An electrical power network employing fault location, isolation and system restoration. The system includes a plurality of switching devices electrically coupled along a power line downstream of a fault interrupting device. The switching devices each have current and voltage sensing capability and the capability to provide pulse tests for detecting fault presence. The fault interrupting device performs reclosing operations, and when the plurality of switching devices detect fault presence a predetermined number of times in coordination with reclosing operations performed by the fault interrupting device and detect loss of voltage, each switching device opens. The fault interrupting device closes when the switching devices open, and the switching devices sequentially pulse test and close from a furthest upstream switching device when detecting return of voltage and no fault presence until a switching device closest to the fault pulse tests and detects fault presence and locks open.

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 fault isolating device for use in a microgrid disconnected from a main power grid includes a voltage meter for detecting a voltage anomaly indicative of an electrical fault, a timer for establishing a time window that begins and ends a predetermined time after a voltage anomaly is detected, a switch that is opened at the start of the time window, and a microcontroller that determines whether to leave the switch open to isolate a faulted portion of the microgrid or to close the switch. A plurality of fault isolating devices can be distributed throughout a microgrid to isolate a faulted branch or faulted branches of an islanded microgrid without interfering with normal fuse operation when the microgrid is connected to the main power grid.

A protection device, externally connectable to an existing circuit breaker with zone selective interlock functionality, enables a circuit breaker to implement directional zone selective interlock. The protection device includes a first input port and a first output port connectable to a circuit breaker, and second and third ports for connecting to a protection device of another circuit breaker and for transmitting interlock signals via an input bus and an output bus inside the EDP. A control unit is configured to enable one of the second and third ports as a second input port and the other as a second output port according to the direction of current currently flowing through the circuit breaker; and configured to forward an interlock signal from the first input port to the output bus and to forward an interlock signal on the input bus received from the second input port to the first output port.

A protection device, externally connectable to an existing circuit breaker with zone selective interlock functionality, enables a circuit breaker to implement directional zone selective interlock. The protection device includes a first input port and a first output port connectable to a circuit breaker, and second and third ports for connecting to a protection device of another circuit breaker and for transmitting interlock signals via an input bus and an output bus inside the EDP. A control unit is configured to enable one of the second and third ports as a second input port and the other as a second output port according to the direction of current currently flowing through the circuit breaker; and configured to forward an interlock signal from the first input port to the output bus and to forward an interlock signal on the input bus received from the second input port to the first output port.

A ZSI testing apparatus includes a fault generation circuit, a plurality of cable assemblies coupled to the fault generation circuit, wherein the cable assemblies are structured to be selectively coupled to selected circuit interrupters, a human machine interface, and a controller coupled. The controller is configured to: (i) selectively cause a fault current to be provided to a number of the cable assemblies, (ii) receive an input from each circuit interrupter that is coupled to one of the cable assemblies, each input being indicative of a trip signal output of the circuit interrupter, (iii) determine based on the received inputs (a) that an error has occurred with respect to operation of the circuit interrupters and (b) a recommendation for fixing the error, and (iv) cause an output indicative of the error and the recommendation to be provided on the human machine interface.

Circuit protection devices, power distribution systems, and methods of monitoring circuit protection devices are described. In one example, a method of monitoring a circuit protection device in a zone selective interlocking (ZSI) system includes monitoring a variable associated with operation of the circuit protection device, determining, based at least in part on the monitored variable, when a likelihood of a malfunction of the circuit protection device exceeds a predetermined threshold, and preventing the circuit protection device from outputting a ZSI blocking signal when the likelihood of the malfunction of the circuit protection device exceeds the threshold.

Circuit protection devices, power distribution systems, and methods of monitoring circuit protection devices are described. In one example, a method of monitoring a circuit protection device in a zone selective interlocking (ZSI) system includes monitoring a variable associated with operation of the circuit protection device, determining, based at least in part on the monitored variable, when a likelihood of a malfunction of the circuit protection device exceeds a predetermined threshold, and preventing the circuit protection device from outputting a ZSI blocking signal when the likelihood of the malfunction of the circuit protection device exceeds the threshold.

A power restoration system comprising a feeder, a plurality of power sources available to provide power to the feeder, a plurality of normally closed reclosing devices electrically coupled along the feeder, at least one normally open recloser electrically coupled to the feeder, and a plurality of normally closed switches electrically coupled along the feeder between each adjacent pairs of normally closed reclosing devices. Each switch is assigned a position code having a value for each of the plurality of power sources that determines when the switch will open in response to the fault current and which power source the switch is currently receiving power from, where timing control between the reclosing devices and the switches allows the switch to be selectively opened to isolate the fault within a single feeder section between each pair of adjacent switches or between each switch and a reclosing device.

Disclosed herein are systems and methods for safe electric power delivery protection within a high-risk area while maintaining electric power availability in non-faulted areas. Fault signals from wireless sensors are used at a recloser to block reclosing onto a faulted high-risk zone. Fault signals from wireless sensors are used at a recloser to permit reclosing when the reclosing operation will not close onto a fault location within the high-risk zone. Portions of the power system may be selectively openable by sectionalizers. When a fault is reported by a wireless sensor as being on a portion of the power system selectively openable, a recloser may be permitted to attempt a reclose operation affecting the high-risk zone and the selectively openable portion.