Quench behavior of high temperature superconductor (RE)Ba₂Cu₃O_x CORC cable

High temperature superconductor (HTS) (RE)Ba2Cu3Ox (REBCO) conductor on round core cable (CORC) shows great advantages on high current capacity and power density. In REBCO CORC cables, current is redistributed among tapes through terminal contact resistances (TCR) when a local quench occurs. Therefore, its quench behaviour is different from single tape situation. To better understand the underlying physical process of local quenches in CORC cables, a new 3D multi-physics modelling tool for CORC cables is developed and presented in this paper. In this model, the REBCO tape is treated as a thin shell without thickness, and four models are coupled: T-formulation model, A-formulation model, a heat transfer model and an equivalent circuit model. The T-formulation is applied to the conductor shell only to calculate current distribution, which will be input into A-formulation model; the A-formulation is applied to the whole 3D domain to calculate magnetic field, which is then fed back to the T-formulation model. The hot spot induced quenches of CORC cables are analysed. The results show that the thermal stability of CORC cable can be considerably improved by reducing TCR. The minimum quench energy (MQE) increases rapidly with the reduction of TCR when the resistance is in a middle range, which is about 5 μΩ ≤ R_t ≤ 200 μΩ in this study. When TCR is too low (R_t < 50 μΩ) or too high (R_t > 50 μΩ), the MQE shows no obvious variation with TRC. With low TCR, a hot spot in one tape may induce an over-current quench on other tapes. This will not happen in a cable with high TCR. In this case, the tape with hot spot will quench and burn out before inducing a quench on other tapes. The modelling tool developed can be used to design CORC cables with improved thermal stability.