With the filling of the transformers, Electrical Oil Services (EOS) is contributing to an important European energy infrastructure project. The Celtic Interconnector power link connects Ireland's electricity grid directly to the European mainland for the first time, strengthening security of supply, grid expansion and the integration of renewable energies.
"We are proud to be part of the Celtic Interconnector project and to contribute to the development of a secure and sustainable energy infrastructure in Europe. Our commitment to this project demonstrates that EOS is a reliable partner for complex large-scale projects."
– Kilian Gerbl, Managing Director of Electrical Oil Services
Hamburg, 15. December 2025 – Electrical Oil Services (EOS), a leading provider of transformer oil services, has successfully filled four large transformers with 75,000 litres of insulating oil each as part of the Celtic Interconnector project. This measure supports the first direct 575 km electricity connection between Ireland and the European mainland and contributes to improving security of supply and the integration of renewable energies.
The transformers were filled at a substation in Brittany, France. Three complete oil circulations were carried out for each transformer, and a vacuum time of over 48 hours was maintained to completely remove moisture and gases from the oil. This optimises the electrical insulation properties of the transformers during subsequent operation.
Kilian Gerbl, Managing Director of Electrical Oil Services: “We are proud to be part of the Celtic Interconnector project and to support the development of a secure and sustainable energy infrastructure in Europe with our work. Our commitment has demonstrated that EOS is a reliable partner for complex large-scale projects.”
Celtic Interconnector – a European energy project
The Celtic Interconnector project is a collaboration between the Irish electricity grid operator EirGrid and its French counterpart Réseau de Transport d'Électricité (RTE). It comprises a 575-kilometre high-voltage direct current (HVDC) transmission line, around 500 kilometres of which run through the Celtic Sea. Once completed, the connection will have a capacity of 700 megawatts, which is equivalent to supplying around 450,000 households. Commissioning is planned for 2026
Siemens Energy has been commissioned to build the converter stations in Ireland and France, while French cable manufacturer Nexans will lay the cable. Christof Industries from Graz is responsible for installing the transformers and has contracted Electrical Oil Services to fill them.
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Electrical Oil Services (EOS) is contributing to an important European energy infrastructure project, the Celtic Interconnector project, by filling four new large transformers. © alfotokunst |
About Electrical Oil Services (EOS)
Electrical Oil Services (EOS) is a company of Haltermann Carless and a leading supplier of new and reprocessed insulating oil and related services in Europe. EOS specialists have decades of experience in the processing and marketing of insulating oil and provide both large and small customers in the power supply industry with tailor-made solutions. These include all preventive insulating oil services and transformer maintenance – from vacuum filling for new transformers and insulating oil testing in our own laboratories to mobile oil processing and regeneration and the collection of waste oil.
More information: www.electricaloilservices.com
About Haltermann Carless - Pioneers in hydrocarbons since 1859
Haltermann Carless is a leading international supplier of high-value hydrocarbon solutions in Mobility, Life Science, Industrial and Energy. The company develops tailor-made products using advanced technologies, exploring new feedstock sources, and collaborating with business partners, research institutes, and universities. The portfolio includes Performance Fuels, Solvents, Pentanes, Middle Distillates as well as Energy Products & Services. As one of the oldest chemical companies in the world, Haltermann Carless continues its legacy with a global team of 500 employees across nine locations and production sites in Germany, France, the UK, and USA. The commitment to sustainability and responsible business practices is recognised through multiple certifications, including the EcoVadis Gold award, ISCC EU and ISCC PLUS and the prestigious FIA Three-Star Environmental Accreditation.
More information: www.haltermann-carless.com
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