Assessment of Small Bend Diameter Magnesium Diboride Wire for a Superconducting Fault Current Limiter Application

This paper reports results of tests on several MgB₂ round wire samples wound with small bend diameters. Wire suitability for use in a resistive type superconducting fault current limiter with a practical aspect ratio is assessed in terms of current limiting performance and tolerance to mechanical process handling. A fully controllable low current supply was used to determine the variation of the wire impedance against frequency and temperature. The frequency response enabled the calculation of coil inductance and superconducting resistance. Critical temperatures measured were in the range of 34 K-39 K. A high current supply was used to test the coil current limiting properties in the temperature range 25-32 K in self field at 50 Hz. Good, repeatable current limiting properties were observed with quench currents in the range 95-390 A. Good tolerance to mechanical process handling was also evident.