SSEN Transmission is among the first companies in the world to install the EconiQTM 420 kV Live Tank Breaker LTA that is free of sulphur hexafluoride (SF6) - the world's most polluting greenhouse gas.

The groundbreaking switchgear technology by Hitachi Energy will be deployed at SSEN Transmission's Connagill Super Grid Transformer substation upgrade project in Sutherland, with installation scheduled for summer 2026.

SF6, a powerful greenhouse gas, has been a mainstay in electrical switchgear for decades. Its high insulating and interrupting properties make it ideal for preventing electrical faults in medium and high-voltage electrical installations. But it is also a greenhouse gas many times more powerful than CO2 and there are global efforts to phase out its use.

The new circuit breaker will play a crucial role in supporting the integration of renewable energy sources and supports SSEN Transmission's strategy to no longer install equipment containing SF6 wherever viable. This is part of the company's wider decarbonisation ambitions, having been the world's first transmission network to be accredited by the Science Based Target initiative for its carbon reduction targets which are consistent with net zero.

Rob McDonald, Managing Director of SSEN Transmission, said: "We are delighted to collaborate with Hitachi Energy and order some of the world's first SF6-free 420 kV air-insulated switchgear circuit breakers, which is testament to our position as a leader in the adoption of SF6 alternatives.  


"The use of the technology is a key enabler to ensure we meet our ambitious grid expansion plans for 2030 and beyond, as well as our science-based carbon reduction target.  

" The equipment will be used for a substation upgrade project in the north of Scotland which will reinforce the local network and allow for the connection of several onshore wind farms, contributing to UK net zero targets." 

At next week's CIGRE 2024 Paris Session, SSEN Transmission and Hitachi Energy will announce their collaboration to install the world's first eco-efficient 420 kV LTA.

Markus Heimbach, Managing Director of Business Unit High Voltage Products at Hitachi Energy, said: "Our collaboration with SSEN Transmission exemplifies the power of innovation and partnership in addressing the urgent need for sustainable high-voltage energy solutions. By pioneering the adoption of SF6-free technology, we are not only reducing our environmental footprint, but also setting a new standard for grid infrastructure that balances performance with sustainability.”

SSEN Transmission was the first transmission operator in the UK to have a 145 kV SF6-free air-insulated switchgear circuit breaker at Dunbeath and the first in the world to order a 420 kV SF6-free gas insulated switchgear (GIS) board for Kintore. The new installation will serve as a model for other transmission operators worldwide, demonstrating the feasibility and benefits of adopting SF6-free alternatives.

For decades, SF6 gas has been used extensively across the electrical industry as an insulating gas for switchgear in substations.

In August 2020, SSEN Transmission announced ambitious plans to reduce its own emissions in line with what is required to meet net zero emissions, becoming the world's first electricity networks company to receive external accreditation for a science-based target consistent with a 1.5°C global warming pathway.

As part of this commitment, SSEN Transmission is focused in installing ground-breaking, innovative net zero technology across its network, with a particular focus on SF6-free technologies.

SSEN Transmission actively contributes to various national and international industry groups such as CIGRE and the ENA to help support the use of SF6-free technology across the transmission network on a global level.