Underground aluminium tube carries 380,000 volts
06.07.09 -The building of a new runway at Frankfurt Airport means changes are having to be made to an extra-high voltage transmission line that crosses the planned approach path. Experts from Siemens and the electricity company RWE will therefore lay a one-kilometre-long section of the 380,000-volt line underground. Aluminium has been chosen as the conductor material.
This will be the world’s first commercially installed gas-isolated extra-high voltage line so the companies in the consortium had to develop the new technology required.
The current-carrying conductor is enclosed in a casing tube, with the interspace filled with an insulating gas. The conductor itself is in the form of an aluminium tube. High-purity aluminium is characterised by excellent electrical conductivity and at the same time is also readily formable – two properties to which particular importance is attached for this specific application.
The go-ahead has now been given for the seven-million-euro project. Excavators have been digging a 10-metre wide trench for the tube since April. The new transmission line is scheduled to be connected to the Kelsterbach transformer substation in the spring of 2010. Once this approach has proven itself in practice, other transmission lines using this technology will doubtless follow.