High-Temperature Superconducting Cable Design Based on Individual Insulated Conductors

The idea of insulating individual high-temperature superconducting (HTS) tapes was explored as a dielectric design to reduce the risk and complexity of HTS cable manufacturing. Applying insulation on individual HTS tapes is amenable to continuous manufacturing processes and opens up material choices for the insulation. In this study, heat shrink insulation was selected as the material choice for exploring the possibility of this design philosophy because of its commercial availability in multiple thicknesses. A systematic set of selection criteria was developed for the selection of appropriate heat shrink for given HTS tape dimensions. The cryogenic dielectric characteristics of insulated HTS tapes were evaluated both in liquid nitrogen and gaseous helium environments at 77 K. Dielectric characteristics of tapes with a single layer of thicker insulation were compared with those insulated using multiple layers of thinner insulation to evaluate the relative merits of each method. Several model power cables were fabricated using the PET insulated tapes, and their dielectric behavior was evaluated at 77 K in gaseous helium environment. The results suggest that the explored method is useful for HTS power cables operating at low voltages (<1,000 V) primarily due to the limitation on achieving thick insulation with high quality using heat shrink tubing. The suitable processes of insulating longer lengths of samples with additional dielectric benefits are discussed.