot PTFE cloud with the cold SF6 in the pressure chamber is strongly inhomogeneous. The existence of two different spec ies has been taken into account by interpolation of the material funct ions according to their mass fraction in each grid cell. Depending on the arcing time, fault current and interrupter geometry, blow temperat ures of up to 2000 K have been found. The simulation results for a dec aying are immediately before current zero yield a significantly reduce d are cooling at the stagnation point for high blow temperatures.