Tri-Axial Cable Terminations for 1.3- and 3-kA HTS Cables

Abstract

The Southwire/ORNL team has conceived, designed, built, and tested a 5‐m, three‐phase, tri‐axial cable with terminations. The cable has three concentric superconducting phases made of BSCCO‐2223 HTS tapes, separated by layers of cold‐dielectric tape with a copper braid as the grounding shield. The cable is enclosed in a flexible cryostat. Cooling of the cable and terminations is achieved by liquid nitrogen flowing through the annulus between the cable and the cryostat. A challenging analysis and design issue was development and implementation of an insulator material between the concentric phases with high enough thermal conductivity to meet temperature gradient requirements and acceptable mechanical and electrical performance. The resulting 3‐phase, cold dielectric, cable and termination design is nearly as compact as the single‐phase, co‐axial design developed previously by Southwire/ORNL, and it represents the highest cable current density achievable in an electric ac power cable. This paper presents results from operation of the 1.3‐kA root‐mean‐square (rms) phase current termination and design changes required to scale to 3‐kA rms phase current.