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GE unveils world’s 1st 420 kV SF6-free g3 circuit-breaker for gas-insulated substations
GE unveils world’s 1st 420 kV SF6-free g3 circuit-breaker for gas-insulated substations

Paris, FRANCE – MARCH 29, 2022 – In a historical milestone for the power industry, GE Renewable Energy’s Grid Solutions (NYSE-GE) unveiled the world’s first 420 kV, 63 kA g³ gas-insulated substation (GIS) circuit-breaker1 prototype. The g³ circuit-breaker was presented to a group of leading transmission utilities from across Europe, at a recent virtual roundtable event. The performance achieved by the prototype means that the industry will soon have a viable SF6-free alternative for high voltage products. GE’s 420 kV fully g3 gas-insulated substation (GIS), which includes the g3 circuit-breaker, is expected to be commercially available in 2023.

A circuit-breaker is protective equipment that is critical to any substation and mainly used to cut or redirect power through another path if there is a problem on the electrical grid. This new circuit-breaker relies on GE’s game-changing g3 (pronounced “g”-cubed) gas-insulating and switching technology. g3 technology allows GE to build electrical equipment with the same high performance and compact size as traditional SF6 products², along with a gas CO₂e impact reduced by 99%.

“The development of GE’s 420 kV g3 circuit-breaker is a historical milestone for the power industry as it will allow utilities to accelerate the decarbonization of their electrical grids. Until today, there was no viable alternative to SF6 for GIS at the 420 kV level, the highest voltage level in Europe. This means that the g3 technology can also be applied to all existing main voltage levels around the world. We are proud to be at the forefront of the effort to create a cleaner grid and are currently developing other g3 circuit-breaker types, according to our roadmap,” said Vera Silva, Chief Technology Officer at GE’s Grid Solutions.  

To develop the 420 kV g³ circuit-breaker, GE’s LifeGRID project received funding from the European Union under the European Commission's LIFE Programme. GE’s Grid Solutions’ research and development experts collaborated with several European partners on the project, including SSEN Transmission, who contracted with GE in December 2020 to install the world’s first 420 kV g3 GIS featuring the g3 circuit-breaker, at its Kintore substation in Scotland.

“Delivering a network for net zero is core to our long-term strategy—although our environmental commitment extends much beyond that,” said Matthew Barnett, SSEN transmission electrical plant subject matter expert. “To help us achieve this, we’re delighted to support GE with the LifeGRID project, which works to overcome one of the biggest technical challenges in removing SF6 from new equipment through the development of a 420 kV SF6-free circuit-breaker. The successful testing performed so far is an important step in showing that the SF6-free circuit-breaker is technically achievable.”

Today, more than 30 leading electrical utilities from 12 European countries and South Korea have already adopted GE’s g3 products for their high voltage networks, avoiding the addition of more than a million tons of CO₂ equivalent to the grid. That’s the equivalent of removing about half a million petrol cars from the road for one year.

More on the LifeGrid Project

GE’s LifeGRID  project involves development of the 420 kV g³ circuit-breaker that will be the core component of the first-ever 420 kV g³ gas-insulated substation (GIS).

“GE’s LifeGRID project, co-funded by EU’s LIFE Programme, has been a great opportunity for us to collaborate with different partners in Europe to enhance our knowledge about our g3 gas technology while helping decarbonize electrical grids,” said Yannick Kieffel, GE’s Grid Solutions’ project leader for this EU-funded g³ project and CTO of High Voltage Switchgear-Power Quality Products (HVS-PQP) division. Partners include the Czech Republic’s Brno University and Germany’s Leibniz Institute for Plasma Science and Technology, who built the scientific database; CEA, a leading French technological research center taking part in specific materials and technologies development; and SSEN Transmission in the UK as the Transmission System Operators (TSOs) providing user feedback throughout the phases of product development and resulting final implementation.

For more information on GE’s high-voltage g³ substation equipment and product roadmap, visit the Grid Solutions website.

  • 1. Circuit-breaker: High-voltage 420 kV circuit-breakers are found at electrical substations on long-distance transmission networks. Circuit-breakers can be air-insulated or, when space is a constraint, gas-insulated.
  • 2. SF6: Due to its strong insulating and arc-quenching properties, SF₆ has been, and continues to be widely used in primary substation equipment in the transmission industry. It is, however, a greenhouse gas that contributes significantly to global warming, if leaked.
  • GE’s alternative to SF6 is g3 insulating and switching gas, representing the culmination of a decade of research and development by its teams in France, Germany and Switzerland in collaboration with 3M Company. The g3 gas mixture is based on carbon dioxide, oxygen, and 3M™ Novec™ 4710 Dielectric Fluid from the 3M fluoronitrile family. Fluoronitrile was identified by R&D experts as the most suitable additive to CO2 and O2 to reach the targeted environmental benefit of an alternative to SF6, without compromising the equipment’s technical performance and footprint. As a result, the global warming potential (GWP) of GE’s g3 gas mass in the equipment is 99% lower as compared to SF6
    GE’s g3 gas-insulated products are currently available for live-tank circuit-breakers and gas-insulated substations (GIS) up to 145 kV, as well as gas-insulated lines (GIL) up to 420 kV.
    More about g3 – GE’s alternative to SF6 (
    More about g3 development, GE’s fluoronitrile based gas mixture: In search of an SF6 replacement | Think Grid (