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Environmentally friendly technology in the Virkkala substation

The substation in the Virkkala area of Lohja is pioneering Fingrid’s substation renewal efforts – it is the first substation to operate without sulphur hexafluoride (SF6 dielectric gas) in its switchgear. The project is groundbreaking on an international scale, as it is Siemens Energy Europe’s largest delivery of SF6-free technology to date.

There is less public awareness of SF6 as a greenhouse gas in comparison with carbon dioxide. SF6 is widely used in power systems thanks to its excellent dielectric properties. However, it is a potent greenhouse gas, and special measures must be taken to prevent it from being released into the atmosphere. If SF6 is released into the air, the climate damage is thousands of times worse than with carbon dioxide.

“Only certified professionals are permitted to handle SF6. Effective monitoring enables even minor leaks to be detected immediately, and we have succeeded in minimising leaks,” says Daniel Kuosa, Construction Manager at Fingrid.

The process of eradicating SF6 dielectric gas from the energy sector is still in its infancy. The sector has long been seeking substitutes for the gas, but it is only in recent years that new substitutes have been successfully developed. These solutions will enable switchgear containing SF6 gas to be phased out systematically.

The solution in use in Virkkala is the Siemens Blue GIS technology, which uses clean air as a dielectric substance. The contract covers GIS switchgear consisting of ten bays with the new technology, making it Siemens Europe’s largest Blue GIS delivery to date.

Fingrid has drawn up a roadmap for phasing out environmentally harmful SF6 dielectric gas whenever substations are modernised. The Virkkala substation is the first implementation on the roadmap.

What is SF6?

  • The first gas-insulated switchgear (GIS) for use in high-voltage substations came onto the market in the 1960s, along with SF6 dielectric gas.
  • A very effective, permanent dielectric gas used in switchgear on the electricity transmission grid.
  • A potent greenhouse gas approximately 23,500 times more damaging than carbon dioxide if it is released into the air.

What does the Virkkala substation use instead of SF6?

  • Siemens Blue GIS technology
  • The dielectric substance is clean air.
  • The old Virkkala substation contained 2,500 kg of SF6 gas. The new one contains 0 kg. 2,500 kg of SF6 gas is equivalent to 57,000 tonnes of carbon dioxide.


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