Thermal Stability Analysis of YBCO Tapes Under DC Overcurrent

High-temperature superconducting (HTS) cable has the merits of high capacity and small volume in the normal operation condition. However, the fault current, which could be 10–30 times of the nominal current, gives a great challenge to its thermal stability. Due to the overcurrent, the HTS tapes will quench to resistive state and result in generating large amount of heat, which may degrade or even damage the HTS tapes. Therefore, it is of great significance to study the thermal stability of superconducting tapes. This article studies the thermal characteristics of different HTS tapes under dc overcurrent. The testing tapes are made of YBCO produced by Shanghai Superconductor (SHSC) and Samri advanced material (SAM). The thermal stability is defined as the maximum overcurrent and impact duration that a tape can withstand before getting its properties degraded. According to the testing results, the thermal stability of the HTS tape with copper reinforced layer is better than brass and stainless steel. The thicker the thickness of the tape, the better the stability. But the thermal stability of 25
$\mu \text{m}$
copper reinforced YBCO is close to 50
$\mu \text{m}$
. Owing to the resistivity and specific heat capacity, with the same pulse lengths, the 150
$\mu \text{m}$
copper reinforced YBCO can be pulsed to twice the current of 25
$\mu \text{m}$
.