In June, RWE Transportnetz Strom GmbH (Dortmund, Germany) gave the go-ahead for the installation of a gas-insulated extra-high-voltage (EHV) transmission line (GIL) at Frankfurt Airport. Siemens Energy (www.siemens.com) will start to lay an approximately 1-km (0.62-mile)-long EHV overhead line as a buried GIL.

The 380-kV transformer substation has already been constructed to a compact design using gas-insulated technology for the planned runway in the northwest area of the airport. The 380-kV overhead lines routed to this substation have to be laid underground for the last kilometer in order not to disturb air traffic operations. RWE Transportnetz Strom will implement this line section with two systems in the form of buried 380-kV GILs. Each system will have a maximum transmission capacity of 1800 MVA. The GIL link comprising two three-tube units is scheduled to be connected to the supply system in the spring of 2010.