Comparison between insulated and NI layer-wound ReBCO coils during transients

In this work, the results of a broad experimental investigation carried out on two layer-wound High Temperature Superconducting (HTS) coils are presented, adopting an experimental set-up that allows a consistent comparison between multiple configurations. To focus on a few design choices only, the coils are wound with the same geometry and using the same tape. One of the windings includes electrical insulation between layers, while the other does not. Moreover, since the proposed set-up allows feeding the layers separately, the latter can be connected either in series or in parallel. Thus, inductive and non-inductive combinations can be efficiently tested without the need to unwind or rewind the tape around the mandrel. The voltage signals acquired, and the corresponding ac losses, obtained during ac tests in liquid nitrogen are compared in different working conditions, providing qualitative explanations of the experimental data in the different winding combinations.