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 r e l i a b i l i t y of 500 kV dc GIS. Considering problems of metallic particles and charge accumulation on spacers, the developed insulation structure of GIS c o n s i s t e d of three regions, i . e . the spacer, particle scavenging and n o n - l e v i t a t i n g r e g i o n s . Particles could be e f f i c i e n t l y scavenged, and the developed GIS withstood a l l insulation s p e c i f i c a - tions with sufficient margins under the clean and particle-contaminated condition. Now, a long-term s i t e test for one year of the 500 kV dc GIS has been continued since October in 1995.