Lo-Sag™ composite core cables deliver electrifying performance
When RTE, France's electricity transmission system operator wanted to modernize their steel-reinforced overhead lines dating from 1929, Nexans proposed Lo-Sag™ overhead composite core cables. They can be strung on existing tower infrastructure, while low sag protects against blackouts.
Lo-Sag™ is lighter, stronger and can tolerate higher peak load temperatures than predecessors, which means more reliable power for consumers. A kilometer-long three-phase 90 kV line was installed in west-central France, a first for Europe that may set a precedent for future upgrades.
Researching high and low
NRCs have been working on carbon-fiber core conductors for years, and developed an in-house resin to produce 7mm cores. Original focus was on high-temperature (≤190°C) cables with high breaking load that would reduce dangerous sag and thus the number and height of pylons for broad spans (e.g. rivers and valleys). We soon perceived a need for a lower temperature cable as well (≤80°C). The RTE trial allowed us to design a new smaller version, then fine-tune the production chain from supplier to process, and fully qualify strength-members, conductors and accessories.
Lo-Sag™ was a cooperative achievement between NRC Lens/Lyon and Clichy in France and the Walloon region in Belgium. The 4.6mm composite strength member of epoxy resin and carbon fibers encased in a soldered aluminum tube was made by Hanover (Gm), and the compact AERO-Z® interlocking design was produced by Elouges (Belg). Specialists in overhead accessories were also implicated in the project. After qualification, the next step is aging tests (thermo-mechanical, wind vibration, UV, ozone, water, etc.) to assure the viability of a new overhead cable that may soon enhance European sky lines.
"In five short months, we met RTE's request for a comprehensive field trial."