A Rogowski coil is used for determining the magnitude of the electrical current of a conductor of a low-voltage AC circuit, which outputs an analogue voltage which is equivalent to the magnitude of the electrical current of the conductor. The Rogowski coil is connected to an analogue integrator, which is followed by an analogue-digital converter, which converts the integrated analogue voltage into a digital signal which is further processed by a microprocessor in such a way that the phase shift generated by the Rogowski coil and the components connected downstream of the Rogowski coil is compensated such that there are in-phase current values for the detection of error situations in order to protect the low-voltage AC circuit, in particular for a low-voltage power switch or an arc fault detection unit.

A metering and control subsystem for a photovoltaic solar system is configured for metering the photovoltaic solar system using current measurement devices and individually controlling relays to selectively energize photovoltaic branch circuits. In some examples, the metering and control subsystem includes photovoltaic branch connectors, a relay matrix, current measurement devices, and a metering and relay control circuit. The metering and control circuit is configured for metering the photovoltaic solar system using current measurement data from the current measurement devices and individually controlling the relays to selectively energize each photovoltaic branch circuit.

An arc detection device includes: a current detector that includes a magnetic core penetrated by first and second paths and each connecting a DC power source and a device, and detects a current flowing through each of the first and second paths and in accordance with a magnetic field generated at the magnetic core; a low impedance circuit having a lower impedance than the DC power source and the device, the low impedance circuit being connected to the first path and the second path to cause a high frequency component to bypass one of the first path or the second path; and an arc determiner that determines an occurrence of an arc based on a current detected by the current detector. In the magnetic core, a direct current flows through the first path in a direction opposite to a direction in which a direct current flows through the second path.

A power cord includes multiple current-carrying wires covered by an outer insulating layer, each wire including a current-carrying conductor covered by an insulating layer. At least one wire further includes a shield layer covering the insulating layer and a metal conductor between the insulating layer and the shield layer. The shield layer is formed of a band wound around the metal conductor and insulating layer. The outward-facing surface of the band is insulating; the inward-facing surface has one or more conductive regions and one or more insulating regions. One insulating region is located along a longitudinal trailing edge of the band. Consecutive turns of the band partially overlap each other; the trailing edge of a subsequent turn is disposed over part of a previous turn. The structure ensures effective insulation of the metal conductor from other components. The power cord is used in a leakage current detection and interruption device.

A system includes a solid-state circuit breaker coupling between a power supply and an electrical load. The system also includes a gateway interface device communicatively coupled to the solid-state circuit breaker and includes a plurality of communication interfaces. In an embodiment, the gateway interface device includes a controller configured to perform operations including determining a connection status of at least one communication interface of the plurality of communication interfaces and determining a number of devices connected to the at least one communication interface, receive a signal from at least one device of the number of devices. In the embodiment, the operations may also include in response to receiving the signal, instructing the solid-state circuit breaker to disconnect the electrical load from the power supply.

A system and method that identify a location and/or magnitude of a ground fault in a circuit having a bus that connects battery strings with loads and a ground reference between the loads are provided. Potential of the bus is shifted relative to a ground reference in a first direction. A first impedance in the bus between the battery strings and the ground reference is determined, and the bus is shifted relative to the ground reference in a second direction. A second impedance in the bus between the battery strings and the ground reference is determined. A location and/or severity of a ground fault is determined based on a relationship between the first impedance and the second impedance.

An ESD clamp circuit has an ESD detection circuit connected between a first terminal and a second terminal, with a first output node and a second output node. The ESD detection circuit is configured to output respective first and second control signals at the first and second output nodes in response to an ESD event. A discharge circuit includes a p-type transistor having a source, a drain and a gate, with the gate connected to the first output node. An n-type transistor has a source, a drain and a gate, with the gate connected to the second output node. The drain is connected to the drain of the p-type transistor. The discharge circuit is configured to establish a first ESD discharge path from the first terminal, through the p-type transistor and the n-type transistor, to the second terminal, and to further establish a second ESD discharge path in parallel with the first ESD discharge path. The second ESD discharge path includes a parasitic silicon controlled rectifier (SCR).

A diagnostic device includes electrical connectors, load, power supply, switching circuitry, sensors, and processor. The connectors include first and second sets of terminals for connecting to the conductors of a branch circuit in an upstream and downstream direction, respectively, at an outlet location along the circuit. The switching circuitry can isolate the upstream and downstream sections of the circuit from the outlet location, and selectively connect or disconnect the power supply or the load to the upstream or downstream section. The sensors measure electrical characteristics on the conductors of the circuit to monitor load currents, such as on power, neutral and ground lines, of the upstream and downstream circuit sections. The processor controls the switching circuitry, and obtains diagnostic information corresponding to the monitored load currents on the upstream and downstream sections of the branch circuit, from the measurements performed by the sensors.

A series Z-source circuit breaker including a semiconductor switch that breaks source power being provided to a load in response to overcurrent. An electromechanical switch is electrically coupled in parallel with the semiconductor switch, a first capacitor is electrically coupled to an output side of the semiconductor switch, a second capacitor is electrically coupled in parallel with the semiconductor switch, and a delay circuit is electrically coupled in series with the first capacitor. The semiconductor switch is in an open position and the electromechanical switch is in a closed position when overcurrent is not present. Upon detection of overcurrent the semiconductor switch is closed, the electromechanical switch is opened and the delay circuit is controlled to delay when reverse bias current is provided from the first capacitor to the semiconductor switch to prevent source power from being provided to the load to give the electromechanical switch time to open.

In order both to accommodate instantaneous current as well as overcurrent protection in accordance with the load, an overcurrent protection circuit has: a threshold value generation unit that, in accordance with a threshold value control signal, switches between setting an overcurrent detection threshold value to a first set value (∝ Iref) and a second set value (∝ Iset) lower than the first set value; an overcurrent detection unit that compares a sense signal in accordance with the current being monitored and the overcurrent detection value and generates an overcurrent protection signal; a reference value generation unit that generates a reference value (∝ Iset) in accordance with the seconds set value; a comparison unit that compares the sense signal and the reference value, and generates a comparison signal; and a threshold value control unit that monitors the comparison signal, and generates a threshold value control signal.