In Aargau, a high-voltage power line is installed underground

The construction work on the "Gäbihübel" in the Bözberg / Riniken area started Thursday with the groundbreaking ceremony. The extensive work will last until the end of 2020.

The underground cabling is part of the high-voltage connection between Beznau AG and Mettlen LU. It is a bottleneck in the Swiss transmission system.

The voltage is increased from 220 to 380 kilovolts. The project aims to increase security of supply, particularly in the Zurich & Central Switzerland regions.

Currently a 6.5 kilometer section is being rebuilt between Beznau and Birr. With a length of 1.3 kilometers the maximum voltage line falls under the ground. This is a first for the national network company.

To connect the cabling to the overhead line, two overhead lines are built. There are also two transition structures that each claim the area of ​​an ice hockey field.

The total cost of the project is 34 million Swiss francs, of which 20 million Swiss francs for the cable section with the two transitional structures. The current overhead line, which runs over the settlement area of ​​Neu-Riniken, will be rebuilt.

The earth cabling project was only developed after a legal battle. The Federal Supreme Court ruled in April 2011 that a project for partial cabling had to be elaborated in the municipality of Bözberg.

Thus the community and many private individuals sat down with their question. The federal court ruled that underground cabling had become more efficient, reliable and cheaper thanks to technological advances.

Underground cable systems can also force themselves to maintain a landscape of medium or local importance. The Swiss Federal Bureau for Energy (SFOE) gave the green light for the concrete construction project in July 2016.

The underground cables are routed in two 1.5 meter wide cable tube blocks. This requires a cable trench of five meters wide and two meters deep.

From mid-2019 the underground cables will be pulled inwards, which, due to their thick insulation, are considerably heavier than above-ground cables from a overhead line. The laid twelve cables bring a total weight of 380 tonnes on the scale.

Swissgrid plans to commission the new 380 kilovolt line by the end of 2020. In 2021 the previous catenary of 220 kilovolts will be dismantled.

Earth cabling in Fricktal is not the first such project in Switzerland. The 380 kilovolt connection to the pump accumulator Nant de Drance in the Valais Alps must be constructed over a length of 1.3 kilometers at a depth of 25 to 30 meters. The necessary building permit is available.

Swissgrid developed a scientific program for the project in Fricktal in consultation with the authorities and specialized bodies. Subjects are the temperature profile in the soil in the immediate vicinity and in the surrounding area and the magnetic fields at different loads on the lines.

Earth wiring in the extra high-voltage grid is "an option" and "not a panacea," Swissgrid writes in a brochure. Less than one percent of the total Swiss electricity grid, measured on the length of the lines, was built as aboveground lines. (SDA)

Posted on 23.08.2018 | Updated 2 minutes ago

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