A method of detecting a serial arc fault in a DC-power circuit includes injecting an RF-signal with a narrow band-width into the DC-power circuit and measuring a response signal related to the injected RF-signal in the DC-power circuit. The method further includes determining a time derivative of the response signal, analyzing the time derivative, and signaling an occurrence of a serial arc fault in the power circuit based on the results of the analysis. A system for detecting an arc fault is configured to perform a method as described before.

An electronic device having an overcurrent protection function is provided. The electronic device includes at least one power converter, the at least one power converter including a power conversion unit to convert input voltage or input current to supply output current, a control unit to adjust the output current, and an overcurrent protection unit to detect the output current and transmit a detection result to the control unit, and wherein the overcurrent protection unit includes an overcurrent extraction module to output a difference between the output current exceeding designated first reference current and the first reference current; a calculation module to calculate an accumulative value obtained by integrating the difference with respect to time, and a first comparison module to compare the accumulative value with a designated critical value and to transmit a first detection result in which the accumulative value exceeds the critical value to the control unit.

A method of detecting a serial arc fault in a DC-power circuit includes injecting an RF-signal with a narrow band-width into the DC-power circuit and measuring a response signal related to the injected RF-signal in the DC-power circuit. The method further includes determining a time derivative of the response signal, analyzing the time derivative, and signaling an occurrence of a serial arc fault in the power circuit based on the results of the analysis. A system for detecting an arc fault is configured to perform a method as described before.

A system for ground fault detection includes an alternating current (AC) excitation source configured to provide an AC test signal to a circuit under test; a current transformer configured to detect a current of the AC test signal; a capacitive pickup configured to detect a voltage of the AC test signal; and a receiver which includes a display; and a processor configured to receive the voltage from the capacitive pickup; receive the current from the current transformer; and display on the display one or more components of the current.

Aspects of the disclosure provide for a circuit. In some examples, the circuit includes a first current source having a terminal coupled to a first node and a second terminal, a first switch coupled between the second terminal of the first current source and a second node, a first resistor coupled between the second node and a ground terminal, a second current source having a terminal coupled to the first node and a second terminal, a second switch coupled between the second terminal of the second current source and a third node, a second resistor coupled between the third node and the ground terminal, a third current source having a terminal coupled to the first node and a second terminal, a third switch coupled between the second terminal of the third current source and a fourth node, and a third resistor coupled between the fourth node and the ground terminal.

Aspects of the disclosure provide for a circuit. In some examples, the circuit includes a first current source having a terminal coupled to a first node and a second terminal, a first switch coupled between the second terminal of the first current source and a second node, a first resistor coupled between the second node and a ground terminal, a second current source having a terminal coupled to the first node and a second terminal, a second switch coupled between the second terminal of the second current source and a third node, a second resistor coupled between the third node and the ground terminal, a third current source having a terminal coupled to the first node and a second terminal, a third switch coupled between the second terminal of the third current source and a fourth node, and a third resistor coupled between the fourth node and the ground terminal.

A system and method for controlling microgrids composed of inverter-based distributed generation (IBDG) units. This includes a method using multiple IBDGs to inject impedance-modulated harmonic currents during fault conditions, with each IBDG injecting a unique, differentiable harmonic (i.e., non-fundamental) order from neighboring IBDGs. The method also involves using an inverse time-harmonic-current characteristic to detect faults by locally measuring the harmonic currents injected by IBDGs. A harmonic directional overcurrent relay is also used for fault detection.

A computing device includes a module that connects to a main board and a short detector. The short detector applies a voltage to a first electrical contact of the module; while the voltage is applied: makes a comparison of a second voltage on a second electrical contact of the module to the voltage; makes a determination, based on the comparison, that the first electrical contact is connected to the second electrical contact via a short circuit; and in response to the determination, initiates remediation of the short circuit.

A leakage current detection and protection device includes a leakage current detection module for generating a detection feedback signal when detecting a leakage current on the power supply lines, wherein the power supply lines supply a working power to the leakage current detection module during half of the AC power cycles; a self-test module for testing whether the leakage current detection module is faulty based on the detection feedback signal, which includes: a simulated leakage current generating circuit for generating a simulated leakage current signal; a fault signal generating module for generating a self-test fault signal when the leakage current detection module has a fault; and a self-test compensation module for supplying an auxiliary working power to the leakage current detection module so the leakage current detection module is in a working state whenever the simulated leakage current is generated. This prevents misjudgment by the leakage current detection module.

The invention relates to an electric circuit arrangement and a method for coupling an insulation monitoring device to an ungrounded power supply system via a coupling impedance, which is realized to be operant for each active conductor of the power supply system and which is formed as an ohmic resistance circuit, the ohmic resistance circuit having a settable resistance value which is changeable and a switching-off function for decoupling the insulation monitoring device from the network and being realized as a bidirectional cascade comprising a series circuit of two transistors provided in a mirror-inverted manner, each having a diode connected in parallel, a controlled change in resistance of the transistors for setting the changeable resistance value being effected by a control circuit and the switching-off function for decoupling from the grid being realized by setting a maximum resistance value.