User Guide for Non-SF6 Gases and Gas Mixtures in Substations

Gas-Insulated Switchgear (GIS) has been widely deployed since the late 1960s due to its compact design, high reliability, resistance to environmental influences and enhanced personnel safety. Sulphur hexafluoride (SF₆) has played a key role as a dielectric and arc-quenching medium in medium- and high-voltage switchgear, offering excellent electrical, thermal and interruption performance. However, SF₆ is a potent greenhouse gas, and its environmental impact has led to increasing regulatory pressure worldwide, including the European Union’s F-gas Regulation (EU) 2024/573 and regulations introduced by the California Air Resources Board.

In response, extensive research and development over recent decades has resulted in viable alternatives to SF₆, notably fluorinated gas mixtures and…