Electric performance of new non-SF6 gases and gas mixtures for gas-insulated systems

Insulation gases are applied in electrical equipment such as Gas Insulated Switchgear (GIS) and Lines (GIL), high- and medium-voltage circuit breakers and switches. Sulfur hexafluoride (SF6) is widely used for decades as insulation medium in electrical equipment. However, SF6 is also a strong greenhouse gas with a global warming potential (GWP) of 23,500 (i.e. one kg of SF6 released to the atmosphere contributes to global warming as 23.5t of CO2 would do). Its use and handling is thus strongly regulated in most countries, and revisions of the legislation in some countries are even aiming at phasing out the use of SF6 in electric power equipment completely in the coming years to decade. Several alternative insulation technologies exist, such as air insulation, solid insulation, liquid insulation, or gas insulation with natural-origin and/or new molecules.