Disclosed are a power interruption method and a power interruption device based on a period measurement of an instantaneous power level. The present invention provides a power interruption method and a power interruption device which accurately determine, when a value measured by a current transformer (CT), a voltage detector, etc., is input into a main control unit, whether the measured value is a value equal to or more than a predetermined threshold during a digital analysis processing process to effectively protect a load which receives power by rapid and accurate power interruption for load-side instantaneous overcurrent or overcurrent caused by electric leakage/short-circuit.

An electric circuit device and method is for recognizing a closed switch contact as well as a protective ground conductor interruption in a one- or multiphase electric supply line. A control of a residual current monitoring device (RCMB control) includes one fault current control unit for generating a control signal pattern including a series of switching-on impulses forwarded to a first electronic switch unit to activate a possible artificial passive fault current on one or more active conductors and the protective ground conductor (as a return conductor), this fault current actually flowing, being recognized, and evaluated in a closed circuit in a closed switch contact to be tested and an intact protective conductor. Owing to control signal patterns varying during monitoring, a reliable detection of the artificial passive fault current is ensured even in large dynamic disturbance levels while the electric installation (supply line) to be monitored is in operation.

An electric circuit device and method is for recognizing a closed switch contact as well as a protective ground conductor interruption in a one- or multiphase electric supply line. A control of a residual current monitoring device (RCMB control) includes one fault current control unit for generating a control signal pattern including a series of switching-on impulses forwarded to a first electronic switch unit to activate a possible artificial passive fault current on one or more active conductors and the protective ground conductor (as a return conductor), this fault current actually flowing, being recognized, and evaluated in a closed circuit in a closed switch contact to be tested and an intact protective conductor. Owing to control signal patterns varying during monitoring, a reliable detection of the artificial passive fault current is ensured even in large dynamic disturbance levels while the electric installation (supply line) to be monitored is in operation.

An inverter for a photovoltaic plant including one or more DC electric lines electrically connectable to corresponding photovoltaic strings of the photovoltaic plant. Each DC electric line includes a plurality of line conductors wherein it includes a coupling transformer having a first winding arrangement and a second winding arrangement magnetically coupled with another. The first winding arrangement includes one or more first winding conductors electrically connected with one or more line conductors of a corresponding electric line. The second winding arrangement includes one or more winding conductors magnetically coupled with the first winding conductors and it is adapted to provide first signals indicative of AC currents flowing along the DC electric lines and to exchange second signals along the line conductors of the DC electric lines by exploiting the magnetic coupling with the first winding arrangement.

An inverter for a photovoltaic plant including one or more DC electric lines electrically connectable to corresponding photovoltaic strings of the photovoltaic plant. Each DC electric line includes a plurality of line conductors wherein it includes a coupling transformer having a first winding arrangement and a second winding arrangement magnetically coupled with another. The first winding arrangement includes one or more first winding conductors electrically connected with one or more line conductors of a corresponding electric line. The second winding arrangement includes one or more winding conductors magnetically coupled with the first winding conductors and it is adapted to provide first signals indicative of AC currents flowing along the DC electric lines and to exchange second signals along the line conductors of the DC electric lines by exploiting the magnetic coupling with the first winding arrangement.

The present invention provides a trip control circuit for a circuit breaker capable of breaking a circuit when a fault current occurs due to a DC current component, as well as an AC current. The trip control circuit comprises a current transformer that has a core allowing a circuit to pass through and a secondary coil for detecting a current flowing on the circuit and providing a current detection signal; an oscillation circuit section that configured to apply an electrical signal to the secondary coil to increase a slope of a hysteresis loop of the current transformer to allow the secondary coil to detect a DC current and an AC current; and a trip determining circuit section that configured to compare a current value indicated by the current detection signal with a predetermined reference current value.

Disclosed herein are a variety of systems and methods related to detection of a cross-country fault in an electrical power system. In one embodiment, a system consistent with the present disclosure may be configured to monitor electrical parameters in the electrical power system. The system may determine when a voltage magnitude of one phase exceeds a first voltage threshold. The one phase that exceeds the first voltage threshold may be identified as an un-faulted phase. The system may further be configured to determine that the voltage magnitude of the un-faulted phase exceeds a second threshold based on a zero-sequence voltage. The system may further be configured to determine that a phase angle between the un-faulted phase and the zero-sequence voltage is within a range. A protective action to clear the cross-country fault condition may be implemented upon identification of a cross-country fault.

A temporary power delivery system includes a power source, a booth stringer, and a portable GFCI device. The GFCI device is receives current from the power source by a first terminal and delivers current to the booth stringer by a second terminal. An electronic processor of the GFCI device compares a combined magnitude of current flowing through first and second phase conductors of the GFCI device to a magnitude of current flowing through a neutral conductor of the GFCI. The electronic processor also compares a first voltage between the first phase conductor and neutral conductor to a second voltage between the second phase conductor and neutral conductor. A circuit breaker of the GFCI device is opened if a difference between the combined magnitude of phase conductor current and neutral conductor current exceeds a first threshold or a difference between the first voltage and second voltage exceeds a second threshold.

A method for detecting earth-fault conditions in a power conversion apparatus including the following steps: acquiring a first detection signal indicative of an earth-leakage current flowing between the power conversion apparatus and the ground; processing the first detection signal to calculate a first processing signal indicative of a time variant component of the earth-leakage current for one or more selected frequency bands of interest; processing the first detection signal to calculate a second processing signal indicative of a time-invariant component of the earth-leakage current; processing the first and second processing signals to calculate a third processing signal indicative of a resistive component of the earth-leakage current; and processing the third processing signal to determine whether earth-fault conditions are present.

The invention relates to a method for ascertaining an earth fault and the earth-fault direction in a three-phase network which is operated in a compensated manner or in an insulated manner. Value pairs of a zero voltage and a zero current are measured, the active or reactive energy is calculated, and a voltage flag and a current flag are combined by a Boolean link, wherein the presence of a earth fault is ascertained depending on the result, and a decision is made as to whether the earth-fault direction is signalled as forward or reverse at least on the basis of the sign of the active or reactive energy.