Development of Insulation Structure and Enhancement of Insulation Reliability of 500 KV dc GIS

The paper describes the development of insulation structure and enhancement of insulation reliability of 500 kV DC GIS (gas insulated switchgear). Considering problems of metallic particles and charge accumulation on spacers, the developed insulation structure of GIS consisted of three regions, i.e. the spacer, particle scavenging and nonlevitating regions. Particles could be efficiently scavenged, and the developed GIS withstood all insulation specifications with sufficient margins under the clean and particle-contaminated condition. Now, a long-term site test for one year of the 500 kV DC GIS has been continued since October in 1995.