Passive monitoring the integrity of current sensing devices and associated circuitry in GFCI and AFCI protective devices is provided. A protection circuit interrupter employs a capacitively coupled noise signal obtained by an arrangement of one or both of line side arms relative to a Rogowski coil. The noise signal is monitored while the line and load sides of a protective circuit interrupter are disconnected, and the connection of the line and load sides disabled if the noise signal fails to correlate sufficiently to a reference noise cycle. When the line and load sides are connected, the RMS value of the observed current signal is monitored such that the line and load sides are disconnected if the observed current signal fails to meet an RMS threshold. The observed current signal is compensated by subtracting the reference noise cycle prior to monitoring for the fault condition applicable to the protective device.

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.

Passive monitoring the integrity of current sensing devices and associated circuitry in GFCI and AFCI protective devices is provided. A protection circuit interrupter employs a capacitively coupled noise signal obtained by an arrangement of one or both of line side arms relative to a Rogowski coil. The noise signal is monitored while the line and load sides of a protective circuit interrupter are disconnected, and the connection of the line and load sides disabled if the noise signal fails to correlate sufficiently to a reference noise cycle. When the line and load sides are connected, the RMS value of the observed current signal is monitored such that the line and load sides are disconnected if the observed current signal fails to meet an RMS threshold. The observed current signal is compensated by subtracting the reference noise cycle prior to monitoring for the fault condition applicable to the protective device.

Passive monitoring the integrity of current sensing devices and associated circuitry in GFCI and AFCI protective devices is provided. A protection circuit interrupter employs a capacitively coupled noise signal obtained by an arrangement of one or both of line side arms relative to a Rogowski coil. The noise signal is monitored while the line and load sides of a protective circuit interrupter are disconnected, and the connection of the line and load sides disabled if the noise signal fails to correlate sufficiently to a reference noise cycle. When the line and load sides are connected, the RMS value of the observed current signal is monitored such that the line and load sides are disconnected if the observed current signal fails to meet an RMS threshold. The observed current signal is compensated by subtracting the reference noise cycle prior to monitoring for the fault condition applicable to the protective device.

Signal transducers in electrical communication with shorted leads of current transformers are used to provide monitoring and protection functions to an electric power delivery system. Differential protection is performed by comparing a predetermined threshold against a voltage signal from series-connected leads of signal transducers in electrical communication with shorted leads of current transformers. The signal transducers may be Rogowski coils. Signal transducers in communication with shorted leads may be used to improve safety and increase performance of the current transformers by decreasing susceptibility to saturation.

In a circuit breaker arrangement, this disclosure describes a method and circuit design enables a current transformer to be used to detect ground faults in circuit breakers (such as a main-tie-main circuit breakers) that have been designed to receive signals from Rogowski coils.

A method for locating and clearing phase faults in a micro-grid in off-mode. The method includes determining a surveillance area of a microgrid having at least two busbars to monitor; determining all source feeders and load feeders of the surveillance area; acquiring measurement data comprising current magnitude for all source feeders and load feeders; and monitoring the at least two busbars in the surveillance area for a voltage dip in one of phase-to-phase or phase-to-neutral voltages. The method further includes, on detecting a voltage dip on the monitored busbars, determining a defect phase having a minimum phase-to-neutral voltage; and performing current analysis for the defect phase.

A power converter includes first and second arms, each having switching elements, and performs power conversion between a DC system and an AC system. An AC circuit breaker and a current control circuit are connected in series between the AC system and the power converter. The current control circuit includes a current-limiting resistor and a disconnector connected in parallel. A controller instructs a disconnector to close after an initial charge of the power converter and opens the AC circuit breaker when an impedance of a line between a first node located on a first end side of the current control circuit and a second node located on a second end side of the current control circuit is not less than a first threshold and an accumulated value of a current flowing through the current control circuit within a certain period of time is not less than a second threshold.

A power system includes: a self-commutated power converter including a first arm and a second arm, each including switching elements; a first circuit breaker configured to interrupt a current flowing through a power transmission line provided between a first bus and a second bus; a first circuit breaker control unit configured to control the first circuit breaker; a converter control unit configured to stop the switching elements based on a first arm current value and a second arm current value; and a setting unit configured to set a voltage value of an AC voltage output from the power converter such that when a fault occurs in the power transmission line, the first circuit breaker is opened while the switching elements are not stopped. The converter control unit is configured to operate the switching elements such that an AC voltage with the set voltage value is output.