Gas insulated transmission lines for high power transmission over long distances

The gas-insulated transmission line (GIL) has been optimised for the needs of the 21st Century, where high-power transmission lines are needed and overhead lines are often not suitable. It will be used as a power feeder into huge metropolitan areas because energy resources are usually far away from the load centre. Also, underground power transmission over long distances is economical with GIL if overhead line installations face technical or acceptance difficulties. The technology is based on over 30 years of experience with gas-insulated systems. The GIL exhibits the following differences in comparison with conventional cables: high power ratings (transmission capacity of 3000 MVA and more per system); and suitability for long distances (100 km and more without compensation of reactive power). The aim of the latest Siemens GIL development was to considerably reduce costs and to optimise the laying technique for long lines.