The HVDC Gotland, on the Swedish east coast, was the first fully commercial static plant for high voltage direct current transmission in the world. The first HVDC Gotland link (Gotland 1) went into service in 1954. It could transfer 20 megawatts over a 98-kilometer-long submarine cable between Västervik on the mainland and Ygne on the island of Gotland, with a voltage of 100kV. As a static inverter, Mercury arc valves were used. In 1970 the service was re-engineered to transmission capacity of 30 megawatts at a voltage of 150kV by using the first thyristor module for HVDC applications. However even this capacity was not high enough and in 1983 a new link, HVDC Gotland 2 (transmission capacity: 130MW, transmission voltage: 150kV, cable length 92.9 kilometers, 6.6 kilometre overhead line) and in 1987 HVDC Gotland 3 (transmission capacity: 130MW, transmission voltage: 150kV, cable length of 98 kilometers) were built. The latter made the HVDC Gotland 1 redundant and led to its deactivation and disassembly.
