Mechanism of Recovery Performance Improvement With Porous-Stabilized REBCO Tape for Resistive-Type Superconducting Fault Current Limiters

Resistive-type superconducting fault current limiters (R-SFCLs) utilizing rare-earth barium copper oxide (REBCO) tapes have been developed to limit fault currents. To balance recovery and current-limiting performances, a porous-stabilized REBCO tape was proposed. The experimental results showed that using a porous stabilizer with the REBCO tape and insulating epoxy reduced recovery time to 25%. However, the underlying mechanisms of this improvement in recovery performance are not yet clear. The aim of the present study is to understand these mechanisms. To do so, a vapor-film-collapse model was proposed to clarify the impact of the insulating epoxy on vapor film collapse. This model suggests that when liquid nitrogen (LN
₂
) comes into contact with the insulating epoxy, it causes a rapid decrease in the temperature of the insulating epoxy surface, leading to the collapse of the vapor film. Additionally, a liquid-retention model was proposed to investigate the effect of the porous stabilizer. This model indicates that if the porous stabilizer can retain LN
₂
, the equivalent heat flux observed in experiments can be achieved through evaporation of the retained LN
₂
.