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

TL;DR

This paper investigates the thermal and operational challenges of using high-temperature superconductor (HTS) cylinders, especially BSCCO-2212, in fault current limiters, highlighting limitations due to current density and cooling times.

Contribution

It provides a mathematical model demonstrating that current HTS cylinders cannot be quickly cooled and recovered in fault conditions, revealing key obstacles for their practical application in FCLs.

Findings

HTS cylinders require several centimeters of wall thickness at current densities.

Current HTS cylinders cannot be cooled within admissible times after faults.

Higher critical current densities are needed for practical fault current limiting.

Abstract

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 achieves several centimeters. 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 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, the cylinders are needed with the critical current density by an order higher than the existed ones.