DC and AC Characteristics of Copper Clamp-Type Mechanical Joints of YBCO-Coated Conductors

CG Global R&D is currently working on the design and validation of resistive-type superconducting fault current limiters using second-generation-YBa2Cu3O7 coated conductors (YBCO CC). Noninductive modules are made using several series-connected YBCO tapes to accommodate the required design length. Copper clamp-type mechanical bridge joints are employed between these YBCO tapes. These joints are made by sandwiching two parallel tapes between copper plates. This type of configuration gives additional ruggedness to the joint compared to soldered superconducting bridge joints with the superconducting bridging element. The dc and ac resistive characteristics of these joints are studied as a function of the operating current. The ac losses in the YBCO tape are also measured as a function of applied current with line frequency of ~50 Hz.