RECOVERY CHARACTERISTICS OF A YBCO HIGH-TEMPERATURE SUPERCONDUCTING CURRENT-LIMITING ELEMENT FOR USE IN LOW-VOLTAGE DISTRIBUTION-SYSTEMS

Recovery characteristics of a YB2Cu3O7-y high-temperature superconductor after its quenching are investigated experimentally in this paper. The zigzagshape superconducting elements 310 mm in effective length and 1.5 mm x 1 mm in cross section are examined. AC current injection tests are carried out. It is clarified that the high-temperature superconducting element has a quick transition characteristic between the super- and normal-conducting states. The test elements recover to zero impedance state from high impedance state just after removing the over-current when the magnitude of accumulated heats due to the over-current during the quenching period is less than 1 J. Furthermore, it is found from experiments that the critical current level might be reduced by some self-magnetization due to a high current during the quenching period.