Tests of 5-m Long Triaxial HTS Cables

摘要

Following the positive results of a 1.5-m long prototype cable, the Ultera and Oak Ridge National Laboratory (ORNL) team built and tested a 5-m triaxial cable rated at 1.3-kA rms, 15-kV ac. The three concentric superconducting phases are made of BSCCO-2223 high-temperature superconducting (HTS) tapes, separated by layers of cold-dielectric tapes. A copper braid is added as the grounding shield on the outside of the three active phases. To facilitate the calorimetric ac loss measurement, the cable was cooled by liquid nitrogen flowing in the annulus between the cable and the cryostat only. Tests of this cable were performed at temperatures ranging from 76 to 84 K. AC loss data reconfirmed the previous gratifying result on the 1.5-m prototype cable that the total three-phase loss is approximately the sum of the calculated ac losses of the three separate phases. No additional loss is due to possible coupling among the three phases. This and other test results of the 5-m, 1.3 kA triaxial cable are reported here. The next step in the project is to build and install a triaxial cable rated at 3-kA rms, 13-kV ac at a utility site. A single-phase 3-kA cable prototype was also built and tested for use as the most demanding inner phase of the triaxial cable.