Preliminary tests on a superconducting power transformer

Test results for a 50-Hz single-phase power superconducting transformer are presented and discussed. The near-ambient-temperature iron core, of conventional shape, is situated in a fiber-glass reinforced-composite inner vessel which is vacuum insulated from the He bath. The iron core is cooled by an inner channel. Inter-leaved low-voltage and high-voltage windings are wound around the inner vessel by halved formers and cooled by natural convection in a 4.21 K He bath. The tests demonstrated construction feasibility (showing considerable weight reduction compared with nonsuperconducting designs); increased efficiency for power levels of about 1 MVA; and fault current strongly limited by the high value of conductor matrix resistivity.