A direct-current circuit breaker includes a circuit breaker unit and a circuit unit that generates an oscillating current. The circuit unit includes a capacitor and a reactor, a high-speed closer, and a lightning arrester. The circuit breaker unit and the high-speed closer are aligned in a first direction with a distance therebetween that is equal to or longer than a certain spatial distance. The capacitor and the lightning arrester are aligned in a second direction intersecting the first direction with a distance therebetween that is equal to or longer than the spatial distance. A combination of the circuit breaker unit with the high-speed closer and a combination of the capacitor with the lightning arrester are aligned in a third direction intersecting the first direction and the second direction with a distance therebetween that is equal to or longer than the spatial distance.

A switching apparatus comprises: a first current-conductive branch (12) including a first switching element (24), the first switching element (24) configured to be switchable to selectively permit and block a flow of current in the first current-conductive branch (12); a second current-conductive branch (14) including a second switching element (32), the second switching element (32) configured to be switchable to selectively permit and block a flow of current in the second current-conductive branch (14); and first and second terminals (18,20) for connection, in use, to an electrical network (22), wherein the first and second current-conductive branches (12,14) extend between the first and second terminals (18,20), wherein the first current-conductive branch (12) further includes an energy storage element electrically coupled to the second switching element (32) so that the energy storage element is configured as a power source for enabling the operation of the second switching element (32), and the first switching element (24) is configured to be switchable to selectively direct a current flowing in the first current-conductive branch (12) to flow through the energy storage element so as to store energy in the energy storage element.

A circuit breaker and method of operation. The circuit breaker includes a first current path including a mechanical switch, such as an ultrafast mechanical switch, and a second current path in parallel connection to the first current path, and including a current injector, such as a transient commutation current injection circuit, in series with bidirectional power electronic switch. A short circuit fault current from a mechanical switch path is communicated to the electronic path via a current injection, followed by interrupting the fault current. A pulse current is generated to the electronic switch in the second current path, and the mechanical switch is opened during the pulse current. The pulse current and the electronic switch reduce or eliminate arcing upon the opening the mechanical switch.

A circuit breaker includes a solid-state switch, a sense resistor, a current detection circuit, and a switch control circuit. The solid-state switch and sense resistor are connected in series in an electrical path between a line input terminal and a load output terminal of the circuit breaker. The current detection circuit is configured to (i) sample a sense voltage that is generated across the sense resistor in response to load current flowing through the sense resistor, (ii) detect an over-current fault condition based on the sampled sense voltage, and (iii) output a fault detection signal in response to detecting the over-current fault condition. The switch control circuit is configured to control the solid-state switch, wherein the switch control circuit is configured to switch off the solid-state switch in response to the fault detection signal output from the current detection circuit.

A low-voltage circuit breaker device includes: at least one line conductor path from a line conductor supply connection of the low-voltage circuit breaker device to a line conductor load connection of the low-voltage circuit breaker device; a neutral conductor path from a neutral conductor connection of the low-voltage circuit breaker device to a neutral conductor load connection of the low-voltage circuit breaker device; a mechanical bypass switch arranged in the line conductor path; a first semiconductor circuit assembly of the low-voltage circuit breaker device being connected in parallel with the mechanical bypass switch; an electronic control unit for actuating the mechanical bypass switch and the first semiconductor circuit assembly; an ammeter assembly arranged in the line conductor path, which ammeter assembly is connected to the electronic control unit; and a second semiconductor circuit assembly arranged in the line conductor path.

Compliant electrical circuit protection devices are described for use in hazardous environments without presenting ignition risks for potentially explosive environmental conditions. Sensing features and systems may evaluate wiring limits and user selected settings for compatibility, detect loose connections and operating parameters to ensure safe operation of the device, and to intelligently diagnose and manage issues of concern for the circuit protection devices as well as the larger electrical power system.

Various examples are provided related to direct current circuit breakers and their control methods. In one example, among others, a hybrid direct current circuit breaker (DCCB) includes an ultrafast mechanical switch (UFMS) connected in series with a commutating switch (CS) or auxiliary circuit breaker (ACB); a main breaker (MB) including a series of η semiconductor switching stages in parallel with the UFMS and CS or ACB; and control circuitry that can turn off individual switching stages in a defined order in response to opening contacts of the UFMS. The switching stages can be turned off based upon a dielectric strength across the contacts as they open. In another example, a method includes opening contacts of an UFMS connected in series with a CS or ACB; and turning off individual switching stages of a series of η semiconductor switching stages connected across the UFMS and the CS or ACB.

A system including an arc flash sensor that detects an arc flash event and an arc flash mitigation device in communication with the sensor. The mitigation device includes a path of least resistance having a path input and a path output. The arc flash sensor is located downstream the output. The mitigation device includes an electro-mechanical switch between the input and the output and an actuator. The mitigation device also includes a bypass power switch device that includes a solid-state circuit interrupter and that conduct current between the input and the output in response to an open-circuit condition of the switch. A system controller is provided to generate a trigger to activate the actuator to generate the open-circuit condition of the switch, which causes the power switch device to interrupt a fault current associated with a fault event in response to detection of the arc flash event.

A high speed arc suppressor and method include a first phase-specific arc suppressor configured to suppress arcing across contacts of the power contactor in a positive domain and a second phase-specific arc suppressor configured to suppress arcing across the contacts in a negative domain. First and second high speed switches are configured to enable and disable operation of an associated one of the first and second phase-specific arc suppressors. First and second drivers are configured to drive the first and second high speed switches.

A method of operating a Fault Current Limiter Circuit Breaker including a plurality of FLCB modules connected in series, including at least a first module and a second module. Each module has a plurality of parallel component legs including a mechanical switch leg having a mechanical switch, a semiconductor switch leg having a semiconductor switch, and a Metal Oxide Varistor leg having a MOV. The method includes, when the FLCB is in an open configuration, obtaining an indication that the FLCB should be closed; in response to the obtained indication, closing the semiconductor switch of each of the modules; and, after the closing of the semiconductor switches and while the mechanical switch of the second module remains open, closing the mechanical switch of the first module.