The 220,000-Volt System of the Hydro-Electric Power Commission of Ontario

Power requirements of the Commission´s 25-cycle Niagara System are outlined. Preliminary studies in connection with the choice of transmission voltage, location of terminal transformer station, etc. are discussed, together with the technical studies involved in the design of a system for transmitting 260,000 hp., 230 mi. at 220,000 volts, and transforming same at the receiving end, for interconnection with the existing 110,000-volt system. The Toronto-Leaside 220,000-volt transformer station is described, including the 220,000-volt switching arrangement, 45,000-ky-a. three-winding transformer banks, 110,000-and 13,200-volt switching arrangements, 25,000-kv-a. vertical-shaft out-door synchronous condensers, relaying, communication, and control. The 220,000-volt transmission system is also described, including the use of aerophotography in surveying the route and locating the towers, design of supporting structures, details of conductor supports, insulation, ground wire practise, etc. The paper concludes with a résumé of operating experience on the 220,000-volt system to date, and an outline of the future development of the system as at present anticipated.