Preparation and Experimental Investigation of Heavy-Current Transposed HTS Conductors

Various high-temperature superconductor (HTS) devices (transformers, electrical machines, accelerator magnets, power transmission lines, current leads, etc.) need operating currents that many times exceed single HTS tapes current capacity. Conductors made of many transposed HTS tapes wound in parallel onto several mm-diameter flexible formers can be made of modern 2G tapes. Such conductors combine large operating currents, low power losses, and flexibility. Our electrical and mechanical properties measurements of various manufacturers´ tapes showed the possibility to make such conductors. The HTS tapes (up to 16) were wound helically onto several mm-diameter flexible formers made of twisted bundle consisted of 3000 stainless steel wires of 0.1 mm diameter. The V-I curves at dc in external magnetic field up to 0.6 T and the V-I curves and ac losses at 50 Hz in self field and in the synchronous background field were measured at different cooling conditions. For all cable samples the current capacities were proportional to the number of tapes.