The 420 kV Milestone Enabling
SF₆-free GIS
LIFE21-CCM-FR-LIFE-SF₆ FREE-GIS/101074338
This project is co-funded by the EU LIFE
Programme
Completed in December 2022, the LifeGRID project aimed to develop a 420 kV / 63 kA SF₆-free high-voltage GIS circuit breaker using GE Vernova’s g³ gas. The circuit breaker is a critical component for a fully SF₆-free 420 kV gas-insulated substation. Co-funded by the EU LIFE Programme, the project successfully demonstrated feasibility at the highest voltage level used in European electrical grids. This achievement paves the way for the broad adoption of SF₆-free GIS technology across Europe and the development of other SF₆-free switchgear at all standard voltage levels.
LifeGRID’s Key Outputs
- Proven 420 kV feasibility: Design and validation of a 420 kV/63 kA SF₆-free GIS circuit breaker using a compact double-break architecture (two 245 kV interrupters integrated in one tank), meeting GIS pergormance and compactness needs.
- Tested to the most severe IEC duties: The circuit breaker passed the most stringent IEC test sequences, and 420 kV performance was demonstrated, marking the formal conclusion of the project in December 2022.
- Data and method at scale: A new g³ gas behavior database under arc (plasma) conditions, integrated into a multi-physics CFD model was created to optimize the interrupting chamber; 1,400+ simulations across 70+ designs help speed-up the design of the circuit breaker. 12 prototypes and IEC standard demonstrations resulted in the public unveiling of the first 420 kV g³ GIS circuit breaker in 2022 during the CIGRE conference in Paris.
- From lab to grid: SSEN Transmission, a major transmission sytem operator in Scotland, is currently installing nine T155g 420 kV g³ GIS bays and roughly two km of g³ GIL at their Kintore substation. This installation will help avoid the addition of about 350,000 tons of CO₂e on the Scottish grid. Energization is foreseen in 2026.
An Impressive Start
Launched in 2023, GE Vernova’s T155g 420 kV GIS translates LifeGRID’s outcomes into a real impact on the grids. With more than 200 bays ordered by European transmission system operators, the solution is already accelerating decarbonization by reducing reliance on SF₆ in new builds and replacements, cutting insulating-gas CO₂e over the equipment lifetime while preserving raw material use and a compact footprint that speeds deployment in space-constrained sites.
LifeGRID's Milestones
