Gas-Insulated Switchgear and Interrupter

The historical progress of gas-insulated equipment in Japan is reviewed and the trend of technologies is discussed in the present paper. Since gas-insulated switchgear (GIS) and gas circuit breaker (GCB) have been widely applied to substation equipment, advanced technologies for high realiability and compactness of GIS are still required. Recent progress of analytical technologies, using digital computers, can meet their requirements. Technologies of gas insulation have contributed to the application of the equipment for the power transmission system and been attempted to advance GIS, such as ultra high voltage (UHV) GIS and HVDC GIS, with electronic diagnostic technologies.