State Grid Corporation of China commissions 1,000 kV Su Tong gas-insulated line

The State Grid Corporation of China has commissioned the 1,000 kV Su Tong gas-insulated transmission line (GIL) utility tunnel project. The GIL utility tunnel spans 5.8 km and is the world’s first tunnel enabling underground UHV transmission. The project, running under the Yangtze river, links two cities, Suzhou and Nangtong in Jiangsu province, and has been constructed by the State Grid’s subsidiary in Jiangsu province. The project entailed the construction and installation of a 35 km long single-phase GIL  75 metres under the river.