Development and Test Results of HTS Windings for Superconducting Transformer With 1 MVA Rated Power

We developed a method to combine parallel superconducting HTS tapes to a current carrying element with high current and uniform current distribution among strands at ac mode. The current carrying elements are made of several parallel HTS tapes placed side-by-side on a round mandrel. The test of the small model made of five parallel 2G HTS tapes confirmed the idea. The method was implemented for 10/0.4 kV, 1 MVA power transformer. For both low and high voltage windings, we used 12 mm Amperium tapes from American Superconductor Co. For low-voltage winding 19 parallel tapes were wound on four mandrels and connected in series. High-voltage winding was wound with a single 12 mm tape. The assembled windings of each phase were tested at liquid nitrogen temperature without iron yoke. AC losses were measured in low-voltage winding at two modes: when high voltage winding was either shortened or open. In this paper, we present the details of current carrying element development and test, 1 MVA transformers winding designs and test results.