Swissgrid, owner of the Swiss high-voltage grid, is celebrating a premiere: For the first time, Swissgrid will be laying a longer section of a high-voltage line at a length of 1.3 kilometers underground. The partial cabling project is technically challenging. The goal is to increase the voltage between Beznau (AG) and Mettlen (LU) from 220 to 380 kilovolts. Swissgrid is thus implementing another section for the Strategic Network 2025.
With the cable laying of a total of 12 cables into two pipe blocks, Brugg Cables will be faced with a logistically and technically demanding task from the middle of 2019: Due to their thick insulation, cables are considerably heavier than conductor cables of an overhead line. The total cable weight is around 380 tons.
The cable type XDRCU-ALT 1x2500ALmm2 380 / 220kV with aluminum in the cable ladder and copper in the shield produced by Brugg Cables convinced Swissgrid thanks to its low weight and high electrical transmission capability. To connect the cable lines laid in the ground with the overhead line connections, two transitional structures are built, which occupy approximately the area of an ice hockey field and are about 25m high.
At the Gäbihübel, it becomes apparent what effects the cable laying of a section of a 380 kV extra-high voltage power line has on the landscape and the environment, what the costs are and what are the challenges of construction, operation and maintenance. Swissgrid is therefore providing scientific support for the project. From the beginning of 2019, a visitor center will present the opportunities and challenges of underground cabling to the public in a transparent and objective manner.
The commissioning of the new 380 kV line is planned by the end of 2020. The existing 220 kV overhead line, which runs through the Neu-Riniken and Hafen areas, will be dismantled 2021. With this turn-key order, Brugg Cables has created an ideal reference for further network expansion opportunities in Switzerland.