Underground links by gas insulated transmission lines

The concern to reduce the number of increasingly contested power transmission lines has led utilities and manufacturers as ALSTOM to search for new underground solutions. Today, the penetration of power lines into the heart of large cities is seriously hindered by the density of population and urban expansion. Solutions must also be found that allow power to be continuously transmitted whilst respecting the environment and comfort of inhabitants. Considerable efforts have therefore been made in the development of new technologies in the field of gas insulated transmission lines, as an alternative to overhead lines in specific cases. The preferential field of application of gas insulated lines (GIL) is that of power transmission for voltages in excess of 245 kV. The GIL technology has many advantages compared to overhead lines (OHL) such as their insensitivity to pollution and adverse weather conditions, the reduced transmission joules losses (2 to 3 times less than with OHL) and the effective electromagnetic shielding. To guarantee a high level of reliability for the GIL, while making it cost-attractive, some innovative developments have been brought by ALSTOM to the basic gas insulated bus ducts technology.