Abstract: The present invention includes a first switch 4a, a second switch 4b and a capacitor 4d. The first switch 4a normally in a closed state is connected in series between a power source 1 and load, and opens when an accident builds up. The second switch 4b normally in an open state closes almost simultaneously with the opening of the first switch 4a. The capacity 4d normally charged by an arbitrary voltage has predetermined electrically capacity. The serial connected circuit consists of the second switch 4b and capacitor 4d, it is connected in parallel to the first switch 4a.

Abstract: A current limiter having a plurality of current limiting units provided for electric paths constituting a plurality of phases. Each current limiting unit is constituted by a superconducting coil functioning as a first current limiting element formed in a non-inductive winding manner by connecting two superconducting coils in series, which superconducting coils are wound in opposite directions and equal in size and number of turns, and a superconducting coil functioning as a second current limiting element connected in parallel to the first current limiting element and having a predetermined impedance value. These current limiting units are contained within a cryostat and separated by a magnetic shield member for electromagnetically isolating the respective phases.

Abstract: A superconducting current limiting device for limiting overcurrent flowing in a load. The device includes a current limiter with a first superconducting coil, a second superconducting coil arranged coaxially with the first superconducting coil so as to have a negative magnetic coupling condition, and a third superconducting coil arranged coaxially with the first and second superconducting coils so as to have a negative magnetic coupling condition with the second superconducting coil and so as to have a positive magnetic coupling condition with the first superconducting coil. The first and second superconducting coils are electrically connected in series. The device includes a high speed switch connected electrically in series with the third superconducting coil to form a series circuit. The series circuit is electrically connected in parallel with the second superconducting coil.

Abstract: An improvement of a current limiting device using a superconductive coil. A trigger coil and current limiting coils are formed as a superconductive coil. A switching element which is actuated when a current limiting operation by the current limiting coil occurs, is connected in series to the trigger coil to immediately suppress heat generation by the trigger coil. When a quenching is detected by a detector, the trigger coil is disconnected and an additionally provided recovery coil is connected to speed up the recovery operation. A plurality of trigger coils connected in series may be used.

Abstract: In a superconducting AC (alternating current) current limiter, quenched trigger coil assembly is quickly recovered to the superconductive state by minimizing a loop current flowing through the trigger coil assembly.

Abstract: There is disclosed a superconducting switch including two superconducting coils wound on a common bobbin wherein these coils have the same critical current value, and are connected in parallel so that magnetomotive forces which are the same in magnitude and opposite to each other in direction are produced. This superconducting switch is non-inductive and responds to an overcurrent to securely operated at a high speed. There is also disclosed a current limiter including a current limiting coil connected in parallel with the superconducting switch used as a trigger coil. The superconducting switch exists within a magnetic field produced by the current limiting coil. There is further disclosed a current limiter such that the current limiting coil is constructed to be of non-inductive type using two coils, and a superconducting switch is connected to either of these coils.