SF6-free 245kV breaker moves toward pilot

Siemens Energy is advancing an F-gas-free 245kV live tank vacuum circuit breaker through the LIFE BLUE 245kV project, adding a high-voltage pathway for networks moving away from sulphur hexafluoride.

The project is developing a one-break live tank vacuum circuit breaker that uses a clean air insulation mixture of 80% nitrogen and 20% oxygen. The gas mixture has zero global warming potential and is paired with vacuum switching technology for transmission-level applications. Development covers design, engineering, modelling, type testing, pilot implementation, field operation, impact assessment, and scaling.

Under the EU’s revised F-gas Regulation, the use of gases with a global warming potential above one in new electrical switchgear installations above 52kV will tighten from 2028. SF6 has long been used in high-voltage switchgear because of its dielectric and arc-quenching performance, but its environmental profile has made new equipment selection more complicated for utilities planning long asset lives.

The LIFE BLUE 245kV breaker is designed to meet grid requirements under IEC 62271-1 and IEC 62271-100, covering insulation, switching performance, thermal behaviour, mechanical stability, and environmental resistance. Standardised components are also being used to reduce production complexity, shorten delivery times, and simplify future qualification of materials and suppliers.

A pilot installation with Red Eléctrica in Spain is planned for 2029. The pilot will replace an existing SF6-insulated live tank circuit breaker with an N₂/O₂ solution after type tests and qualification procedures are completed. Field operation will assess on-site handling, gas quality, system tightness, switching behaviour, and long-term stability under real network conditions.

Transmission operators are not evaluating SF6 alternatives on emissions alone. Replacement equipment must satisfy requirements on footprint, switching performance, reliability, maintenance, compatibility with existing substations, and lifetime cost. Clean air insulation avoids the gas handling, recycling, reporting, and leakage-management requirements associated with SF6 and other F-gases, while vacuum interrupters provide high dielectric strength, fast current interruption, and low contact wear.

The same switchgear transition is already visible at lower voltage levels. Schneider Electric’s UK launch of MCSeT switchgear combined SF6-free vacuum breaker technology with connected monitoring, digital operation, and predictive maintenance for medium-voltage distribution applications. Sustainability, asset visibility, and operational safety are being bundled into the same equipment modernisation cycle.

At 245kV, the engineering hurdle is higher. Transmission assets have long operating lives, strict availability requirements, and higher consequences from failure. Substation equipment can remain in service for decades, so choices made during the current replacement and reinforcement cycle will influence gas inventories, maintenance requirements, and environmental exposure far beyond the current regulatory timetable.

Large-scale grid expansion is also increasing demand for high-voltage equipment. Offshore wind connections, interconnectors, grid reinforcement, industrial electrification, and data-centre load growth are all driving substation work. Against that investment cycle, SF6-free alternatives must move from demonstration into repeatable procurement, installation, operation, and maintenance practice.

A successful pilot would give transmission operators another field reference for procurement decisions where SF6 reduction is now tied to compliance, lifecycle management, and equipment availability. The next phase will depend on whether the technology can combine environmental performance with the operating confidence that high-voltage networks require.