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Study of an ablation-dominated arc in a model circuit breaker

A switching arc in a model circuit breaker is studied by means of CFD simulations and optical emission spectroscopy. The arc is initiated between tungsten–copper electrodes in a carbon dioxide atmosphere and is led through PTFE (polytetrafluorethylene) nozzles. Radiation emitted by the arc plasma is absorbed by the surface of the nozzles leading to ablation of the wall material. The CFD simulations are based on a model of the arcing zone including a consistent treatment of the radiation transport and wall ablation. Carbon ion line radiation is analysed in the experiment using an optical path in the heating channel between the nozzles. Temperature profiles obtained from spectroscopy and simulations are compared. The pressure value in the arc is estimated based on the line width-intensity dependence. The obtained values correspond to the measured pressure outside the arc. Coincidence in temperature for the peak current and discrepancy on the falling edge are found and discussed.