GISに直流電圧が残留した場合における絶縁スペーサの絶縁特性に関する検討の一環として，絶縁物表面層の抵抗率を決定する要因及び，電界放射によるスペーサ帯電現象各々を実験的計測に基づき検討した。得られた結果を以下に整理する。%Gas insulated switchgear (GIS) has widely been used for the AC power distribution because of its high reliability and compactness. Recently, DC GIS has been developed with various investigations for dielectric breakdown characteristics of DC gas-insulation. GIS insulation is composed of SF_6 gas and solid spacers, and it has been recognized that the dielectric performance of DC GIS is mainly influenced by solid spacers. Under the DC stress, the electric field is directed in one way, the effect of electrification for charges to be accumulated in the spacer must be taken into account and also the effect exists in AC GIS because the switching operations may leave the remanent DC charge on the AC GIS spacer. This paper first describes the effective resistivity (the bulk or the surface) of the solid spacer under the DC stress from the experimental investigation, and the critical factor on the solid spacer what cause to reduce the dielectric performance of the GIS insulation is studied. Secondly, the present paper deals with the electrification on the GIS with various surface roughnesses of epoxy insulator and metallic electrode. Finally, the DC insulation characteristics of GIS insulator are investigated from the experimental results.
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