Due to the greenhouse effect, the use of sulfur hexafluoride (SF6) is subject to significant restrictions. SF6 has a global warming potential (GWP) 23,900 times that of CO2 and a lifetime in the atmosphere of 3,400 years. The atmospheric concentration of SF6 has been increasing at an annual rate of 8.7%, now accounting for over 15% of total greenhouse gas emissions. Electrical equipment is the primary source of SF6 emissions, accounting for approximately 70% of the total. The 1997 Kyoto Protocol mandates a substantial restriction of SF6 use by 2020. The toxicity of other decomposed products has also made the search for SF6 alternatives for use in gas-insulated equipment a pressing requirement for power grid development. Manufacturers and users are increasingly interested in alternatives to SF6.
Currently, three primary types of alternative gases are under research: conventional gases (air, N2, and CO2), SF6 mixtures, and highly electronegative gases and their mixtures. In addition to the physical and chemical properties of these three types of gases, experiments and theoretical studies have been conducted on their electrical properties. Although conventional gases offer stable properties and dielectric strength less than 40% of SF6, they can replace SF6 as an insulating medium in some medium- and low-voltage equipment. Sulfur hexafluoride (SF6) gas mixtures can generally meet the insulation requirements of these equipment and, with their lower liquefaction temperature, are suitable for use in cold and high-altitude regions. However, this cannot completely eliminate the use of SF6 and fundamentally address the greenhouse effect. Electronegative gases generally have higher liquefaction temperatures, necessitating the use of mixed buffer gases.
In recent years, in-depth research has been conducted on the insulation properties, discharge and overheating differentiation characteristics, product safety, and the mechanisms of action of key factors such as trace water and trace oxygen on new insulating gases, such as C4F7N, C5F10O, and C6F12O. Alternative gas solutions suitable for various application scenarios have been proposed, and research has been conducted on the synergy and compatibility of these new insulating gases with solid materials.
The use of existing alternative gases alone has limitations. Future applications of insulating gases may utilize multicomponent mixtures and combined gas and solid materials. While some progress and engineering applications have been achieved in the insulation properties of alternative gases, no significant breakthroughs have been made in arc extinguishing performance.
Post time: Aug-04-2025