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.

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.

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 method for switching an operating current in a meshed DC voltage network enables operating currents in a DC voltage network to be switched economically in both directions. At least one converter connected to the DC voltage network is controlled in such a way that a zero current is generated in a switching branch having a mechanical switch and the mechanical switch is actuated in accordance with the generated zero current.

A control system includes a control device adapted to be connected to a live line and a neutral line that transmit a grid power, and to a load via a first power line and a second power line. The control device includes: a first switch adapted to be connected between the live line and the first power line; a second switch adapted to be connected between the neutral line and the second power line; a coupler adapted to be connected to the first power line, receiving a communication signal, and coupling the communication signal to the first power line; and a controller controlling the first and second switches to synchronously alternate between an ON state and an OFF state, and outputting the communication signal to the coupler when the first and second switches operate in the OFF state.

A method for synchronizing opening of a circuit breaker is presented. The circuit breaker is arranged to interrupt a current to an inductive load. The method is performed in a control device (2) and comprises measuring (S100) a reference signal as a function of time for a circuit breaker (1) connected to an inductive load (5), obtaining (S110) an indication of a power factor of the inductive load through the circuit breaker, determining (S120) an arcing time for opening of the circuit breaker, the arcing time being dependent on the obtained indication of a power factor, predicting (S130) a zero crossing of a current through the circuit breaker based on the measured reference signal, and providing (S140) contact separation of a contact pair of the circuit breaker at a point of time before the predicted zero crossing, the point of time being determined by the determined arcing time and the predicted zero crossing. A control device, a circuit breaker arrangement, and a computer program for synchronizing opening of a circuit breaker are also presented.

A commutating circuit breaker that works by progressively inserting increasing resistance into a circuit. This is done via physical motion of a shuttle that is linked into the circuit by at least one set of sliding electrical contacts on the shuttle (“shuttle electrodes”) that connect the power through the moving shuttle to a sequence of different resistive paths with increasing resistance; the motion of the shuttle can be either linear or rotary. A feature of the commutating circuit breaker is that at no point are the shuttle electrodes separated from the matching stationary stator electrodes so as to generate a powerful arc, which minimizes damage to the electrodes. Instead, the current is commutated from one resistive path to the next with small enough changes in resistance at each step that arcing can be suppressed. The variable resistance can either be within the moving shuttle, or the shuttle can comprise a commutating shuttle that moves the current over a series of stationary resistors. In either case, a “soft” opening of the circuit can be accomplished, with low switching transients, provided that the maximum step change of resistance is limited until the current is nearly extinguished. Commutating circuit breakers work equally well for DC or AC power.

The disclosure relates to an arrangement and a method for switching an open contact gap by a switching device, wherein a galvanically isolated energy transmission of high-frequency energy provides an actuator energy for at least one switching device, in particular a vacuum interrupter. For the purpose of energy transmission, the switching device is connected to the high-frequency source via a dielectric resonator, the switching device being designed such as to be configured for converting the transmitted energy into actuator energy.

The disclosure relates to an arrangement and a method for switching an open contact gap by a switching device, wherein a galvanically isolated energy transmission of high-frequency energy provides an actuator energy for at least one switching device, in particular a vacuum interrupter. For the purpose of energy transmission, the switching device is connected to the high-frequency source via a dielectric resonator, the switching device being designed such as to be configured for converting the transmitted energy into actuator energy.