Circuit breaker, a part of system called switchgear in the electric power grid, is used widely for switching high power under live power flow conditions. A safety device, the circuit breaker works akin to the common household electrical switches. The difference lies in the magnitude of power handled by the device, which is some one billion times that of light switches at our homes.

Handling around 420 kilovolt (kV) and 63,000 amperes (A) of power at the time of switching, the core arcing temperatures can reach up to 20,000°C while the overall contact separation speed reaches 120 km/h within a span of tens of milliseconds. To quench this arc and provide electrical insulation at the same time, a gas called sulphur hexafluoride (SF₆) is widely used in high voltage switchgear due to its unique thermal, insulating and arc quenching properties during switching of high voltage, high current lines.

While SF₆ fulfils critical requirements of electric grid, it is a greenhouse gas 24,300 times more potent than CO₂, that stays in the atmosphere for over 1,000 years. As it brings a significant environmental threat and liability, research efforts had been underway for several decades to replace SF₆.

Breakthrough in Circuit Breaker Technology

To help the power sector tackle this problem, Hitachi Energy has come out with the world's highest volt-age SF₆-free switchgear — the EconiQ™ 550 kV circuit breaker that can be used in gas-insulated switchgear (GIS) or as a standalone 420 kV circuit breaker. Developed with the help of scientific and engineering principles, as well as design rules, the EconiQ™ portfolio delivers on all parameters. The C₄-FN gas used in small percentages within the eco-efficient EconiQ™ mixture enables the equipment to retain its compact size and minimize material usage, which further reduces the overall carbon footprint. By maintaining the reliability, performance, scalability and compactness of conventional SF₆-based products, EconiQ™ ensures a seamless transition for customers.

For instance, each new 550 kV GIS substation using EconiQ™ eliminates the carbon equivalent of 170 fully booked jumbo jets flying from Paris to New York while retaining the size, performance, and relia-bility levels of traditional switchgear. There are, and there will be thousands of such high voltage switch-gears (circuit breakers and substations) that can use this SF₆-free technology for a significant change in reducing carbon footprint in the electric grid.

How Does EconiQ™ Fare

Replacing SF₆ in high-voltage to reduce the impact of greenhouse gas emissions in the global power industry is important for moving towards carbon-neutrality. A diluted mixture of natural gases with 3.5 per cent of F-gas with a Global Warming Potential (GWP) of 390 is used, essentially eliminating the car-bon footprint of SF₆ (GWP of ~25,000). Diluted mixture is non-toxic, does not accumulate in water, plants, or soil, and decomposes in the atmosphere into natural substances.

It delivers same technical performance, size and reliability as
SF₆ equipment

Developed and available today

Lowest carbon footprint in life cycle assessment (low material-use)

EconiQ™ is eco-efficient system for sustainability, where products, services and solutions are proven to deliver exceptional environmental performance. This SF₆-free innovation will go a long way in not only making the energy assets environment-friendly but also helping the energy transition towards net-zero.#

Akilur Rehman is Chief Technology Officer and Market Innovation Lead-South Asia at Hitachi Energy.