Current cycling test on HTSC for Westinghouse current leads

To evaluate the reliability of high temperature superconducting current leads for repetitive current ramping operations such as in a magnetic separator, a ceramic high temperature superconductor with its copper terminals was subjected to current cycling tests in liquid nitrogen. The superconductor, a cylindrical rod of BSCCO-2212 fabricated by a melt cast process, has an initial J/sub c/ (B=O) of 970 A/cm/sup 2/ at 77 K and a total contact joint resistance for both terminals of 2 /spl mu//spl Omega/ in the current range of 100 to 500 A. Due to power supply limitation, the cycling current magnitude was set at 50 A. The cycling rate was 1 cycle per minute, 30 seconds on 30 seconds off. After approximately 80000 cycles and 250000 cycles, measurements of J/sub c/ and contact joint resistance were repeated. No degradation in either J/sub c/ or contact joint resistance was detected. The testing and the test results are discussed in detail.<>