Development of Nb-Ti and Nb₃Sn Superconducting Cables for Power Apparatus

Abstract

R & D on Nb-Ti and Nb₃Sn superconducting cables for AC use has been carried out toward power applications. As for Nb-Ti conductors, three types of stranded cables were developed aiming at armature winding of generators, shunt reactors/transformers and fault current limiters. Structures of stranded cables were optimized based on the AC losses and the AC quench current (Iq) degradation in the applied magnetic field ranges of each apparatus. As a result, 10kA_rms in Iq and 10kW/m³ in AC losses (0.5T, 51Hz) were achieved. As for Nb₃Sn cables, effective improvement of both AC losses and Iq were made by addition of magnetic elements in the matrix and filaments and by optimizing the filament diameter and spacing. Moreover, we utilized the knowledge of Nb-Ti stranded cables in establishment of Nb₃Sn cable structures. As a result, 5kA_rms in Iq and 10kW/m³ in AC losses (0.5T, 51Hz) were achieved.