IN Brief:
- The Horizon Europe-backed MISSION project is developing SF6-free switchgear components for AC and DC power systems.
- The project includes a 420kV AC vacuum circuit breaker, 550kV HVDC gas-insulated switchgear, and 12kV MVDC circuit breaker.
- The work supports the shift away from sulphur hexafluoride as F-gas restrictions tighten across European grid equipment.
The MISSION project is developing SF6-free switchgear for future AC and DC electricity networks, targeting one of the most technically difficult emissions challenges in transmission and distribution equipment.
The Horizon Europe-backed programme is developing and demonstrating three key components: a 420kV AC air-insulated live-tank vacuum circuit breaker, a 550kV HVDC gas-insulated switchgear system using pressurised technical air, and a 12kV MVDC air-insulated circuit breaker.
Sulphur hexafluoride has been widely used in high-voltage switchgear for decades because of its insulation and arc-quenching performance. It allows compact equipment designs and reliable switching under demanding electrical conditions. Its environmental profile has become a major concern because SF6 is a highly potent greenhouse gas, with leakage risks across filling, operation, maintenance, and end-of-life handling.
Replacing SF6 is technically demanding, particularly at higher voltages and in compact equipment. Medium-voltage alternatives are now more established, but higher-voltage AC equipment and DC switchgear require more advanced solutions. Electrical stresses, insulation distances, fault interruption duties, and space constraints all become more difficult as voltage rises.
MISSION is addressing both current AC network requirements and emerging DC architectures. That combination is significant because future grid expansion is expected to involve more HVDC transmission, offshore grid links, interconnectors, superconducting systems, and power-electronics-heavy infrastructure. DC networks need protection and switching equipment designed around different fault behaviour and operating characteristics from conventional AC systems.
The project’s use of vacuum interruption, pressurised technical air, and gas mixtures based on nitrogen and oxygen reflects the wider search for alternatives that can meet utility requirements without relying on high global warming potential gases. Equipment must still satisfy the performance, reliability, maintenance, and lifecycle expectations of transmission and distribution operators.
European F-gas regulation is increasing pressure on manufacturers and asset owners to move away from SF6 in new switchgear. Restrictions are tightening across voltage classes, and equipment specified today may remain in service for decades. Procurement choices made during the current grid expansion cycle will therefore shape emissions, maintenance regimes, and compliance exposure well into the future.
Grid expansion will increase the volume of switchgear needed across Europe. Renewable generation, storage, interconnectors, electrified industry, and transport infrastructure all require substations, protection equipment, circuit breakers, and control systems. Building that network with lower-emission equipment will require credible alternatives across medium-voltage, high-voltage, AC, and DC applications.
Demonstration remains the decisive stage. Laboratory performance has to translate into equipment that can operate in substations, converter stations, offshore environments, and constrained sites. Utilities need evidence of switching reliability, dielectric performance, asset life, maintenance requirements, and compatibility with existing network practices.
MISSION sits at the point where grid decarbonisation moves beyond generation assets and into the equipment used to operate the network itself. Low-carbon power systems still depend on physical infrastructure, and switchgear remains one of the critical components determining whether networks can expand safely, reliably, and with lower lifecycle emissions.