Design and Operating Characteristics of Superconducting Transformer with Simple Configuration

A 40kVA three phase superconducting transformer has been developed and tested. In order to simplify its configuration, whole the transformer including windings and iron core was immersed in liquid helium. Reducing iron losses is the key to design such type of superconducting transformer. Iron loss characteristics of three types of core materials were measured under liquid nitrogen temperature. Among them, ultra fine crystallized metal (FINEMET) showed excellent low iron loss characteristics. Superconducting transformer made of such core and high Tc superconducting ac wire, whose whole the structure is cooled by liquid nitrogen, is very promising alternative.