electrical transmission line from Inga () at the mouth of the Congo River, specifically from the Inga Dam, one of Africa's three largest hydroelectric complexes, to the distant copper mining region then known as Shaba, today Katanga. It featured switching stations at Selo (near Kinshasa) (), Kikwit (), Kananga () and Kamina (), prior to delivering power to the Kolwezi Inverter Station(). Electrodes The electrode for the Inga static inverter plant is situated 39 kilometres away from the station at and designed as linear ground electrode with a resistance of 0.24 ohm, while the electrode of Kolwezi static inverter plant, which is situated 11 kilometres away from the station at is designed as three-legged ground star electrode with a resistance of 0.14 ohm. Technology This scheme, equipped from the outset with thyristor valves provided by Swedish subcontractor ASEA, was designed to transmit 560 megawatts, in the first phase, at a symmetrical bipolar voltage of ±500 kilovolts. Although not the first 500 kV HVDC project in operation (the ±533 kV Cahora Bassa scheme having been completed in 1977) it was the first such scheme to use only a single twelve-pulse bridge per pole. Consequently, its thyristor valves were the highest-rated in the world (in terms of voltage) at the time and remained so until the completion, in 2007, of the ±450 kV, single-converter NorNed scheme. The thyristor valves for Inga Shaba had 258 thyristors in series in each valve and were air-insulated and air-cooled. Inga Shaba was the longest HVDC transmission line in service until 2010, when it was overtaken by the 2071 km, ±800 kV, 6400 MW HVDC link from Xiangjiaba Dam to Shanghai in China. Because the line runs through relatively inaccessible terrain, an unusually broad right-of-way was cleared, at considerable expense, to ensure tower integrity. The line operated initially at only 10% of capacity. In the 1990s, prior to major social unrest, the line increased its power transmission to 200 MW, still considerably below design capacity. As of 2000, reliability had been poor with many thyristor failures at the inverter station. As of 2010, the line was still functional as far as Bandundu, the capital of Bandundu province, approximately northeast of Kinshasa. In 2009 ABB was awarded a contract to refurbish and modernise the converter equipment. This upgrade is due to be completed in 2013. See also Grand Inga Dam High-voltage direct current References Bibliography Kwitny, Jonathan Endless