An investigation of breakdown voltage with small arc current due to poor contact in SF/sub 6/ gas

Breakdown mechanism of a gap with a small arc current in SF/sub 6/ gas

“…As shown in (1) decomposition products such as SF4, SF2 and S2F2 are produced. If water vapor has not been thoroughly removed, the gases such as HF, Has, SOF2, SO2 and SOzFz are also produced by reactions of the decomposition products and water vapor as shown in (2). These formulas are typical ones of many reactions .…”

“…Gas heated by the arc is diffused by convection and thermal conduction [2-71, and reduces the breakdown voltage because of its lower density [2].…”

“…Also, the gap between the electrodes corresponds to the disconnected gap of the poor contact. This paper deals with the experimental results of the breakdown voltage between the electrodes and the disc when an arc is kept ignited in the gap between the electrodes, using the same experimental apparatus as the previous report [2]. The purpose is to investigate the influence of the distance between the electrodes and the disc, the pressure of SFe gas in the apparatus, the gap length between the electrodes, and the electrodes material.…”

“…Under the poor contact conditions, a discharge may occur in a disconnected gap formed by melting due to heating of the high resistance part, and may trigger a breakdown between the contact portion and the grounded wall of GIs. Therefore, we have reported the influence of the hot gas heated by such discharge arcs on the breakdown experimentally and theoretically [2]. In [2], the experimental apparatus consists of a pair of cylindrical rod electrodes arranged in a rod-to-rod gap with a disc set above or below the electrodes.…”

“…Therefore, we have reported the influence of the hot gas heated by such discharge arcs on the breakdown experimentally and theoretically [2]. In [2], the experimental apparatus consists of a pair of cylindrical rod electrodes arranged in a rod-to-rod gap with a disc set above or below the electrodes. The electrodes represent the poor contact, and the disc represents the grounded GIS wall.…”