Abstract: In a superconducting short circuit current limiter for an AC power supply net including an iron core, a primary coil and a secondary short-circuited superconductive coil, both being magnetically coupled with the iron core but being arranged at a distance from each other, the iron core has gaps at opposite sides of the secondary coil for thermically uncoupling the secondary coil from the rest of the magnetic core and a tertiary coil is arranged closely adjacent the primary coil in a magnetically strongly coupled relationship therewith, and has a heat capacity sufficient to accommodate the joulean heat generated when a fault or short circuit occurs in the power supply net, and the iron core has an area of reduced cross-section which is so selected that it becomes magnetic flux saturated when the current in the primary coil exceeds a predetermined reaction current level.