Technical aspects of gas insulated transmission lines and application of new insulating gases

This publication gives information about the design, testing and long term experience of AC gas-insulated transmission lines (AC GIL). AC GIL does not include any switching devices such as disconnectors, earthing switches or circuit breakers so that the main electric focus is on the insulation capabilities only. A new installation process for reducing GIL costs with a new welding technique and a mobile factory will be reported shortly. Currently pure SF6 and N2 / SF6 gas mixtures are used for GIL, but research is being done concerning the application of alternative gases for insulation purpose to reduce the global warming potential (GWP). Based on the long term experience with AC GIL the analyzed gas mixtures are discussed and evaluated.