Transport AC losses analysis of twisted quasi-isotropic conductor

•AC losses of twisted quasi-isotropic conductor were measured, calculated and analyzed.•3D simulation based on the T-A formulation was adopted.•Minimum twisted pitch length of the quasi-isotropic conductor was obtained.•Reduction of transport AC loss of the quasi-isotropic conductor was discussed. The second-generation (2 G) high temperature superconducting (HTS) conductor is widely used in high-field magnets and power transmission cables and its AC loss is one of the main obstacles. This paper mainly analyzed AC losses of twisted quasi-isotropic conductor stacked by 2 G HTS tapes and copper tapes by simulation and experimental methods at 77 K. A twisting apparatus was designed and manufactured for fixing and twisting the quasi-isotropic conductor accurately and the transport AC losses of the conductor with different twisted angle were measured by four-probe method under different frequencies. Meanwhile, a 3D simulation based on the T-A formulation was adopted to handle simulation challenges of HTS tapes with high aspect ratio and overall understand AC losses on the twisted quasi-isotropic conductor. Simulation results are in good agreement with the measured ones and the current distribution in the HTS tapes was investigated in detail. The results are helpful for fully understanding transport AC losses characteristics of twisted quasi-isotropic conductor.