Green Substitution Accelerates: Vacuum Interruption Combined With Eco-Friendly Gas Becomes A New Route For High-Voltage Switchgear - News

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How should equipment operating at high voltage levels be replaced?

A fluorinated gas once widely used in power switchgear, with a greenhouse effect about twenty thousand times that of carbon dioxide, is facing increasingly strict restrictions. The EU has stipulated that starting in 2026, medium-voltage switchgear at 24 kV and below may no longer use this gas. How to replace it in higher-voltage equipment has become an issue the industry is working to solve.

Cut off the current using a vacuum tube

A currently prominent approach is to use a vacuum tube to interrupt current, while filling the exterior with dry air or a gas with a very low greenhouse effect to provide insulation. This avoids the original fluorinated gas while leveraging the vacuum tube's mature interrupting capability and long service life. Some domestic companies have already produced 252 kV enclosed switchgear based on this approach, raising the fault-current interruption capability from 40 kA to 50 kA and passing multiple rigorous assessments. The low-greenhouse-effect mixed gas used has a greenhouse effect more than 98% lower than the original gas; dry air has no greenhouse effect at all, but its insulating capability is weaker and must be compensated for by increasing gas pressure or enlarging equipment dimensions.

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It should be noted that long-term operating experience with this new route at higher voltage levels is still being accumulated, and gas purity and sealing reliability are key engineering concerns. From the trend perspective, using vacuum tubes to interrupt current combined with low-greenhouse-effect gas insulation has moved from demonstration applications to productisation and has become an important direction for the green transformation of power switchgear.