Studies of YBCO Strip Lines under Voltage Pulses: Optimisation of the Design of Fault Current Limiters

TL;DR

This study investigates the behavior of YBCO superconducting strip lines under voltage pulses, proposing a novel design to optimize fault current limiters by distributing dissipative zones and enhancing propagation velocity.

Contribution

The paper introduces a new design for superconducting YBCO strip lines that improves fault current limiter performance by distributing dissipative zones and increasing propagation speed.

Findings

Distributed dissipative zones reduce local overheating.

Enhanced propagation velocity improves fault response.

Successful implementation on a 3kW fault current limiter.

Abstract

We present experimental results on the behaviour of a superconducting YBCO/Au meander of length L submitted to short circuit tests with constant voltage pulses. The meander, at the beginning of the short-circuit, is divided in two regions; one, with a length L1 proportional to the applied voltage, which first switches into a highly dissipative state (HDS) while the rest remains superconducting. Then the rest of the meander will progressively switch into the normal state due to the propagation of this HDS (few m/s) from both ends. The part L1 has to initially support a power density proportional to r.Jp^2 (r is the resistivity of the bilayer and Jp the peak current density). To avoid local excessive dissipation of power and over heating on one part of the wafer in the initial period, we have developed a novel design in order to distribute the dissipating section of the meander into many separated small dissipative zones. Furthermore the apparent propagation velocity of these dissipative zones is increased by the number of propagation fronts. We will show results obtained on 3kW (300V, 10A) FCL on a 2" wafer which confirm the benefits of this new design.