AC loss characteristics of a hex-cable in an azimuthal external AC magnetic field

Recently, power transmission cables made of a high temperature superconductor (HTS) are being developed, showing progress in field tests on a power network of distribution level. The HTS power cable consists of a conductor and a shield, which are composed of dozens of HTS tapes. In addition, the HTS cable with a large current capacity has a multi-layered structure in both the conductor and the shield. In such a complicated HTS cable with a multi-layered structure, the AC loss estimation is very difficult and thus not cleared yet. In this study, a hex-cable sample was prepared by arranging six Bi-2223(Bi2Sr2Ca2Cu3O10) tapes on the surface of a normal copper-rod in order to experimentally investigate the AC loss characteristics of an HTS cable. The AC loss characteristics of the Bi-2223 tape in the hex-cable were estimated in different transport modes of the tape. The AC loss characteristics of the hex-cable were also examined in different cable transport modes in order to experimentally simulate the various transport situations of the conductor and the shield in an actual HTS cable. The measured AC loss of Bi-2223 tape in the hex-cable strongly depends on the transport mode. In particular, the measured AC losses for the simultaneous mode increase as the arrangement of tapes approaches a polygonal shape. The measured AC loss when the current of the same direction flows in the hex-cable and the copper-rod is about two times larger than the transport loss. On the contrary, it is almost half of the transport loss for the current flowing in the opposite direction, especially in the region of high currents.