Provided is a directional overcurrent relay using a superconducting fault current limiter voltage as a relay element, and a method for correcting the same. The directional overcurrent relay using a superconducting fault current limiter voltage as a relay element includes: a current measuring circuit measuring a current of a line connected from a system power source to a load, a voltage measuring circuit measuring a voltage at both ends of a superconducting fault current limiter connected to the line, and a correcting circuit correcting a tripping time T.sub.trip by using a fault current I.sub.f that is the current of the line and a superconducting fault current limiter voltage V.sub.SFCL that is the voltage at both ends of the superconducting fault current limiter and the tripping time T.sub.trip is maintained consistently regardless of whether the superconducting fault current limiter operates or not.

The invention proposes a high-voltage direct current cut-off device, comprising: in series, a cut-off device and a current limiter; an accumulation line in parallel with the current limiter, an oscillating circuit, in parallel with the cut-off apparatus, comprising an oscillation control switch and having an inductance wherein the accumulation line includes at least two accumulation capacitors, and in that the oscillation line extends from a branch connection point of the accumulation line situated between the two accumulation capacitors, determining a secondary segment of the accumulation line connected to the main conduction line between the current limiter and the main cut-off apparatus so as to form part of the oscillating circuit.

An item of interconnection equipment for a high-voltage DC grid includes first and second terminals for connection to first and second lines of a high-voltage DC grid, a third terminal for connection to a local station or a line of the high-voltage grid, a node connected to the first to third terminals, a first superconductor current limiter and a first controlled switch connected in series between the first terminal and the node, a second superconductor current limiter and a second controlled switch connected in series between the second terminal and the node, a third superconductor current limiter and a third controlled switch connected in series between the third terminal and the node, and a current injector configured to inject an electrical current into the node.

A protection system capable of safely quenching a high temperature superconductor (HTS) magnet coil. The protection circuit provides for a frequency loss induced quench design that advances the protection technology for HTS magnet coils and provides a protection system that is capable of quickly distributing the heat energy uniformly in all the coil sections when a localized hot-spot is created.

A cryogenic fuse comprising a superconducting element arranged in a first chamber, the first chamber containing a cryogenic fluid, the cryogenic fuse being such that the superconducting element comprises a breaker initiation zone configured to determine a melting current and the first chamber is surrounded by a second chamber, placed under vacuum. The melting current or a melting time of the breakdown initiation zone may be adjusted.

A superconducting current limiter having at least one superconducting conductor (3) wound so as to form a coil (2) extending in a single plane and connecting a first electrical connection terminal to a second electrical connection terminal, an electrically insulating spacer (8) being arranged between two turns of the coil. The superconducting conductor (3) consists of at least two separate superconducting cables (5) wound in parallel and whose ends are electrically connected by the first electrical connection terminal and by the second electrical connection terminal, respectively. An electrically conductive spacer (12) is arranged between two of said separate superconducting cables (5), this electrically conductive spacer (12) being able to be traversed by a cooling fluid.

A current-breaking device for high-voltage direct current includes a main conduction-line and a secondary conduction-line connected in parallel between its terminals. The main conduction-line comprises a first controlled-switch and a circuit connected in series. The circuit comprises a first current-limiter and a first capacitor connected in parallel. The secondary conduction-line comprises a second controlled-switch. These conduction lines cooperate to form an oscillating circuit that oscillates with an amplitude that is at least equal to limiting current passing through the current limiter.

Embodiments of the disclosure include a fault current limiter (FCL) providing symmetrical electrostatic shielding. In some embodiments, a FCL includes a superconductor maintained at a first voltage greater than zero voltage, and an enclosure containing the superconductor, the enclosure maintained at a second voltage greater than zero voltage, wherein the second voltage is different from the first voltage. The FCL may include an electrical connection directly coupling the superconductor and the enclosure, wherein the electrical connection enables each of a plurality of current limiting modules of the superconductor to receive, during a fault condition, an equal or unequal sub-portion of a total voltage drop.

A superconducting fault current limiter (10) is shown. It comprises a cryostatic cooling system (20) for containing a cooling medium (26), a superconducting wire (30) immersed in the cooling medium (26) and configured to carry a current, the superconducting wire (30) becoming non-superconducting above a critical current density, and a plurality of heat dissipation elements spaced along and projecting from the superconducting wire (30), wherein the heat dissipation elements have an electrically insulating coating, and whereby the heat dissipation elements transfer heat from the superconducting wire (30) into the cooling medium (26).

A fault current limiter, including: an inductor, a direct current circuit breaker, a shunt resistor, and a first fixed resistor. The inductor includes wound superconducting wires. The direct current circuit breaker and the inductor are connected in series to form a series branch. The shunt resistor is connected in parallel to the series branch. The first fixed resistor is connected in parallel to the direct current circuit breaker.