AC Loss Characteristics of a Cylindrical High Temperature Superconductor

A cylindrical high temperature superconductor (HTS) is often used in power applications such as power transmission cables and matrix fault current limiters. In commercialization of these apparatuses, AC loss is a critical factor but not elucidated completely because of complexities in its measurement, e.g. non-uniform current distribution and phase difference between currents flowing in an individual HTS tape. We have prepared two cylindrical conductors composed of a Bi-2223 tape with different critical current density and one hollow conductor made of Bi-2212 bulk material. In this paper, the AC loss characteristics of the conductors have been experimentally investigated and numerically analysed. The results show that the measured losses for all the conductors are not dependent on both arrangements and contact positions of a voltage lead. This implies that most of loss flux is only in the conductors. The loss for the Bi-2223 conductor with high critical current density is in good agreement with the numerically calculated one based on the polygon model, whereas the loss measured for the Bi-2223 conductor with low critical current density coincides with the calculated loss from the monoblock model.