Expansion of the European energy grid

Amprion and the Belgian transmission system operator Elia built the first direct power connection between Germany and Belgium. The approximately 90 km long DC underground cable line is called ALEGrO (Aachen Liège Electricity Grid Overlay) and was included in the list of PCI projects (Projects of Common Interest) of the European Union. Amprion expanded the power grid right up to the end using egeplast protective conduits for high-voltage cables.

As part of the expansion of the European energy network, a DC underground cable line has been built since October 2018. For this purpose, a 320 kV connection from Oberzier (Germany) to Liège (Belgium) was established by November 2020. Network operator Amprion uses the high-temperature resistant egeplast Power Protect with a low-friction and abrasion-resistant light inner layer. During the installation of a conduit system for a 320 kV cable from Oberzier to the Belgian border, the laying was carried out by the AAA consortium with the companies Klaus Stewering (Borken), Heitkamp & Hülscher (Stadtlohn), Ulrich Bogenstahl (Legden) and RN Rohrleitungsbau Niederrhein (Krefeld). Network operator Elia was responsible for the expansion of the route on the Belgian side.

Of the approximately 90 km, about 40 km are on the German side. These were laid using open-trench (pipeline trench) and trenchless (HDD, pipe jacking) construction methods. The power system consists of two parallel laid cable protection pipes.

30 km of these were installed using open-trench construction. For open-trench laying, the egeplast Power Protect with a push-fit socket system in the dimension 250 x 11.4 mm was used for straight route sections. For curved sections, the 250 x 11.4 mm pipe is used in combination with a High-T PE electrofusion coupler.

It is a protective pipe for high and extra-high voltage cables that features increased thermal stability to withstand high thermal stresses. Excellent fitting accuracy during the production of the socket connections enables easy handling and achieves high laying speeds. The inspection-friendly light inner layer is low-friction and abrasion-resistant, thus offering optimal conditions for cable pulling.

“With the selected construction method, installation rates of up to 100 m in a combined run, i.e. 18 lengths per day, could be achieved. A positive aspect during construction was the very easy and fast assembly of the pipe couplers, where the factory-applied insertion depth marking proved to be very helpful,” explains Manuel Schneidereit, senior site manager of the Amprion ALEGrO Aachen (AAA) consortium. The long coupler design offers increased safety.

The crossings under motorways and ICE lines were carried out using the pipe ramming method. The drilling lengths were up to 80 m at a depth of up to 8 m. A 320 kV cable is used for the installed cable system and is pulled into the cable protection conduit system. The aim is to achieve pulling lengths of up to 1,140 m.

All necessary accessory components were supplied by egeplast as the system provider – including double push-fit couplers (long version), transition pieces, electrofusion couplers, end caps, coupler covers, and rental tools (internal bead removers and butt fusion machines).