WP1 – Grid of the Future
MISSION developed scenarios for Europe’s transition to SF₆-free technologies, quantifying emissions, equipment needs, and reliability. Accelerated adoption can cut emissions by up to 20% versus business-as-usual without compromising resilience. A vulnerability study found no new systemic risks but stressed the need for standardization and operational experience. Metrics for environmental and cost evaluation (LCA, LCC) were proposed to guide future decisions.
WP2 – SF₆ Alternatives for AC and DC Switchgear
The project advanced understanding of alternative gas mixtures through open-access swarm data and discharge models for N2/O2/CO2. A 1D breakdown model and 3D PD simulation framework were developed and validated experimentally. High-voltage test setups for breakdown and PD detection are operational, enabling systematic validation and supporting design of SF₆-free insulation systems.
WP3 – Technical Requirements and Pilot Planning
Type-test requirements for 420 kV SF₆-free circuit breakers were defined per IEC 62271-100, with additional tests for overhead lines and extreme climates. Two pilot sites were selected: Dagali (Norway) for severe cold (–50 °C) and Marsillon (France) for high temperatures (+40 °C). Monitoring plans include fault recorders, transient voltage tracking, gas density monitoring, and optional X-ray emission checks.
WP4 – 420 kV SF₆-Free Live-Tank Vacuum Circuit Breaker
The conceptual design of the 420 kV vacuum CB was completed with dielectric and thermal simulations confirming compliance. A prototype was built and tested, validating vacuum interruption and clean-air insulation at this voltage level. Mechanical endurance and switching performance were assessed, and preparations for full type testing are underway, marking a major step toward the first SF₆-free 420 kV AIS breaker at TRL 8.
WP5 – 550 kV HVDC GIS with N2/O2
A 550 kV DC GIS design using N2/O2 insulation was derived from AC GIS platforms and validated through dielectric withstand, temperature rise, and insulation system tests. New components such as RC dividers, zero-flux CTs, DC bushings, and surge arresters were developed. Manufacturing tools for critical parts have been ordered, and type testing is scheduled for 2026, positioning the project to deliver the first SF₆-free HVDC GIS at TRL 8.
WP6 – New Generation of Fast Mechanical MVDC Circuit Breakers (12 kV)
A PSCAD model for a 12 kV LC-type DC breaker was developed and validated, demonstrating interruption of up to 6.5 kA within 0.5–2 ms. A prototype ultrafast disconnector achieved >16 m/s opening speed and a 10 mm stroke in 1.6 ms, confirming rapid commutation feasibility. Experimental work on arc dynamics and dielectric recovery advanced understanding of post-arc behaviour. Next steps include TRL 6 system-level demonstration and industrial design for manufacturability, with scalability to 40–80 kV.
