Magnetic circuit switching element with superconducting coil

In an existing power system, high-current circuit breakers are widely used. Meanwhile, we propose a new switching device using a switching of magnetic paths. It is a magnetic circuit switch activated by on/off of superconducting coils wound on iron core-legs. We have carried out an experiment using a small experimental device with two superconducting coils (control coils). When the control coil is shorted, the voltage of the output coil in the shorted side becomes 0 V because the magnetic flux is blocked completely by the induced shielding current of the superconducting coil. It was confirmed that the current of the superconducting coil is decided by the turn-ratio of the coils both experimentally and theoretically. Therefore, it was assured that any tremendous overcurrent does not flow in the shorted superconducting control coils. After this, we applied this device into a model of two-circuit transmission system and confirmed the fundamental behavior in case of a line fault. The experimental result shows that the fault current is suppressed almost perfectly and the transmission system can continue the power transmission without any intermission.