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The LIFE SF6-FREE HV BREAKER project aims to replace SF6 gas with a CO2-O2 gas mixture in circuit breakers, thereby reducing the carbon footprint while maintaining reliability and performance without increasing equipment dimensions, achieving a best-in-class life cycle assessment. Different gases exhibit varying properties and behaviors, which is why a direct substitution of SF6 with another gas in the equipment is not feasible. A redesign of the circuit breaker is necessary to accommodate the CO2-O2 gas mixture.
By the project's completion in early 2026, the SF6-free live tank circuit breaker will be suitable for the 420 kV voltage level and temperatures as low as -50°C. This new solution will be integrated into GE Vernova's GRiDEA portfolio, supporting electrical grid operators in eliminating the need for SF6 gas in their air-insulated substations and contributing to their decarbonization objectives.
Set-up of a prototype 420 kV/50 kA circuit breaker, the future GL316c model, at our Grid Solutions facility in Villeurbanne, France. This setup aims to fulfill the European grid operators’ requirements for LTCB before any onsite installation within a high-voltage transmission network. To achieve this, we will conduct a technical validation of the solution in accordance with international standards (IEC) through implementation tests on the optimized 420 kV CO2-O2 LTCB. The goal is to confirm the technical feasibility of a compact 420 kV/50 kA circuit breaker designed to operate with the CO2-O2 gas mixture while maintaining dimensions comparable to those of the commonly used SF6 circuit breakers.
Furthermore, a life-cycle assessment will be conducted to certify that the new circuit breaker offers a significant reduction in carbon footprint compared to its SF6 predecessor.
Following the completion of our initial objectives, the LIFE SF₆-FREE HV BREAKER team will proceed with the development process to downscale the 420 kV CO2-O2 LTCB, GE Vernova's upcoming GL316c model, to the 170 kV/50 kA voltage level. Existing project observers will be invited to continue collaborating with us on these advancements.
GE Vernova offers a CO2-O2 gas mixture as an alternative to SF₆, specifically used as an electrical arc switching medium. This mixture consists of 87% carbon dioxide (CO2) and 13% dioxygen (O2). Identified by our R&D experts as the most suitable option for live tank circuit breakers, this gas mixture delivers the targeted decarbonization benefits of an SF₆ alternative without compromising the technical performance or footprint of the equipment. Consequently, the gas mixture reduces its contribution to global warming by 99.9% compared to SF₆, while maintaining the same dimensions as the SF₆-based circuit breakers.
For more information on GE Vernova's alternatives to SF₆, please visit: GRiDEA - Decarbonization Portfolio | GE Vernova
The most challenging aspect of developing the LIFE SF6-Free HV Breaker project is designing the interrupting chamber to meet all critical tests defined by the IEC 62271-1 Switchgear Standard (IEC: International Electrotechnical Commission). Key tests include:
Having successfully passed these tests, we are now able to integrate the interrupting chamber into the circuit breaker design and finalize the development of our future CO2-O2 live tank circuit breaker. Typically, a 420 kV live tank circuit breaker includes two interrupting chambers placed horizontally at the top, forming a “T” shape. We are just a few months away from achieving our final objective—the launch of the GL316c circuit breaker, which will contribute to the decarbonization of high voltage air-insulated substations for 420 kV electrical networks.
In 2025, Scottish SP Energy Network, Polish PSE, and French EDF decided to closely follow the development of the circuit breaker dedicated to their 420 kV networks. These transmission system operators (TSOs) not only witness our progress but also contribute to designing a circuit breaker that meets their grid codes. As part of the project, they will be the first to implement our new GL316c, slated for release in 2026.
In August 2024, after developing a live tank circuit breaker at 145 kV and 40 kA with a CO2-O2 gas mixture, we announced at the CIGRE conference in Paris that the priority was to develop a new live-tank circuit breaker at 420 kV and 50 kA using CO2-O2 as the switching medium. This is now the objective of our LIFE SF6-Free HV Breaker project.
In June, we welcomed Swedish Vattenfall, Europe’s largest producer and retailer of electricity and heat, to our LIFE project’s team of TSOs, which includes French RTE, Spanish REE, and Danish Energinet. These three TSOs have been supporting the development of our circuit breaker since the beginning.
The initial switching tests of GE’s upcoming 245 kV 50 kA 50 Hz SF6-free live tank circuit breaker, which has been in development for a year, show very promising results. The short line fault clearance, one of the most demanding switching performances, was achieved after just two tests, without any additional capacitors and with a tdl < 0.1 µs, as required by the IEC 62271-100 standard for AIS applications.
Like other SF6-free switchgear, the performance was validated with a circuit breaker maintaining the same footprint as commonly used SF₆ breakers. We are confident this will inspire adoption of SF6-free technology by transmission system operators. The team is currently working on optimizing the interrupting chamber while preserving breaking and dielectric performance. Since the project’s inception, we have reduced the climate impact of our live tank circuit breaker, avoiding the use of around 40 kg of SF₆, equivalent to approximately 934 tons of CO2.
GE has welcomed three major transmission system operators (TSOs) from key European countries to our LIFE SF₆-FREE HV BREAKER project. In partnership with GE, the TSOs gained a better understanding of project objectives, received a technical overview, and met the team of experts developing a new SF₆-free live tank circuit breaker.
According to Joel Ozil, LIFE SF₆-FREE HV BREAKER Project Leader, “This collaborative working group will support our industry’s objectives around SF₆-free solutions. In parallel, the aim is also to identify pilot projects to accelerate the implementation of LTCBs in the upper-rated voltage range.”
TSOs’ Role
Similar to SSEN Transmission’s involvement with the LifeGRID project (co-funded by the EU Commission’s LIFE Programme) in Scotland, the TSOs involved in the LIFE SF₆-FREE HV BREAKER project will play a crucial role in the development of our new SF6-free LTCB by:
With national and European authorities pushing for SF₆ alternatives in high voltage networks, our LIFE SF6-FREE HV BREAKER project allows TSOs to gain reliable experience and trust in SF6-free solutions before changes come into effect. All three TSOs have agreed to further contribute to and follow up on our project.
GE looks forward to meeting with the team again later in the year to review our progress and welcomes other TSOs to join the working group.
Validate the technical viability of the combination of a new gas mixture based on GE’s g³ gas technology and the improved 245 kV/50 kA High Voltage Live Tank Circuit Breaker (HVLTCB) design for temperature down to -30°C
Integrate 420 kV/50 kA and 550 kV/50 kA technical requirements in the new HVLTCB design in order to ensure a solution fitting the whole 50 Hertz (Hz) high voltage (HV) air-insulated substation (AIS) applications.
