Concentric and compact connections for superconductors

Cool connections

Medium-voltage superconducting cables often use three concentric phases in a single cable to carry maximum energy in minimum space. To merge superconductors and regular cables, newly patented termination connections allow transition between cryogenic phases at -200°C and ambient networks.  

Easy does it!

Using radial geometry, we developed a single termination for all three phases that was compact and efficient. Then, we successively connected each phase within this unique accessory in an interface that fitted perfectly into the room-temperature network, making it extremely easy to integrate. 

Triple challenge

Initial studies revealed three challenges. First, we had to minimize the heat exchange between the inner part of the accessory at cryogenic temperatures and the external ambient part, despite the passage of a high current (up to 2400 amps). Secondly, to manage the contraction of ultra-cold materials and avoid thermo-mechanical stress while maintaining efficient electrical connections. And thirdly, to ensure easy fitting with other critical components. In Calais, we conducted thermal finite element studies and ran electrical tests on prototypes in cryogenic conditions to integrate the connections within a single accessory.  

Valuable grid replacements

Validation of this connection concept was carried out in 2013 in Nexans’ state-of-the-art Hanover Superconducting Competence Center using test loops to qualify a complete concentric 3-phase superconductor cable system. Superconductor systems are particularly suitable for replacing sections of congested urban networks requiring higher voltages (110 kV). They also simplify the corresponding infrastructure, reduce energy losses, and remove unsightly HV transformers, which take up precious city space. Intellectual property rights for this connection concept were filed at the beginning of 2012, and the patent delivered in early 2014.