Dynamically monitoring of an electrically-isolated power bus for a DC power system is described, and includes dynamically monitoring voltage and current on the power bus to determine a variation in the voltage on the power bus. When the variation in the voltage on the power bus is less than a threshold, an active positive isolation resistance term and an active negative isolation resistance term are determined. A first voltage balance term is determined based upon a ratio of the active positive isolation resistance term and the active negative isolation resistance term. A dynamic positive isolation resistance term and a dynamic negative isolation resistance term are determined based upon the active negative isolation resistance term. A fault associated with the power bus is determined based upon the dynamic positive isolation resistance term and the dynamic negative isolation resistance term.

A ground fault detection device connected to a high-voltage battery and a positive electrode side Y capacitor includes: a detection capacitor operating as a flying capacitor, a first switch and a first resistor connecting a positive electrode side of the high-voltage battery and one end of the detection capacitor in series, and a discharge circuit including at least a discharge capacitor. The discharging circuit has one end connected to the positive electrode side of the high-voltage battery and an another end connected to the negative electrode side of the high-voltage battery. The discharge circuit further includes: a fifth switch that connects one end of the discharge capacitor and the positive electrode side Y capacitor, and a second discharge resistor and an eighth switch that connect the another end of the discharge capacitor and the ground in series.

It is disclosed an insulation impedance detection circuit and detection method of a photovoltaic inverter system. The photovoltaic inverter system includes one or more input circuits and an inverter circuit, each of the input circuit electrically coupled to the inverter circuit through a positive bus and a negative bus, with a first equivalent impedance R.sub.p between the positive bus and a protective earth point and a second equivalent impedance R.sub.n between the negative bus and the protective earth point. The detection circuit includes: a bus voltage sampling circuit coupled to the positive bus and the negative bus for generating a first bus voltage and a second bus voltage; a protective earth voltage sampling circuit coupled to the protective earth point for generating a first protective earth voltage and a second protective earth voltage; and a controller for calculating an equivalent insulation impedance.

It is described an electrical installation measuring system comprising a control and measuring device configured to be installed on an electrical panel of an electrical installation and perform at least one measure of an electrical parameter of the electrical installation depending on an electrical load connected to the electrical installation and transmit command signals along a telecommunication link. The system further comprises a variable load device connectable to the electrical installation and configured to: receive the command signals from the telecommunication link; and assume a plurality of load configurations according to the command signals.

A circuit arrangement (20) having an active measuring voltage (U.sub.G) for determining an insulation resistance (R.sub.F) or a complex-valued insulation impedance (Z.sub.F) of an ungrounded power supply system (12) against ground potential (PE), the circuit arrangement (20) having a measuring path (24) which runs between an active conductor (L1, L2) of the power supply system (12) and the ground potential (PE) and includes a measuring-voltage generator (V.sub.G) for generating the measuring voltage (U.sub.G), a measuring resistance (R.sub.M) for capturing a measured voltage (U.sub.M) and a coupling resistance (R.sub.A), the circuit arrangement (20) having a signal evaluation circuit (26) which includes a signal input for evaluating the measured voltage (U.sub.M) and a ground connection (GND). The ground connection (GND) is connected to a ground potential (PE).

A method for detecting an isolation fault in an isolation resistance between a positive and negative high-voltage bus rail and a vehicle chassis on a high-voltage propulsion side of a high-voltage system of an electric or hybrid-electric vehicle. The high-voltage system is split into a battery side and propulsion side by means of two high-voltage contactors located in the positive and negative high-voltage bus rails. The propulsion side includes first and second capacitors connected in series across the positive and negative bus rails, a common junction of the first and second capacitors connected to the chassis. The method supplies a low-voltage output to the positive and negative bus rails to charge the capacitors; and determines, based on charging current, voltage level or energy level of the capacitors, whether an isolation fault is present between the positive and/or negative high-voltage bus rail and the vehicle chassis on the propulsion side.

A combined monitoring device for insulation-resistance monitoring and protective-conductor-resistance monitoring in a power supply system includes a grounded power supply system and an ungrounded power supply system, the combined monitoring device having a coupling circuit for being coupled to one or several active conductors of the grounded power supply system via coupling points, the combined monitoring device including an active monitoring device with a first operating mode for monitoring an insulation resistance in an ungrounded network state of the power supply system and a second operating mode for monitoring a protective-conductor resistance in a grounded network state of the power supply system, the combined monitoring device having an evaluation unit switchable between the first and second operating modes as a function of the ungrounded or grounded network state and configured for testing the insulation resistance in the first operating mode and the protective-conductor resistance in the second operating mode.

The invention relates to a device and a method for insulation monitoring including identification of a faulty outer conductor in a three-phase ungrounded power supply system. The fundamental idea of the present invention rests upon determining the phase angle between the measured mains voltage and the measured neutral-point voltage when presuming only one measurement of the mains voltage to ground at one of the outer conductors and one measurement of the neutral-point voltage to ground. The value of the thus determined phase angle is in one of three angle ranges which each extend over 120 degrees and are to be assigned to one of the three outer conductors so that the faulty outer conductor is determined. The faulty outer conductor is thus detected by measuring only one mains voltage in conjunction with the measurement of the neutral-point voltage by evaluating the phase between the two measured voltage.

A method and device for determining a division of a total insulation resistance and of a total system leakage capacitance in an ungrounded power supply system. The basic idea is to determine how the total insulation resistance is divided into partial insulation resistances and how the total system leakage capacitance is divided into partial system leakage capacitances between the active conductors of the ungrounded power supply system from displacement voltages measured between each of the active conductors of the ungrounded power supply system based on values determined in advance for the total insulation resistance and for the total system leakage capacitance of the ungrounded power supply system. By evaluating the displacement voltages in terms of their changes in amplitude, their frequency and their phasing, conclusions can be drawn as to the division of the total insulation resistance and of the total system leakage capacitance between the individual active conductors.

The present disclosure provides an insulation detection circuit, a detection method and a battery management system. The insulation detection circuit includes an isolated power module, first positive and negative sampling modules, second positive and negative sampling modules, and a processor. A first end of the second positive sampling module is connected to a positive electrode of the isolated power module and a second end of the positive switch module, a second end of the second positive sampling module is connected to a second reference voltage terminal; a first end of the second negative sampling module is connected to the second reference voltage terminal, a second end of the second negative sampling module is respectively connected to a negative electrode of the isolated power module and a second end of the negative switch module; and the processor is connected to sampling points.