Fundamental Investigation for Firefly Phenomenon of Particle under DC Voltage in SF₆ Gas

Abstract

GIS is compacted by progress of arrester and reduction of impulse test voltage for specifications recently. Since field strength of inner surface for GIS tank is more strengthened than ever, it is more necessary that included particle in GIS is taken into consideration. When GCB and DS are opened, residual dc voltage occurs at conductor between GCB and DS. It is well known that movement of particle under ac voltage is different from that of dc voltage. Therefore it is very important that particle movement under dc voltage is taken into consideration, even if GIS is for ac.
From the above, this paper deals with firefly phenomenon of particle under dc voltage in SF₆ gas. It investigates that prevention of fire fly phenomenon by electric field strength of conductor. And the minimum electric field strength to continue firefly phenomenon of particle is made clear. Then the breakdown voltage with firefly particle is compared with that of particle; with a minute gap, fixed to conductor.