TESTS OF 100 KW HIGH-T-C SUPERCONDUCTING FAULT CURRENT LIMITER

An inductive superconducting fault current limiter has been built and tested. It mainly consists of a copper coil, a superconducting tube, and an iron core which are concentrically arranged. The device is essentially a transformer with the secondary winding being the tube. The tube has diameter of 20 cm, a height of 35 cm, and is made of Bi2212 ceramic, fabricated by partial melting. The ceramic has the voltage current characteristic V similar to I-alpha with alpha approximate to 5. The critical current density defined by the 1 mu V/cm criterion is about 1400 A/cm(2). Depending on the number of turns of the coil, the nominal current of the device was between 130 A and 250 A. In short circuit tests in a 480 V circuit, the prospective fault current of 8 kA was limited to about 5 times the nominal current. The test results are in good agreement with detailed simulations of both the normal operation (e.g. impedance, AC-losses) and the behaviour under fault conditions (i.e. evolution of the current).