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

摘要

We reveal obstacles related to the application of HTS cylinders in current limiting devices based on the superconducting-normal state transition. It is shown that, at the critical current density achieved presently in bulk materials, and especially in BSCCO-2212, the required 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 fault clearing and, hence, the inductive FCLs and current-limiting transformers employing BSCCO cylinders do not return to the normal operation in the time required. For the recovery even with a non-current pause in the circuit, cylinders are needed with a critical current density an order of magnitude higher than the existing one.