Within a direct current hybrid circuit breaker (DC HCB), a capacitance is provided in a semiconductor switch path in series with a semiconductor switch and the semiconductor switch is in parallel with a surge arrestor to facilitate opening the DC HCB. The semiconductor switch path is connected in parallel with a mechanical switch path that includes a mechanical switch. The circuit causes the current through the mechanical switch to ramp down while the current through the semiconductor switch ramps up to a supply current. The mechanical switch can open without current and against no recovery voltage.

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.

Various embodiments of the teachings herein include a switching device for a DC voltage grid. The device may include: a first controllable semiconductor switch with a control contact and two load contacts; and a controller for the first switch using a control signal at the control contact. The controller is configured to: actuate the first switch using a control pulse that causes the electrical conductivity of the semiconductor switch to reduce for less than 1 ms; apply a current to a test circuit including the first switch; ascertain a first value representing the voltage or the change in voltage across the first switch as a result of the control pulse and the applied current; analyzing the first value; and generating a signal that represents the functionality of the first semiconductor switch.

The invention relates to a method and a device for cutting off electric current. The device comprises at least one fixed contact and at least one moving contact that can move between a closed position and an open position, and at least one permanent magnet mounted together with the moving contact, such that the permanent magnet and the moving contact are able to move at the same time. The magnetic field of the magnet interferes with the area where the arc occurs and moves with the moving contact along its path, so with a small number of magnets, arc quenching capacity increases. The method of the invention comprises moving a permanent magnet through the area where an electrical arc occurs between a moving contact and a fixed contact, such that the generated magnetic field runs through at least part of the area where the arc occurs.

A hybrid switch assembly for a circuit breaker assembly is provided. The circuit breaker assembly includes a housing assembly and an operating mechanism. The housing assembly defines a power electronic switch assembly cavity. A hybrid switch assembly includes a number of conductor assemblies, each conductor assembly including a movable conductor, and a stationary conductor. Further, each movable conductor is structured to move between an open, first position, wherein each movable conductor is spaced from and not in electrical communication with an associated stationary conductor, and a closed, second position, wherein each movable conductor is coupled to and in electrical communication with an associated stationary conductor. A number of the conductor assemblies further include a power electronic switch assembly. Each power electronic switch assembly includes an isolation contact assembly. Each isolation contact assembly is selectively coupled to, and in electronic communication with, the stationary conductor and the movable conductor.

Provided is a high voltage DC circuit breaker that interrupts a fault current flowing through a high voltage DC transmission line with a vacuum circuit breaker and a gas circuit breaker connected in series. The circuit breaker includes: a vacuum circuit breaker installed on a DC transmission line and operating to interrupt a current in the DC transmission line when a fault occurs on either side of the DC transmission line; a gas circuit breaker connected in series with the vacuum interrupter; an LC circuit connected in parallel with the vacuum circuit breaker and including a capacitor and a reactor connected in series to induce LC resonance; a first bidirectional switching device connected in series with the LC circuit and switching a current flowing in any of two opposite directions; and a second bidirectional switching device connected in parallel with the LC circuit.

Disclosed herein are methods and systems for causing a zero-current crossing in an electrical circuit. The circuit can be a DC circuit in which case a switch is caused to open at or nearly at the zero crossing. Alternatively, the circuit can be an AC circuit.

A device for switching a direct current in a pole of a direct current network includes two connecting terminals to be connected in series with the pole, an operating current path extending between the connecting terminals, at least one mechanical switch in the operating current path, a disconnection branch including a power switching unit for shutting down high short-circuit currents having power semiconductor switches that can be switched on and off, and a commutation device for commutating a current from the operating current path to the disconnection branch. In order to provide such a device which is economical, generates fewer losses and at the same time is able to switch high short-circuit currents quickly, the commutation device is provided with at least one inductive component.

A momentary circuit interrupter in series connection with a mechanical switch to provide protection against short circuit faults in a DC power circuit. The momentary circuit interrupter injects a transient voltage pulse via a pulse transformer to reduce a DC fault current to near zero in a DC circuit branch, thus allowing the mechanical switch to disconnect the faulty branch under a near zero-current condition. The power electronic circuit on the primary side of the transformer controls the discharge of a plurality of pre-charged capacitors to generate the transient voltage pulse during the fault interruption process, but otherwise does not incur any power loss during normal operation. The secondary winding of the pulse transformer conducts the main DC current, and is highly conductive to minimize the conduction power loss. The invention provides ultrafast response to a short circuit fault (even faster than solid-state circuit breakers and much faster than hybrid circuit breakers), significantly reduced overcurrent stress in the power system, and/or ultralow conduction power losses.

A direct current (DC) hybrid circuit breaker (HCB) includes a current sensor and a variable inductor. In the event of a short circuit fault current reaches a preset threshold, the current sensor will send a tripping signal to a controller, and the controller will command the gate drivers to conduct all the switches in the semiconductor switch path. This action will allow the fault current to be commuted to the power stack. When the current in a fast mechanical switch branch drops to near zero, the variable inductor will be driven out of the saturation and the secondary winding will send out a “safe-to-open” signal to the controller. After receiving the “safe-to-open” signal, the controller will initiate the turn off sequence of the fast mechanical switch path