site of the proposed Conawapa Generating Station at A 1,324 km bipolar transmission line operating at nominally +/-500 kV, running to the West of Lake Manitoba Riel Converter Station, on the east side of the Winnipeg Floodway, in the Rural Municipality of Springfield at Additional 230 kV AC lines for the northern collector system. The line uses guyed steel towers in northern stretches of the line and self-supporting steel lattice towers in the southern part. On average there will be about two structures per kilometer. Each tower carries a bundled conductor for each pole. Each pole conductor is made of three sub-conductors equivalent to 1,590 MCM ACSR. Conductors are supported by toughened glass or porcelain strain insulators with a maximum clearance to ground level of 34 meters, with a minimum of 13.2 meters at mid span and maximum conductor sag. The top of the towers carries an optical ground cable providing grounding interconnection for the towers and optical fibers for control and communication of the system. Typically the right-of-way for the HVDC line is 66 meters, with 45 meters cleared directly below the line. The system is capable of transmitting 2000 megawatts from the Nelson River stations to loads in the south. Ground return electrodes Although normally each of the lines run as bipolar systems, if a pole is shut down for maintenance or a fault, the ground return electrode is used to maintain partial capacity operation. Bipoles 1 and 2 share a ground electrode of ring type, in diameter, from the Dorsey Converter Plant at . The Dorsey electrode is connected with the converter plant by two overhead lines on wooden poles, one for Bipole 1 and one for Bipole 2. At Radisson, Bipole 1 uses a ground electrode of the same size and type as Dorsey, but only away from the station at . Bipole 2 uses a ground electrode in diameter, and from the Henday Converter Station . Bipole 3 has a ground electrode site near the Keewatinoow Converter Station at connected by a 30 km electrode line. At the southern Riel Converter Station, the electrode line runs about 26 km to a grounding electrode site at near Hazelridge, Manitoba. References External links Manitoba Hydro https://web.archive.org/web/20051115122606/http://www.transmission.bpa.gov/cigresc14/Compendium/NELSON1.htm https://web.archive.org/web/20051115122606/http://www.transmission.bpa.gov/cigresc14/Compendium/NELSON2.htm https://web.archive.org/web/20051115122606/http://www.transmission.bpa.gov/cigresc14/Compendium/Nelson2%20Pictures.pdf Siemens HVDC Reference List Nelson River HVDC System (with pictures of the valves) Energy in Manitoba HVDC transmission lines Electric power infrastructure in Canada Energy infrastructure completed in 1972