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 arc detection method includes classifying whether an arc fault is present in the power system by, for each of a plurality of bins of a current frame of a signal, marking the bin as a candidate bin if a magnitude spectrum of the bin meets first criteria; determining a number of candidate bins in the current frame; marking the number of candidate bins as candidate cluster bins if the number of candidate bins exceeds a minimum cluster size; for each of the candidate cluster bins, determining whether the candidate cluster bin is also a candidate cluster bin of a previous frame of the first signal and if so, identifying the current frame as a candidate frame and incrementing a candidate frame count; and if the candidate frame count exceeds a candidate frame count threshold, determining that an arc fault is present in the power system.

In one example, an arc fault circuit interrupter (AFCI) is provided. The AFCI may include a plurality of current arc signature detection blocks configured to output a plurality of corresponding current arc signatures, and a processor. The processor may be configured to receive each of the plurality of current arc signature from each of plurality of current arc signature detection blocks, respectively, and generate a first trigger signal. The processor may be further configured to assess each of the current arc signatures, determine whether an arc fault exists based on the assessment, and generate the first trigger signal if an arc fault is determined to exist. A method for detecting an arc fault is also provided.

An arc detector includes a current sensor, a power spectrum conversion unit that converts an output from the current sensor to a power spectrum, a section value obtaining unit that divides an arc measurement section for the power spectrum into a plurality of regions, and obtains, from region values for the plurality of regions excluding a maximum one of the region values, a region value to be a section value of the arc measurement section, and an arc determination unit that determines a presence of an arc by comparing the section value with a threshold.

The present invention relates to an insulation resistance measuring system and device which calculate resistance values of the positive electrode insulation resistance and the negative electrode insulation resistance by using convergence values of the first voltage and the second voltage, in order to measure the positive electrode insulation resistance and the negative electrode insulation resistance connected to both terminals of a battery pack with a capacitor, respectively.

The present invention relates to a system for diagnosing an insulation element within a battery management system (BMS), in which an input terminal and an output terminal of an insulation element obtain a battery pack diagnosis signal that is output through a battery monitoring circuit and passes through the insulation element, and then abnormality of the insulation element is diagnosed based on a bit operation value of the obtained battery pack diagnosis signal, or an input terminal and an output terminal of the insulation element obtain a transceived communication signal and then abnormality of the insulation element is diagnosed based on a bit operation value of the obtained transceived communication signal.

A fail-safe device is disclosed for ensuring compatibility and reliable operation of a Voltage Indicator System (VIS) for a medium- or high-voltage apparatus in presence of a monitoring system with: a first and second fail-safe device terminal; the first terminal being connectable to an output terminal of a coupler, the coupler being provided in a medium- or high voltage portion of the apparatus, and the second terminal being connectable to an input terminal of the VIS, which is provided in the low-voltage portion; a third and fourth fail-safe device terminal, wherein the third and fourth terminals being electrically connectable to first and second input/output terminals of the monitoring system; and an electrical circuit connecting the first and second fail-safe device terminal and being adapted to compensate for electrical failure modes of the monitoring system such, that the VIS is operable in case the electrical failure modes occur.

A method and device for determining partial discharge in an electrical insulation system of a medium- or high voltage apparatus is disclosed with: detecting, with a sensing unit, an electrical signal that comprises partial discharge pulses due to dielectric breakdowns in the electrical insulation system of the medium- or high voltage apparatus; generating an in-phase and a quadrature-signal from the electrical signal comprising the partial discharge pulses in an I/Q-mixer unit by mixing the electrical signal including the partial discharge pulses with two local oscillator signals having the same frequency and a phase difference of 90; filtering each of the in-phase and the quadrature signals with a low-pass filter; processing the filtered in-phase and the quadrature signals in a processing unit with a low-frequency Analog-Digital converter to obtain digital signals representing an in-phase and a quadrature value.

The present application discloses a method and device suitable to perform the method for operating Voltage Indication system (VIS) and partial discharge module (PD) for medium-voltage or high voltage apparatuses, comprising: monitoring, with the partial discharge-module (PD), provided in low-voltage section, whether partial discharge occurs within a dielectric of the high-voltage or medium-voltage apparatus or system, the partial discharge-module or VIS being electrically connected to a coupler provided in the medium-voltage or high-voltage apparatus; indicating with the Voltage Indication System (VIS), provided in a low-voltage portion, the presence of operating voltages in high-voltage or medium-voltage apparatus or system, Voltage Indication System (VIS) being electrically connected with partial discharge-module (PD) and deactivating by deactivation module connected to Voltage Indication System and partial discharge-module (PD) an optical display in the Voltage Indication System (VIS) during partial discharge measurements.

Methods for assessing cable insulation are provided that can include engaging a first tine gap interdigital capacitor assembly with the exterior of the cable jacket to determine a first capacitance and dissipation factor value of the insulation using the first tine gap interdigital capacitor assembly; engaging a second tine gap interdigital capacitor assembly with the exterior of the cable jacket to determine a second capacitance and dissipation factor value of the insulation using the second tine gap interdigital capacitor assembly. Systems for assessing cable insulation are also provided. The systems can include a cable jacket encompassing cable insulation and conductive material; at least two tine gap interdigital capacitor assemblies engaged with the cable jacket; and processing circuitry operatively engaged with the capacitor assemblies.