A world first for rail safety: SIGMAPHI collaborates with NEXANS and SNCF RESEAU on a superconducting innovation

A major technological breakthrough is enhancing the safety and reliability of the French rail network. In Belfort, in the Bourgogne-Franche-Comté region, a new system that is unique in the world is being installed: a superconducting current limiter (SFCL), the result of a partnership between Nexans, a leader in the design and manufacture of cable systems and services as well as in the development of superconducting technologies, and SNCF Réseau, the national rail network operator. SIGMAPHI, an expert in electromagnetic solutions, has contributed its expertise to this major project by manufacturing superconducting coils for current limiters.

Innovation in the service of safety

The purpose of the superconducting current limiter is to protect railway lines from short circuits that may occur on the power supply network. Thanks to its fully autonomous operation, this system is capable of absorbing current surges, thus preventing power cuts and disruptions to train traffic.

This is a world first in the railway sector, which should improve network availability, particularly on the line between Belfort and Delle, up to the Swiss border.

For this strategic project, Sigmaphi was asked to manufacture a central element of the system: the coils. These are a complex assembly of 30 wafers in a compact stack to form the final heart of the device.
This work, carried out over several months, enabled great precision, particularly in the production of the windings and the soldering at the ends of the coils.

This type of coil is specially designed to not generate a magnetic field—a crucial criterion, as they must only conduct current without disturbing the surrounding electrical systems.
Occasional technical visits to the project, including with the Nexans and SNCF representatives, were held to understand the manufacturing process and tour the SIGMAPHI workshop.

A collaboration of excellence
This cooperation between Nexans, SNCF Réseau, and Sigmaphi illustrates how synergy between major groups and specialized companies can lead to high-impact solutions. The installation of the SFCL in Belfort marks an important step in the modernization and security of the railway network, by relying on cutting-edge technologies such as superconductivity.