| 摘要 |
PURPOSE:To increase a short circuit current controlling effect, and to decrease a voltage drop in normal operation, by holding a high temperature superconductor, whose resistance is significantly large in normal conductive state compared with the resistance of a conductor as a main power line, at the temperature which is at least nearly a critical temperature. CONSTITUTION:A high temperature superconductor 1 which has very large resistance in normal conductive state is disposed within a cooling system 2 in which superconductive state can be holded, to form a current limiting resistor apparatus 3. And, the current limiting resistor apparatus 3 is installed at the needed position of a main power line, with being connected to the conductor 4 of the main power line. A perovskite type oxide superconductor containing rare earth elements is preferable in practical use as the oxide superconductor of a high temperature superconductor because the critical temperature thereof is high. The oxide superconductor which contains rare earth elements and has a perovskite structure is a defective perovskite type oxide superconductor or the like, such as system LnBa2Cu3O7-delta or the like, in which oxygen defects exist. To obtain such oxide superconductor of, for example, system Y-Ba-Cu-O, constitutive elements comprising 1mol Y, 2mol Ba and 3mol Cu, by mole ratio, are first sufficiently mixed. Then, a temporary firing and a powdering are performed in turn to obtain a desired configuration, firing being performed thereafter. Next, a heat treatment is performed in oxygen atmosphere or an annealing being performed up to about 300 deg.C, thereby superconductive characteristic can be enhanced. |
