CURRENT LIMITER

PURPOSE: To prevent an overcurrent from occurring when a single ground fault occurs by a method wherein a transformer whose three secondary windings are shorted is provided, a three-winding reactor is composed of coils connected in series to the three secondary windings of the transformer, and the secondary windings of the reactor are formed of superconductive conductor of the same critical current characteristics with the coils. CONSTITUTION: A transformer is composed of primary coils 4a to 4c and secondary coils 5a to 5c. The secondary coils 5a to 5c are connected to coils 6a to 6c in series respectively, and a three-winding reactor comprises the coils 6a to 6c. The secondary coils 5a and 5c and the coils 6a to 6c are formed of superconductive wire of the same critical current characteristics. In a normal state, no leakage reactance occurs in the coil 6a, but the three-winding reactor increases in zero-phase impedance when a single wire is grounded to induce a current limiting effect. When a system fault other than a single ground fault takes place, a large leakage reactance occurs in the primary coils 4a to 4c to induce a current limiting effect.