A method for measuring the impedance of a DUT having a capacitance of less than 1 pF includes applying a voltage or current signal to the DUT, the voltage or current signal including an AC component having a non-zero frequency of less than 1 kHz; monitoring a current or voltage signal, respectively, through the DUT in response to the voltage or current signal; digitizing the voltage signal and the current signal synchronously; and calculating the impedance from the digitized voltage and current signals.

A high voltage isolation tester has a high voltage side and a low voltage side coupled to each other by isolation amplifiers so that the high and low voltage sides are electrically isolated from each other. The high voltage side includes positive and negative high voltage test inputs and a common test input. The high voltage side also includes a positive switched voltage divider network and a negative switched voltage divider network. The low voltage side includes a controller that automatically controls switching of the switched voltage divider networks to make voltage measurements of voltages at inputs of the isolation amplifiers. Outputs of the isolation amplifiers are coupled to inputs of an analog-to-digital converter and the digitized voltages are read from the analog-to-digital converter by the controller.

The present disclosure relates to an insulation resistance measuring device and method, including a parameter resistance connected to a negative electrode terminal of a battery; a shunt resistance connectable to the parameter resistance; a current detection circuit including an operational amplifier configured to detect and output voltage between both ends of the shunt resistance; and a control unit configured to determine the insulation resistance of the battery using a switch control terminal configured to control a switch connected between the parameter resistance and the shunt resistance to an ON or OFF state, a detection signal output terminal configured to selectively apply a first high voltage signal and a first low voltage signal to the shunt resistance, a control signal output terminal configured to apply a control voltage signal to the operational amplifier to adjust an output voltage of the operational amplifier within a predetermined range, an ADC connected to an output terminal of the operational amplifier, and a predefined insulation resistance formula that includes, as a parameter, a first voltage change amount with respect to the output voltage of the operational amplifier being measured through the ADC when the first high voltage signal and the first low voltage signal are applied to the shunt resistance.

The invention relates to a method and a device for identifying arc faults in an ungrounded power supply system. This object is attained by detecting a displacement voltage to ground at an active conductor or at a neutral point of the ungrounded power supply system; by providing a value of an operating frequency occurring in the power supply system; and by analyzing a frequency spectrum of the detected displacement voltage by calculating and assessing Fourier coefficients at the locations of the operating frequency and its harmonics. Due to the broadband detection of the displacement voltage interacting with the “quick” generation of the basic functions by means of a DDS generator, arc faults can be identified reliably in an ungrounded power supply system.

An assembly includes an electrical conductor disposed within an elongate mineral insulated conductive sheath. The electrical conductor is electrically grounded to the conductive sheath. The assembly also includes a test conductor disposed within and electrically isolated from the sheath to provide an indication of the insulation resistance of the assembly.

The present application provides an insulation detection circuit, a method and a battery management system. The circuit includes: a first voltage dividing module, where, one end of the first voltage dividing module is connected to a positive electrode of a power battery to be detected, and the other end of the first voltage dividing module is connected to a first isolation module and a second voltage dividing module respectively; the second voltage dividing module, connected to a negative electrode of the power battery to be detected; the first isolation module, connected to one end of a sampling module; the sampling module, where, the other end of the sampling module is connected to one end of a signal generating module; the signal generating module, where, the other end of the signal generating module is connected to power ground; and the processing module.

Methods and devices are provided for testing the function of a standard insulation monitoring device, installed in an ungrounded power supply system, during operation. The basic concept of the invention rests upon adding a testing apparatus to the ungrounded power supply system, which is being monitored using an insulation monitoring device according to regulations, between the active conductors of an ungrounded power supply system and ground, said testing apparatus systematically changing an insulation resistance of the ungrounded power supply system and observing the reaction of the insulation monitoring device in a fully automated manner in perpetually repetitive testing cycles. The power supply system is monitored perpetually during its operation. In the method, the current operating state (insulation level, load state) of the power supply system is detected via network parameters, such as insulation resistance and system leakage capacity, and consulted for assessing the functionality of the insulation monitoring device.

The invention relates to a circuit assembly (10) for fault detection in an ungrounded high-voltage system (20) having a connected inverter (4) and having at least one resistor (5) between a high-voltage potential (7a, 7b) of the high-voltage system (20) and a reference potential (8), the circuit assembly (10) comprising: a sensing circuit (1), which is designed to tap a voltage from the resistor (5), to generate a first measurement value therefrom and to provide the first measurement value at an output (1c, 1d); and an evaluation device (2), which is connected to the output (1c, 1d) of the sensing circuit (1), the evaluation device (2) being designed to compare the first measurement value with a first limit value and to output a first signal if the first measurement value exceeds the first limit value.

During measuring an insulation resistance for an inverter having at least one half-bridge including two active switching elements for driving an output current, and a DC link voltage, a center point of the half-bridge positioned between the switching elements is connected to a grounding point by closing a grounding switch, and the center point connected to the grounding point is connected, one after the other, to a first ungrounded terminal and a second ungrounded terminal of the DC link voltage of the inverter present at the half-bridge by means of the two active switching elements of the half-bridge to establish a connection between the first and second ungrounded terminals, respectively, and the grounding point. A current flowing via the connection to the grounding point is measured using a measuring device.

The invention relates to a battery system (100) with a battery (20), which is designed to supply a high voltage network (70) with electric energy, and a measuring device (130) for measuring at least one insulation resistance provided between the battery (20) and a housing of the battery (20). The measuring device (130) is equipped with two measuring paths (140, 150), each of which is paired with one of two high-voltage connections (21, 22) of the battery (20), each of which comprises a series circuit that comprises a first resistor (142, 152) and a relay (145, 155), and each of which is connected between the paired high-voltage connection (21, 22) and a point (25) that has a housing potential. Furthermore, each series circuit has a semiconductor switch (147, 157). The measuring device (130) also has two functional modes in which the relays (145, 155) of the measuring paths (140, 150) are closed. When switched to a passive functional mode of the two functional modes, the measuring device (130) is designed to open each semiconductor switch (147, 157) or to keep the semiconductor switch in an open state. When switched to an active functional mode of the two functional modes, the measuring device (130) is additionally designed to alternately open and close the semiconductor switches (147, 157), to measure a first voltage which drops over the first resistor (142, 152) of each measuring path (140, 150) when the semiconductor switch (147, 157) of the corresponding measuring path (140, 150) is closed, and to determine a corresponding insulation resistance of the battery (20) using each measured first voltage.