Influence of Ablation on Differential Arc Resistance


  • L. S. J. Bort High Voltage Laboratory, Eidgenössische Technische Hochschule, Zürich
  • V. Freiermuth High Voltage Laboratory, Eidgenössische Technische Hochschule, Zürich
  • C. M. Franck High Voltage Laboratory, Eidgenössische Technische Hochschule, Zürich



axially blown arc, ablation, passive oscillation, MRTS, HVDC CB


The influence of ablation on the du/di behavior of an arc in a model gas circuit breaker was examined. Specifically the transition from a state without ablation in the nozzle towards states with ablation was of interest, since prior work indicated that for high currents the voltage becomes constant or du/di gets even positive if ablation is present. Measurements with different blow pressures and rectangular DC currents of varying amplitude were compared, using PMMA-nozzles and dry air as blowing gas. Ablation was measured by weighing the nozzle, scanning the cross section, and using a coordinate measuring machine. The results agreed well, and confirmed that higher pressure shifts the du/di curve towards more favorable values.


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