TRANSFORMER CURRENT-LIMITING METHOD USING SUPERCONDUCTING MEMBRANE AND CURRENT-LIMITING DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a method to reduce the use of current-limiting elements as possible which use expensive large-area superconducting membranes, by performing high voltage electrical insulation at ordinary temperature to solve the problem of high voltage electrical insulation in a cryogenic condition and thermal load on the superconducting membrane elements of a superconducting current-limiting device of SN transfer resistance. SOLUTION: A transformer (of normal conductivity) is adopted to avoid the electrical insulation problem at high voltage in a cryogenic condition, and the primary side is set to a high voltage and the secondary side is set to a low voltage. The current-limiting element of high temperature superconducting oxide membrane having a high critical current density and a high resistivity at normal conductivity, manufactured on a board of an insulating body having a large area is connected to the secondary side of the transformer. Since thermal load on the superconducting element can be reduced by allowing the primary coil of the transformer share at ordinary temperature the high voltage electrical insulation and the superconducting current- limiting element share the control function of low voltage/large current on the secondary side, the current-limiting device which can be useful for a high voltage can be provided at low costs.