Comparison of measurement and numerical calculation on spectral profile of ablation arc plasma around current zero in high-voltage gas circuit breakers

A product-scale interrupter with a rated voltage range of 245 kV to 362 kV and current condition of 20 kA root mean square has been examined to study the arc extinguishing process and the appearance of absorption spectrum by C-2 molecules immediately before the current zero. The latter has elucidated the presence of C-2 molecules outside the arc core, where the temperature is lower. The temporal behaviour of the C-2 absorption spectrum and the emission spectrum of the S+ ion have been measured, which have indicated that polytetrafluoroethylene ablation gas is replaced by SF6 because of gas flow from the thermal puffer chamber to the stagnation point. The computed spectra agree well with the experimentally obtained spectra and show similarities to measured profiles. They show evidence of absorption by C-2 molecules in the continuous spectrum and the reproduced band heads of the C-2 Swan spectrum.