Nexans has been awarded a 13 million Euros turnkey contract to supply the power cables for the new Kraftwerke Linth-Limmern pumped-storage hydropower plant currently under construction in eastern Switzerland. This contract covers the design, manufacture, supply, installation, connection and commissioning of about 30 km of Extra High Voltage (EHV) cables.

Nexans will supply six 380 kV XLPE-insulated underground cables, each approx. 5 km in length, which corresponds to the length of the underground access tunnel in which they will be installed. Laid in parallel to connect the new plant to the EHV power transmission grid, these cables will comprise copper core conductors with a cross-section of 1,600 mm².

The Limmern pumped-storage project

The Limmern pumped-storage project in the Linthal Valley will utilize the proximity of two existing water holding reservoirs - the Muttsee Lake (elevation: 2,474 m; new capacity: 25 million m3 water) and the Limmernsee Lake (elevation: 1,857 m; capacity: 92 million m3 water) - by building an underground pumped-storage plant between the two lakes.

During the day, when power demand is at its peak, water will be released through the turbines of the new Limmern plant to generate electric power for the coverage of demand peaks. At night, as demand decreases, a larger amount of electric power is available on the grid, this will be used by the new Limmern plant to pump back water “upstream”, from Limmernsee into Muttsee. For these pump-and-turbine operations, the Limmern plant will be supplied with some 1 000 MW power through an underground access tunnel which is about 5 km long.

With its ability to pump back water from the lower into the higher reservoir, the plant acts like a huge rechargeable battery, using readily available night-time power to provide a very reliable and flexible power supply which can cover peak demand during the day. The same power lines, connected to the Swiss national EHV power transmission grid, will provide the electric power required to pump back water as well as exporting the power generated by the plant when it is operating in turbine mode. This connection will be provided by Nexans’ 380 kV cables.

“The experience of Nexans’ staff in Switzerland in EHV cabling projects has made it possible to meet the needs of our customer. The command of complex installation techniques in very challenging conditions was also a key requirement. With this project, Nexans once again demonstrates its leadership in the field of power infrastructure, with the capability to supply end-to-end solutions, from design to commissioning,” said Dirk Steinbrink, Managing Director of Nexans’ High Voltage Land Business Unit.