A current cut-off device for high-voltage DC current includes: between a primary point and an intermediate point, a primary diversion member and, in parallel, a primary surge protector; a secondary mechanical switch between the intermediate point and the secondary point; a main resonator whose terminal is linked to the secondary point; a main oscillation switch; a main surge protector, in parallel with a main capacitance of the main resonator; wherein the main oscillation switch includes three terminals linked respectively to the primary point, to the intermediate point and to the other terminal of the main resonator; the changeover switch can switch at least between three direct, inverting and isolated states.

A system includes a dry contact with a first pair of switchable electrodes, a wet contact with a second pair of switchable electrodes, an arc suppressor, and a controller circuit operatively coupled to the arc suppressor and the first and second pairs of switchable electrodes. The controller circuit is configured to detect a failure of the wet contact and determine a stick duration associated with the first pair of switchable electrodes. The stick duration is based on a duration between an instance when a coil of the dry contact is deactivated and an instance of separation of the first pair of switchable electrodes during deactivation of the coil. The controller circuit generates, in-situ and in real-time, health assessment for the first pair of switchable electrodes based on a comparison of the determined stick duration with an average stick duration associated with a window of observation.

Provided is an arc suppression device including one or more current-limiting circuits provided in parallel with a circuit breaker that switches between feeding and shutoff of power from a power supply. The current-limiting circuit shuts off a current from the power supply when the power from the power supply is fed to a load through a circuit breaker. The current from the power supply is shut off when a voltage generated by a potential difference between contacts of the circuit breaker becomes a predetermined voltage or higher in a case where feeding of the power from the power supply to the load is shut off by the circuit breaker. The potential difference is generated upon shutoff.

Provided are a method and apparatus for calculating fault resistance and a current-limiting current of a superconducting fault current limiter. The method includes: calculating a first short-circuit fault current I.sub.n(t) of a power grid short-circuit fault transient circuit; calling an external characteristic model U(I,t), and calculating resistance R.sub.n(t) of a superconducting fault current limiter under the first short-circuit fault current I.sub.n(t); adding the resistance R.sub.n(t) of the superconducting fault current limiter into the power grid short-circuit fault transient circuit, and calculating a second short-circuit fault current I.sub.m(t), where m=n+1; and determining whether an error between the second short-circuit fault current I.sub.m(t) and the first short-circuit fault current I.sub.n(t) is smaller than a preset threshold value, if yes, determining the fault resistance and the current-limiting current of the superconducting fault current limiter to be R.sub.n(t) and I.sub.m(t) respectively; otherwise, I.sub.n(t)=I.sub.m(t), returning for iteration.

A switching apparatus for conducting and interrupting electrical currents includes: a first mechanical contact arrangement; a semiconductor switch which is connected in parallel to the first mechanical contact arrangement; a second mechanical contact arrangement connected in series to the first mechanical contact arrangement; an auxiliary coil electrically isolated from a circuit of a switching drive used to move contacts of the first and second mechanical contact arrangements, and which is electromagnetically coupled to a coil of the switching drive such that a voltage is generated therein when a voltage supply of the switching drive is switched off; and a switching electronics for switching the semiconductor switch on and off, and which is supplied with the voltage generated in the auxiliary coil when the voltage supply of the switching drive is switched off. The switching electronics switches the semiconductor switch on and off multiple times according to a prespecified sequence.

Methods and systems for suppressing arc formation in branch breakers provide a load center that can monitor a branch breaker for indications of arc formation. The load center may include a main breaker that can immediately cut current to the upon receiving an indication of an arc forming in the branch breaker. The indication may be provided by a sensor circuit that sends a trigger signal to the main breaker when arc formation is detected within the branch breaker. The main breaker checks that the trigger signal indicates arc formation, then cuts current to suppress the arc. The main breaker then waits a short period for the branch breaker to clear before restoring current. The wait period is sufficiently short such that devices receiving power from the load center are not adversely affected. To improve cutoff and restoration response times, the main breaker employs a solid-state trip switch.

A current cut-off device for high-voltage DC current includes: between a primary point and an intermediate point, a primary diversion member and, in parallel, a primary surge protector; a secondary mechanical switch between the intermediate point and the secondary point; a main resonator whose terminal is linked to the secondary point; a main oscillation switch; a main surge protector, in parallel with a main capacitance of the main resonator; wherein the main oscillation switch includes three terminals linked respectively to the primary point, to the intermediate point and to the other terminal of the main resonator; the changeover switch can switch at least between three direct, inverting and isolated states.

A two terminal arc suppressor for protecting switch, relay or contactor contacts and the like comprises a two terminal module adapted to be attached in parallel with the contacts to be protected and including a circuit for deriving an operating voltage upon the transitioning of the switch, relay or contactor contacts from a closed to an open disposition, the power being rectified and the resulting DC signal used to trigger a power triac switch via an optoisolator circuit whereby arc suppression pulses are generated for short predetermined intervals only at a transition of the mechanical switch, relay or contactor contacts from an closed to an open transition and, again, at an open to a close transition during contact bounce conditions.

A hybrid circuit breaker includes: input connectors configured to receive electrical energy from a power grid; output connectors configured to transfer electrical energy to a load; current paths, each connecting a respective input connector, of the input connectors, and a respective output connector, of the output connectors; an electro-mechanical bypass switch in at least one of the current paths; a semiconductor circuit in parallel with the electro-mechanical bypass switch; a controller configured to control a commutation from the current path in which the electro-mechanical bypass switch is arranged to the semiconductor circuit in a switching operation; and an active cooling device in a vicinity of the electro-mechanical bypass switch. The active cooling device is adopted to cool movable parts of the electro-mechanical bypass switch.

An electromechanical switching protection system includes an electromechanical switchgear having contacts configured to selectively open and close in response to a control signal, and a junction field effect transistor (JFET) device electrically connected in series with the electromechanical switchgear between an input terminal and an output terminal of the electromechanical switching protection system, a gate of the JFET device being electrically connected to the output terminal.