The Quebec – New England Transmission (officially known in Quebec as the Réseau multiterminal à courant continu (RMCC) and also known as Phase I / Phase II and the Radisson - Nicolet - Des Cantons circuit, and known in New England as the Northern Pass) is a long-distance high-voltage direct current (HVDC) line between Radisson, Quebec and Westford Road in Ayer, Massachusetts. As of 2012, it remains one of only two Multi-terminal HVDC systems in the world (the other one being the Sardinia–Corsica–Italy system, completed in the same year) and is "the only multi-terminal bipole HVDC system in the world where three stations are interconnected and operate under a common master control system". History Initially, the Quebec – New England Transmission consisted of the section between the Des Cantons station near Windsor, Quebec and the Frank D. Comerford Dam near Monroe, New Hampshire which, because of the asynchronous operation of the American and Québec power grids, had to be implemented as HVDC. This bipolar electricity transmission line, which is overhead for its whole length except the crossing of Saint Lawrence river, went into service in 1986. It could transfer a maximum power of 690 megawatts. The operating voltage was ±450kV or 900 kV from line to line. The line was planned to extend beyond the two terminals at Des Cantons and Comerford to the hydroelectric power plants of the La Grande Complex, in the James Bay region of Québec, and to the high consumption area around Boston, Massachusetts — specifically, by to the north toward the converter station at Radisson Substation, and to the south to the converter station at Sandy Pond in Massachusetts. The transmission power was increased by extending the existing converter stations to 2,000 megawatts, with the value of the transmission voltage remaining unchanged at ±450 kV. For the connection of the Montreal area, a further converter station at Nicolet was put into service in 1992 with a transmission capacity of 2,000 megawatts. The line crosses the Saint Lawrence River between Grondines and Lotbinière via a tunnel. Until the tunnel was built, the line crossed the river via an overhead lattice tower electricity pylon—portions of one of these towers would later be used as part of the observation tower at La Cité de l'Énergie in Shawinigan. Failed Northern Pass initiative In December 2008, Hydro-Québec, along with American utilities Northeast Utilities (parent company of Public Service of New