Hazardous location compliant solid state circuit protection devices include safety lockout components ensuring disconnection as a safeguard in the completion of power system maintenance and service tasks by responsible personnel. The safety lockout components may include a mechanical lockout interfacing with a physical lock element, an electrical lockout implemented through the controls of the solid state circuit breaker device, and combinations thereof. Visual device feedback and confirmation may be provided to personnel that the lockouts have been successfully activated, as well as successfully deactivated to reconnect and restore operation of the load side circuitry.

The present disclosure relates to a shared transfer switching system with built in relay testing ability, for transferring power received by a load from a preferred AC power source to an alternate AC power source, or transferring power being received by the load from the alternate AC power source to the preferred AC power source. The system selectively controls various ones of the relays used to apply power from either the preferred or alternate power sources to the load, such that the relays are switched from open to closed states at controlled times, while voltage measurements are made at select locations between the relays. The system can identify which specific ones of a plurality of relays associated with each of the preferred and alternate power sources has properly opened and closed, and thus verify that all of the relays needed to switch between the preferred and alternate power sources are operating properly.

There is disclosed a circuit breaker arrangement for interrupting a current flowing through a direct current (DC) transmission line including a semiconductor switching device and a pulse injection circuit configured to inductively inject into the transmission line a pulse current that opposes the current flowing through the transmission line to thereby reduce the current in the transmission line to cause the semiconductor switching device to turn-off to interrupt the path for the current flow through the transmission line.

A low-voltage protective switching device includes: at least one outer conductor path from an outer conductor supply terminal of the low-voltage protective switching device to an outer conductor load terminal of the low-voltage protective switching device; a neutral conductor path from a neutral conductor terminal of the low-voltage protective switching device to a neutral conductor load terminal of the low-voltage protective switching device; a mechanical bypass switch disposed in the outer conductor path; a first semiconductor circuit arrangement of the low-voltage protective switching device connected parallel to the mechanical bypass switch; an electronic control unit; a current measuring arrangement disposed in the outer conductor path, the current measuring arrangement being connected with the electronic control unit; and a first mechanical disconnecting switch disposed in series to the first semiconductor circuit arrangement and in parallel to the mechanical bypass switch. The electronic control controls the mechanical bypass switch.

A circuit breaker includes: at least one external conductor section from an external conductor supply connection in the circuit breaker to an external conductor load connection in the circuit breaker; and a neutral conductor section from a neutral conductor connection in the circuit breaker to a neutral conductor connection in the circuit breaker. The at least one external conductor section includes a mechanical bypass switch and a first mechanical isolating switch which are serially arranged. A second mechanical isolating switch is arranged in the neutral conductor section. A semiconductor circuit arrangement in the circuit breaker is connected in parallel to the bypass switch. A current measuring device is arranged in the at least one external conductor section that is linked to an electronic control unit in the circuit breaker. The electronic control unit operates the bypass switch, the first and second mechanical isolating switches, and the semiconductor circuit arrangement.

A low-voltage circuit breaker includes: at least one external conductor section of an external conductor power terminal of the low-voltage circuit breaker connected to an external conductor load terminal of the low-voltage circuit breaker; and a neutral conductor section of a neutral conductor connection of the low-voltage circuit breaker connected to a neutral conductor load terminal of the low-voltage circuit breaker. A mechanical bypass switch is arranged in the at least one external conductor section. A semiconductor circuit arrangement of the low-voltage circuit breaker is switched parallel to the bypass switch. A first current measuring arrangement is arranged in the at least one external conductor section, which is connected to an electronic control unit of the low-voltage circuit breaker. The electronic control unit is configured to actuate the bypass switch and the semiconductor circuit arrangement when a prespecifiable overcurrent is detected by the current measuring arrangement.

Solid state and hybrid circuit protection devices include improved arc-less switching capability and overcurrent protection, improved terminal assemblies and improved thermal management features that reduce or eliminate ignition sources for hazardous environments. The solid state and hybrid circuit protection devices are ignition protected and avoid possible explosions and therefore obviate a need for conventional explosion-proof enclosures to ensure safe operation of an electrical power system in a hazardous location.

A circuit breaker includes: at least one external conductor section from an external conductor supply terminal of the circuit breaker to an external conductor load terminal of the circuit breaker; and one neutral conductor section from a neutral conductor terminal of the circuit breaker to a neutral conductor load terminal of the circuit breaker. A mechanical bypass switch is arranged in the at least one external conductor section. A semiconductor circuit arrangement of the circuit breaker, which semiconductor circuit arrangement comprises a four-quadrant switch, is connected in parallel with the bypass switch. A current measuring arrangement is arranged in the at least one external conductor section and is connected to an electronic control unit of the circuit breaker. The electronic control unit is configured to operate the bypass switch and the semiconductor circuit arrangement in a prespecifiable manner. A voltage-dependent resistor is arranged in parallel with the bypass 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.

An electric grid includes feed-ins, loads, and a distribution grid, which is arranged therebetween. The distribution grid comprises at least one busbar and at least one device for opening or closing a DC circuit. The at least one device includes an electric switch for opening or closing the DC circuit, a fault current detector, a trigger unit, a precharging device, and a control unit for automatically closing the electric switch after the precharging process. The electric switch opens the DC circuit via the trigger unit if a fault current is detected by the fault current detector, and the precharging device restores the voltage on the busbar prior to closing the electric switch.