Abstract
By using the developed 6, 600V/210V, 100kVA hybrid-type superconducting transformer, a short-circuit test is carried out. Excessive ohmic heating gave damage in the superconducting low-voltage winding after a superconducting-normal transition (quenching) was induced and resulted in wire ruptures at three points. The superconducting wire was partially colored in brown in 1.3 turns including those ruptured points. The metallic composition in the cross-section of the superconducting wire is observed by a SEM and an X-ray microanalyzer. The critical quenching currents of the short samples picked out of the superconducting winding are also measured. The following results are derived: (1) The arrangements of metallic composition in the superconducting wire are distorted around the ruptured point, at which the wire temperature is estimated to have reached higher than 900°C, (2) The critical quenching current of the short sample taken out of the colored portion is degraded into 70% of that in the other uncolored portion, (3) No distortion of the metallic composition or no degradation of the critical quenching current is recognized in the uncolored portion of the winding.
These results suggest that the partial and steep temperature gradient was developed around the ruptured point along the superconducting winding after the quenching was induced.
