The last day of February 2025 went down in history as the 110kV main switchgear M050 in Kilpilahti ended its long and significant life cycle, becoming de-energized, awaiting recycling. M050 was an integral part of the development and electricity supply of the Kilpilahti industrial area for more than 50 years – it not only supplied electricity, but it also played a role in laying the foundation for the area’s industrial growth and development.
The story of the M050 began in the early 1970s, when an ethylene plant was planned next to the refinery, which required large amounts of steam. At the same time, the refinery’s electricity supply had relied on a 110kV village line from Nurmijärvi, which was susceptible to disturbances. As a solution to this challenge, a new 110kV switch station, M050, was built, which became part of the electricity network solutions of Kilpilahti’s industry.
M050 operated reliably for decades, but in the mid-1980s, an unfortunate event occurred that triggered an unprecedented electricity network development project in Kilpilahti. A fault in the anti condensation heater in the switchyard cabinet led to a short circuit that cut off the 110kV supply to the refinery area. Although backup power systems had been designed as safeguards, they did not function as expected. However, this disruption led to significant investments and improvements to the electricity grid, most of which were carried out by Neste Engineering and IVO International.
The construction of the new electricity supply system was quickly initiated. Redundant backup diesel and UPS systems were installed for the refinery control room, and a new, diesel-backed medium-voltage reserve power distribution network was built in Kilpilahti. In addition, significant changes were made to the area’s 110kV radial network, forming a loop network that improved the area’s electricity supply and preparedness for possible disturbances.
In 1994, during a summer thunderstorm, M050 once again reminded us of how vulnerable the electricity grid can be. When lightning struck the outgoing line poles of M050, the entire 110kV network in Kilpilahti was momentarily de-energized – except for M050 and the power plant. The event led to improvements in which earthing was strengthened and preparedness for disturbances in the electricity network was further improved.
At the turn of the millennium, the renewal of the substation became necessary, and a replacement for M050 was sought. A project to build a new gas-insulated substation was launched, and in 2015, an investment decision was made to construct M150. This project also marked the first investment for Aurora Kilpilahti’s new distribution network company. The schedule was tight, as the new power plant’s main transformers needed to be connected by May 1, 2017—a goal that was successfully achieved. The life cycle of M050 was extended for another seven years, after which it only served as a line connection to the main transformers of the old power plant.
M050 has been an essential part of the development of the electricity supply in Kilpilahti and the industrial operations of the area for more than fifty years. Its role as a safeguard and enabler of the areas electricity network development cannot be forgotten. Even though the M050 switchyard will be demolished, and the land area will be freed up for other uses, its memory will live on as part of the history of Kilpilahti’s development.
We extend our gratitude to M050 for all the years it served the Kilpilahti industrial area and its businesses. We hope that in the future, this site—where M050’s story now comes to an end—will continue to evolve, bringing new energy and innovation, just as M050 once did.
Jyrki Havukainen
Site Manager, Aurora Kilpilahti Oy
