AC Loss in Each Layer of Three-Layer Twisted HTS Cable

We measured the ac losses in each layer of a three-layer twisted high-temperature superconducting cable. The currents in each layer were controlled using three power supplies and the transport current balance and phase could be varied. Longitudinal magnetic fields were produced by the transport currents in the outer layers and circumferential magnetic fields were produced in the inner layers of the cable. The amplitude and direction of the composition magnetic fields changed according to the distribution of the transport currents in each layer. The critical currents in each layer were different; hence, the ac loss in each layer could not be compared. We measured the influence of the electromagnetic conditions in a layer by varying the transport current balance in the other layers. We also transported current in the “single-phase mode” and “three-phase mode,” and measured the losses in each layer.