PURPOSE: To improve current limiting performance and avoid the local fusion of a superconductor by a method wherein the cross-sectional areas of a plurality of the reduced cross-section parts of the superconductor are approximately identical.
CONSTITUTION: A plurality of reduced cross-section parts 1a are provided in a superconductor 1 and the cross-sectional areas of the reduced cross-section parts 1a are approximately identical. If an excessive current, for instance a short-circuit current, is applied to the superconductor 1, all the reduced cross-section parts 1a are first quenched almost simultaneously and the short-circuit current is substantially limited. Then heat generated in the reduced cross-section parts 1a is transmitted to non-reduced cross-section parts and the non-reduced cross-section parts are also quenched and the excessive current is further limited. As a plurality of the reduced cross-section parts 1a are quenched almost simultaneously, the excessive current is substantially limited and the fusion of the reduced cross-section parts 1a is avoided. It is to be noted that, as a plurality of the reduced cross-section parts of the superconductor are simultaneously quenched when the excessive current is applied, an excessive voltage accompanying a current limiting operation is increased but it can be suppressed by connecting a surge absorber in parallel with the current limiting device.
HAYASHI TATSUYA
UCHIKAWA HIDEFUSA
MATSUNO SHIGERU
KINOUCHI SHINICHI
