Characteristics of g3 – an alternative to SF6

The current transmission and distribution network relies on SF6 technology because of its remarkable arc quenching properties and dielectric insulation. However, SF6 is a greenhouse gas with an extremely significant impact on global warming. It is one of the six gasses listed in the 1997 Kyoto Protocol designed to lower greenhouse gas emissions worldwide. In addition, as a fluorinated gas, SF6 is subject to various other regulations that intend to reduce emissions. GE jointly developed g3 (green gas for grid) with 3M™ Company, a leader in environmentally sustainable solutions. g3 has 98% less impact on global warming than SF6. With performances comparable to SF6, it is a suitable technology for the development of today's new generation of clean high- and ultrahigh voltage equipment. Equipment using g3 maintains the same dimensions and overall footprint, which are key environmental and economical factors for utilities. In order to obtain the same dielectric margin, the pressure level in some cases has to be increased relative to SF6 values but the operating pressures are limited to values already known in GIS, DT (Dead Tank) and LT (Live Tank). This paper describes the g3 characteristics in detail, with a focus on its use as current interruption medium.