HTS CroCo - A Strand for High Direct Current Applications

High temperature superconductors (HTS) are discussed as energy-efficient solutions for applications needing high direct currents beyond 10 kA e.g. for large high-field magnets or bus bar systems in industrial electrolysis plants. A number of high-current cable concepts based on REBCO tapes were developed such as the Roebel cable, co-axially wound tapes and several stacked-tape arrangements, among them the HTS CrossConductor (HTS CroCo), a stacked-tape conductor with high current density developed at KIT. In this manuscript, the experimental test of a high DC demonstrator, termed Supra-DC-Cable, made from twelve HTS CroCo strands is presented. The demonstrator was tested successfully at T = 77 K, reaching the expected critical current of 33 kA at 77 K and even for a constant-current operation at 36 kA for more than 30 minutes limited by the copper connections, not the superconducting cable. Currents and voltages were measured in all twelve strands individually during the parallel operation in the cable. These measured data allow the experimental validation of the modelled current distribution, based on the individual characterization of the twelve strands.