Study of Superconducting Fault Current Limiter Functionality in the Presence of Long-Duration Short Circuits

In this paper, superconducting fault current limiter (SFCL) operation in the presence of a long-duration fault is presented. The SFCL device utilizes second-generation high-temperature superconducting (2G HTS) tapes, which exhibit zero resistance under normal operating conditions. When the current exceeds the critical threshold specific to the superconducting tape, then it undergoes a transition to a resistive state—a phenomenon known as quenching. As a consequence, this leads to introducing impedance into the circuit, effectively limiting the magnitude of the fault current. Additionally, this transition dissipates electrical energy as heat within the material. The generated energy corresponds to the product of the voltage drop across the quenched region and the current flowing through it during the fault duration. In specific configurations of the power system, it is expected that the SFCL should limit the fault current for an extended period of time. In such a situation, a certain amount of energy will be generated, and it must be verified that the tape loses its properties or parameters (e.g., lowering the critical current value) or is destroyed. Therefore, experimental tests of the tapes were conducted for various short-circuit current, voltage drop, and short-circuit duration values to assess the effect of the amount of generated energy on the 2G HTS tape. Additionally, recommendations are presented on how to protect the SFCL during long-lasting short circuits.