Thermal Instability and Current-Voltage Scaling in Superconducting Fault Current Limiters

TL;DR

This paper presents a 3D computer model for superconducting fault current limiters, analyzing how cooling, thickness, and properties affect stability, recovery, and voltage-current relationships.

Contribution

It introduces a comprehensive 3D simulation tool that incorporates variable properties and cooling conditions to study stability and scaling in superconducting limiters.

Findings

Cryogen boil-off parameters critically influence stability.

Recovery time increases with superconductor thickness.

Maximum voltage and current are exponentially related.

Abstract

We have developed a computer model for the simulation of resistive superconducting fault current limiters in three dimensions. The program calculates the electromagnetic and thermal response of a superconductor to a time-dependent overload voltage, with different possible cooling conditions for the surfaces, and locally variable superconducting and thermal properties. We find that the cryogen boil-off parameters critically influence the stability of a limiter. The recovery time after a fault increases strongly with thickness. Above a critical thickness, the temperature is unstable even for a small applied AC voltage. The maximum voltage and maximum current during a short fault are correlated by a simple exponential law.