The superconducting current limiter, a device without classical equivalent, appears to be one of the most promising and innovative applied superconducting devices for electric power systems. Its operation is based on the ultra-fast and natural transition of a superconducting coil when the current oversteps a predetermined threshold value. The authors propose a hybrid device consisting of a resistive series transformer and superconducting coils. The superconducting coils trigger the limitation. The latter is ensured by the primary self inductance of the transformer. This design allows the reduction of the current through the superconducting cable, the volume of superconductor and the cryogenic losses under normal operation. These advantages are brought about by a transformer whose magnetic coupling between the windings changes accordingly to the mode of operation. To study this device experimentally, a 150 V-50 A model has been developed. This model has been exposed to a number of tests under normal and fault operations. The results have demonstrated the satisfactory performance of this hybrid device, at least at a reduced scale. With a view to an industrial device, a 63 kV-1250 A system has been theoretically designed.
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