Thermal regimes of HTS cylinders operating in devices for fault current limitation

Abstract

We reveal obstacles related to the application of HTS cylinders in current limiting devicesbased on the superconducting–normal state transition. It is shown that, at the criticalcurrent density achieved presently in bulk materials, and especially in BSCCO-2212, therequired thickness of the cylinder wall in a full-scale inductive device is several centimetres.A simple mathematical model of the operation of an inductive fault current limiter (FCL)is used to show that such cylinders cannot be cooled in an admissible time after a faultclearing and, hence, the inductive FCLs and current-limiting transformers employingBSCCO cylinders do not return to the normal operation in the time required. Forthe recovery even with a non-current pause in the circuit, cylinders are neededwith a critical current density an order of magnitude higher than the existingone.