Calorimetric AC Loss Measurements in Multilayer Triaxial 2G HTS Power Cable

Triaxial HTS AC power cables, that incorporates three HTS phases wound around a single core within a single cable is considering the optimal solution for low and medium voltages power cables. To increase the power transmitted by a triaxial cable with keeping a cable diameter small enough, it is possible to increase an operation current by using a multilayer structure in each phase of a cable. This task demands a complicated optimization analysis to provide the proper current distribution between phases and tape layers in each phase. Recently, we developed and tested the triaxial cable where each phases had two layers made of 2G HTS tapes. The cable demonstrated all parameters coincided with the calculated ones. With an outer diameter of ∼24 mm, this is the most compact triaxial HTS power cable manufactured and tested up to date with currents up to ∼4 kA per phase. Measurement of AC losses by our standard digital electrical method turned out to be difficult for this cable. It was due to the problems by taking into account the distribution and phase shift of currents between all layers of the cable. To perform AC loss measurements, we have developed a test set-up for measuring losses by the calorimetric method. In this paper, we present the details of the test set-up and results of calorimetric measurements AC losses at different frequencies in the triaxial HTS cable with two layers per phase. Calculated AC losses by standard models are presented also and compared with the measured ones.