Experience with SF6 Gas-Insulated Substations and Proposals for Improved Reliability

Ontario Hydro has had four or more years of service experience with four gas-insulated substations (GIS) rated at 500 kV and 230 kV and 80 kA. Initially, the stations were fraught with problems, due mainly to the equipment being prototype. Most of the problems have now been corrected and the reliability and maintainability of the stations are satisfactory, comparable to the rest of the system. A number of proposals are made to improve the reliability of future GIS.