Current cycling test on HTSC for Westinghouse current leads

Abstract

Absrrucz -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, (B=O) of 970 A/cm2 at 77 K and a total contact joint resistance for both terminals of 2 pR 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 80,000 cycles and 250,000 cycles, measurements of J, and contact joint resistance were repeated. No degradation in either J, or contact joint resistance was detected. The testing and the test results are discussed in detail.