News Release

- Accelerating development toward commercialization in fiscal year 2028 -

Kawasaki, Japan – Toshiba Corporation has confirmed the fundamental performance of a 300 kV gas‑insulated switchgear (GIS) and a gas circuit breaker (GCB) that completely eliminate use of sulfur hexafluoride (SF₆), a highly potent greenhouse gas, and replace it with natural-origin gases. Verification tests at Toshiba’s Corporate Laboratory have confirmed basic performance, including safe and reliable interruption and insulation of electric current. This achievement is an important step toward practical application of high‑voltage transmission and distribution equipment that uses only natural‑origin gases, and Toshiba aims to commercialize the products in fiscal year 2028.

GIS is used in power transmission and distribution substations. It comprises components that provide safe control of electricity flows, such as GCBs, which interrupt current in the event of system abnormalities, disconnect switches^*1 and earth switches^*2 (Figure 1). In high‑voltage substations, the core of transmission and distribution networks, GIS handles large power loads and installations tend to be large. To counter this, SF₆ gas—which offers excellent electrical performance and high stability—has been used to achieve compact equipment designs. However, SF₆ has an extremely high global warming potential (GWP) and is nearly 25,000 times more effective at trapping heat in the atmosphere than CO₂. Reducing its use is an important environmental challenge.

Toshiba is advancing the development of more environmentally compatible and sustainable transmission and distribution equipment that replaces SF₆ with natural‑origin gases, such as nitrogen, oxygen and carbon dioxide. These gases are widely available, non-hazardous and not subject to environmental regulation. Utilities and renewable energy companies worldwide are looking for their wider use.

For the verification program, Toshiba manufactured a full‑scale test model (Figure 2) using a mix of CO₂ and O₂ as an alternative to SF₆. Testing was done at Toshiba Corporate Laboratory’s Energy Systems R&D Center in Japan. For the GIS core component, the GCB, Toshiba applied a proprietary gas‑blast arc‑quenching chamber^*3 design. The internal structure of the arc‑quenching chamber was optimized for the physical characteristics of the natural‑origin gas, which enhanced interruption performance and insulation performance.

The results confirmed that the GCB satisfied design targets compliant with applicable standards for interruption and insulation. For the overall GIS, Toshiba manufactured a test model that used the same mix of natural-origin gases, and verified the performance of major components, including the disconnect switch and the earth switch. The results demonstrated that equipment that maintains compatibility with current SF₆‑based equipment, but that uses natural‑origin gases, can be realized on a practical scale.

Toshiba will use the results from the full‑scale test model in the design and testing of prototypes of commercial equipment, and aims to introduce commercial products in fiscal year 2028. Toshiba has also launched AEROXIA™^*4, a brand of transmission and distribution equipment that employs natural‑origin gases with a GWP lower than CO₂, and will continue to expand the product lineup to contribute to the decarbonization of power infrastructure and the realization of a sustainable society.

• Disconnect switch: A safety device that securely isolates a circuit under no‑load conditions (when no current is flowing) during inspection or maintenance of high‑voltage circuits, providing electrical isolation between the power source and the load side.
• Earth switch: A device that protects equipment and people by diverting leakage current to the ground.
• Arc‑quenching chamber: A core internal component of a circuit breaker that rapidly cools and extinguishes the high‑temperature arc generated between electrical contacts during current interruption, enabling quick and reliable disconnection of the electrical circuit.
• AEROXIA™: For further details, please refer to the AEROXIA™_Brandbook (PDF)(9.08MB).
  * Correction: The web link has been corrected on April 23, 2026.

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