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.

Systems and methods for providing information about thermal overload conditions and near-miss tripping events in a circuit interrupter are disclosed. The systems and methods provide a user with detailed information about thermal overload and near-miss tripping events, including how much time remains until a trip will be initiated due to a thermal overload, and what the real-time thermal capacity of the circuit interrupter is after a thermal overload condition ends.

A circuit breaker distribution system is configured to provide selective coordination. The system comprises a solid-state switch disposed as a main or upstream breaker and a switch with an over current protection disposed as a branch or downstream breaker. The solid-state switch comprises a microcontroller including a processor and a memory, and computer-readable logic code stored in the memory which, when executed by the processor, causes the microcontroller to: allow repeated pulses of current through to the branch or downstream breaker in an event of an overload or short circuit, and choose a maximum current limit for the solid-state switch as a “chop level” such that the chop level is chosen higher than a rated current of the solid-state circuit breaker but low enough that the solid-state switch is not damaged from repeated pulses over a period of time needed to switch OFF the branch or downstream breaker.

A circuit breaker distribution system is configured to provide selective coordination. The system comprises a solid-state switch disposed as a main or upstream breaker and a switch with an over current protection disposed as a branch or downstream breaker. The microcontroller to: allow repeated pulses of current through to the branch or downstream breaker in an event of an overload or short circuit, choose a maximum current limit for the solid-state switch as a “chop level” such that the chop level is chosen higher than a rated current of the solid-state circuit breaker but low enough that the solid-state switch is not damaged from repeated pulses over a period of time needed to switch OFF the branch or downstream breaker and add a pulse interval after the current chops to zero but before the solid-state circuit breaker returns to an ON state for a next pulse to begin.

An apparatus comprises a switch, a current monitor, and a controller. During operation, the switch controls an amount of current through the load. The current monitor samples a magnitude of the current through the load, a magnitude of which varies over time during a time duration. Based on integrating the sample magnitudes of the current through the load over the time duration, the current monitor produces a current sense value. The current sense value is representative of an amount of current through the load. The controller controls an operational state of the switch based upon a comparison of the current sense value with respect to an over-current threshold value. For example, in response to detecting a condition in which the current sense value is greater than the overcurrent threshold value, the controller turns OFF (deactivates) the switch, reducing or eliminating delivery of current through the load.

An embodiment electronic circuit includes an electronic switch comprising a load path, and a control circuit configured to drive the electronic switch. The control circuit is configured to operate in one of at least two operation modes. The at least two operation modes comprise a first operation mode and a second operation mode. The control circuit, in the second operation mode, is configured to perform a set of basic functions and, in the first operation mode, is configured to perform the set of basic functions and at least one additional function. The at least one additional function comprises generating a first protection signal based on a current-time-characteristic of a load current of the electronic switch and driving the electronic switch based on the first protection signal.

A power cutoff device includes a relay unit including a switch having a connecting state to be electrically conductive and a cutoff state to be electrically non-conductive, a cutoff unit connected in series to the switch, a current detector configured to detect an object current flowing through the cutoff unit, and a controller configured to control the relay unit and the cutoff unit. The cutoff unit has a connecting state to be electrically conductive and an irreversible cutoff state to be electrically conductive. The controller is configured to obtain a changing rate of the object current with respect to time. The controller is configured to cause the switch to be in the connecting state and cause the cutoff unit to be in the connecting state if determining that the changing rate is not greater than a changing-rate threshold. The controller is configured to cause the relay unit to be in the cutoff state and cause the cutoff unit to be in the irreversible cutoff state if determining that the changing rate is greater than the changing-rate threshold. This power cutoff device has a small size.

The invention discloses an adaptive fault clearing scheme for an MMC VSC-HVDC grid based on source-grid coordination. A grid-side circuit breaker topology is disposed at each end of each DC line of the MMC VSC-HVDC grid to coordinate with a source-side control strategy when a fault occurs to the DC line so as to isolate the fault together. When a system runs stably, the voltage regulation controller does not actuate, after the fault occurs, the voltage regulation controller is started, and the output voltage regulation coefficient decreases, so that voltage at outlets of the converters drops accordingly, and coordinates with voltage of the pre-charging capacitor of the grid-side circuit breaker topology to realize fault isolation based on source-grid coordination. The adaptive fault clearing scheme provided by the invention greatly improves the speed of fault isolation.

An integrated circuit that may be employed as a smart switch is described herein. In accordance with one embodiment the integrated circuit includes a power transistor coupled between a supply pin and an output pin and a current sensing circuit coupled to the power transistor and configured to generate a current sense signal indicative of a load current passing through the power transistor. The integrated circuit further comprises a monitor circuit configured to receive the current sense signal and to provide a protection signal based on the current sense signal and a threshold value, wherein the monitor circuit includes a filter that is configured to receive a filter input signal that depends on the current sense signal. The filter has a transfer characteristic with two or more time constants.

The invention discloses an adaptive fault clearing scheme for an MMC VSC-HVDC grid based on source-grid coordination. A grid-side circuit breaker topology is disposed at each end of each DC line of the MMC VSC-HVDC grid to coordinate with a source-side control strategy when a fault occurs to the DC line so as to isolate the fault together. When a system runs stably, the voltage regulation controller does not actuate, after the fault occurs, the voltage regulation controller is started, and the output voltage regulation coefficient decreases, so that voltage at outlets of the converters drops accordingly, and coordinates with voltage of the pre-charging capacitor of the grid-side circuit breaker topology to realize fault isolation based on source-grid coordination. The adaptive fault clearing scheme provided by the invention greatly improves the speed of fault isolation.