Testing of the world's largest Bi-2223 high temperature superconducting coil

Three large high temperature superconducting coils were used in the 15 kV class fault current limiter (FCL), designed and fabricated as part of a Phase II US DoE Superconductivity Partnership Program. Each of these solenoids measures 1.0 m in diameter and 0.75 m long. Each coil is designed to carry 2000 Adc and withstand an AC ripple of 16 A at 120 Hz. Each coil is wound from 15 km of Bi-2223 silver tapes and has an inductance of 4 mH. These coils were co-designed by General Atomics (GA) and Intermagnetics General Corporation (IGC) and constructed at the latter. GA provided the cryogenics and auxiliary components for the overall cryomagnetic assembly. Each coil is cooled by three cryocoolers and the designed operating temperature is 35 K. This paper presents the design specification of these coils. A brief description of the cryogenic and auxiliary setup is given and results from the thermal and electrical testing, that took place at General Atomics from April 13 to May 20, 1999, are presented.