On 21 August, the new transformer in Laufenburg was successfully put into operation. It is part of the «Strategic Grid 2025» and plays a key role in the Swiss transmission grid.
The new transformer connects the 380 kV and 220 kV grid level and increases the capacity of the Laufenburg substation from 600 to 800 MVA. As an important grid element, it ensures the future supply of electricity to the Swiss population, even in the event of increased electricity consumption.
The transformer consists of four poles, three active and one reserve pole. In the event of a fault, the reserve pole can replace the defective pole without time-consuming transfer. What normally takes weeks, can be performed in just a few days in Laufenburg. An active pole is replaced with the reserve pole every five years. This increases the transformer’s service life by a third, from around 45 years to at least 60 years.
The safety precautions comply with the highest standard. The surrounding concrete walls are equipped with a sprinkler system, which cools the hull of the poles in the event of a fire and first of all prevents fires from breaking out. The water is provided by a specifically constructed reservoir in the substation with a capacity of around 800,000 litres. A retention pond is located under the four poles, which collects any leaking transformer oil in case of an emergency. The fire-fighting system is triggered automatically in case of a fire.
The new transformer replaces the old one, which has been in use since 1966. To keep the opening time of the transformation to a minimum, the replacement essentially took place while the old transformer was still in use. The old transformer was dismantled after 53 years of service.
Two additional 800 MVA transformers will be installed in Chippis and Mühleberg as part of the «Strategic Grid 2025».