PERFORMANCE CHARACTERIZATIONS OF BI-2223 COMPOSITE POWDER-IN-TUBE CONDUCTOR ELEMENTS

A 30 MW superconducting magnetic energy storage (SMES) system for elec tric utility application is currently under design by Babcock & Wilcox . High-temperature-superconductor (HTS) current leads have been design ed to reduce the refrigeration load of the SMES system's 16 kA capacit y electrical connection between the 300 K power conditioning system an d the 4 K low-temperature-superconductor energy storage magnet. Each l ead employs an array of 18 parallel HTS conductor elements. Each condu ctor element consists of a sintered stack of Bi-2223 HTS powder-in-tub e tapes, each having an Au-alloyed Ag sheath. Laboratory performance c haracterization of preproduction conductor elements included critical current with applied field at 77 and 60 K, thermal and electrical cycl ing effects, critical current vs axial strain, and end-connection elec trical resistivity. Details of the conductor element application and c onstruction are described. The methodology and results of the performa nce characterization are presented. The testing demonstrates mechanica l robustness and electrical stability required for long-term practical application in the SMES system.