Evaluation on current interruption ability of CO2 and SF6 using current and voltage application highly controlled by power semiconductors

This paper reports a new simple test technique to evaluate current interruption ability of arc quenching gases. In the test, current and voltage applied to the arc was controlled using a insulated gate bipolar transistor (IGBT). Switching the IGBT enables us to produce free recovery conditions for a fundamental arc decay in nozzles. In addition to this, a voltage was intentionally applied to the free recovery arcs between the electrodes by switching-off IGBT again at the specified delay time t_d. This applied voltage is called quasi transient recovery voltage (quasi-TRV). We can evaluate successful interruption or interruption failure by measuring the current between the electrodes after quasi-TRV application. We compared the interruption ability of SF₆ and CO₂ through this developed technique. The experimental results show that a residual arc in SF₆ gas flow decays four times more rapidly than that in CO₂ gas flow. Influence of observation holes in the nozzles used in the experiments was also investigated, showing less influence of observation on the arc behavior.