A device for detecting an arc fault in a polyphase electrical installation comprises: a high-frequency measuring system coupled to at least two electrical phase lines of the installation, said measuring system being configured to extract a first signal representative of high-frequency components of electrical currents flowing through said phase lines; a plurality of low-frequency measuring systems, each coupled to one electrical phase line of the installation, each being configured to acquire a second signal representative of the alternating line current flowing through the corresponding phase line; and a data-processing module programmed to detect an arc fault on the basis of the second signals and of the first signal.

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 device for monitoring and protecting equipment powered by at least one solid-state power controller (SSPC) including at least one current measurement circuit having a current measuring transformer receiving at a primary at least three phases of a three-phase power supply of the equipment, a measuring and testing module including a controller for measuring a current at a secondary I.sub.m, representative of a differential current I.sub.d at the primary, and a channel for injecting current into said transformer, the channel having a current I.sub.inj generator controlled by an output of the controller and connected to an injection winding on the transformer, the injection winding including a number of turns N.sub.in so that the current I.sub.inj produces in said measurement windings a test current I.sub.m of said secondary in the absence of current at the primary.

A device for monitoring and protecting equipment powered by at least one solid-state power controller (SSPC) including at least one current measurement circuit having a current measuring transformer receiving at a primary at least three phases of a three-phase power supply of the equipment, a measuring and testing module including a controller for measuring a current at a secondary I.sub.m, representative of a differential current I.sub.d at the primary, and a channel for injecting current into said transformer, the channel having a current I.sub.inj generator controlled by an output of the controller and connected to an injection winding on the transformer, the injection winding including a number of turns N.sub.in so that the current I.sub.inj produces in said measurement windings a test current I.sub.m of said secondary in the absence of current at the primary.

A method for determining direction of an earth fault (EF) in a feeder of a high impedance grounded power system can be performed by an Intelligent Electronic Device (IED). The method includes obtaining a measure of a first order harmonic active current component derived from residual voltage and current of the feeder when the EF occurred in the feeder, obtaining a measure of a higher order harmonic reactive current component derived from the residual voltage and current of the feeder when the EF occurred in the feeder, and determining the direction of the EF in the feeder based on a combination of the first order harmonic active current component and the higher order harmonic reactive current component.

A cool running ground fault circuit interrupter (GFCI) with radio frequency (RF) noise suppression and a Capacitive Power Supply tbr interrupting the flow of current through a pair of load and neutral lines extending between an input power source and a load is provided. The GFCI includes a pair of switches disposed between the input power source and the load. The switches are actuated by a relay circuit initially powered by a booster circuit and a constant on power supply. A capacitive power supply for cool operation of the GFCI is connected to the load line via a current limiting resistor and provides power to the constant on power supply circuit.

A cool running ground fault circuit interrupter (GFCI) with radio frequency (RF) noise suppression and a Capacitive Power Supply tbr interrupting the flow of current through a pair of load and neutral lines extending between an input power source and a load is provided. The GFCI includes a pair of switches disposed between the input power source and the load. The switches are actuated by a relay circuit initially powered by a booster circuit and a constant on power supply. A capacitive power supply for cool operation of the GFCI is connected to the load line via a current limiting resistor and provides power to the constant on power supply circuit.

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.

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.

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.