RTE international joins Swissgrid in a feasibility study and the unwinding of a live Optical Ground Wire (OPGW).

RTE international has provided its expertise by defining the feasibility of unwinding a live working OPGW and assisting in the implementation of this project.

This study was entrusted to RTE international as part of the ASR project, “Partial Burial of 220kV Overhead Lines Circuits 1&2 Foretaille-Verbois”. This ASR project included the burial of 5km of cables between the N01 motorway and Geneva airport, as well as the replacement of 6km of ground wire with optical fibre at the Verbois substation. Before, the overhead section did not have a telecom circuit, quartz or fibre. It was therefore necessary to install a new cable with integrated optical fibres (OPGW – Optical Ground Wire).

The installation of the fibre will allow :

• The extension of the Swissgrid telecommunication network
• The installation of differential protection devices to monitor the overhead and underground links in the event of a fault.

However, the electrical context of the region is complex due to its proximity to the city of Geneva and it is therefore not possible to use conventional methods to unwind the OPGW.

It is therefore in this context that RTE international provided expertise in the field of live working to enable the unwinding of this OPGW, without weakening the power supply to the city of Geneva.

The first stage of this project consisted of a feasibility study provided by RTE international, which confirmed that it is possible to unwind the OPGW cable while maintaining a live circuit. RTE international then proposed a methodology adapted to the terrain and the structure, as well as safety measures and equipment to be respected in order to carry out the work.

Today, the work has been completed and the OPGW cable has been successfully unwound.