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 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.

Protection circuitry configured to protect an electrical load from both overvoltage and overcurrent and includes a recovery period timer configured to set a recovery time. The recovery time allows a system, including a power supply, voltage regulator, protection circuitry and electrical load to dissipate heat and reset components. The protection circuitry is configured to monitor downstream performance of the electrical load and disconnect upstream power based on a downstream failure or other performance characteristics. The protection circuitry may include a downstream overvoltage sensing circuit that controls a current source. The current source injects current into an overcurrent protection loop in the protection circuitry that includes the configurable recovery period timer. In this manner both an overvoltage and an overcurrent event may take advantage of the configurable recovery period timer without the need for a separate time delay circuit.

In a multi-phase power grid fed by a power source, earth fault (460) is located by means of a power supply source synchronized with the power grid, which is connected between a zero point of the grid and earth. In a fault current compensation mode (420), a control unit controls the alternating voltage source to compensate for any ground fault current in the power grid to a value below a threshold level. In a fault detecting mode (430), the control unit gradually adjusts the output voltage of the alternating voltage source with respect to amplitude and/or phase angle (440). A change of zero-sequence current and zero-sequence admittance between the alternating voltage source and a fault location is measured (450) by means of at least one detector. The at least one detector is communicatively connected to the control unit and reports recorded measured values representing zero-sequence current and/or zero-sequence admittance to the control unit. In the fault detecting mode, the control unit localizes a ground fault (460) based on at least one of said measurement values representing changes of the zero-sequence current and/or zero-sequence admittance, upon which an affected branch is disconnected (470) or the system switches to the fault compensation mode (420).

A neutral grounding resistor fault protection arrangement. The fault protection arrangement may include a neutral grounding resistor, the neutral grounding resistor comprising a ground end and a non-ground end; a sense circuit, coupled to the non-ground end of the neutral grounding resistor; and a neutral grounding monitor, coupled to the non-ground end of the neutral grounding resistor, the neutral grounding monitor comprising an injection signal generator, the injection signal generator arranged to generate a frequency of 240 Hz or greater.

In a bridge circuit, a series circuit in which a first resistor and a second resistor are connected in series and the second resistor and a fourth resistor are connected in series is formed. In the bridge circuit, the series circuit is connected to a load portion in parallel, one end of a fifth resistor is connected between the second resistor and the fourth resistor, and the other end of the fifth resistor is connected between the first resistor and the load portion. In the bridge circuit, a voltage supply unit is connected between the first resistor and the second resistor. A controller detects an abnormality of the load portion based on a detection voltage of the bridge circuit detected by applying a voltage from the voltage supply unit with a switch turned off. With this configuration, an abnormality detection device can detect abnormality while suppressing an increase in size.

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.

The present invention relates to current measurement apparatus. The current measurement apparatus comprises first and second measurement devices with each of the first and second measurement devices being operative to measure current in a respective one of a live conductor and a neutral conductor substantially simultaneously. The current measurement apparatus is operative to make plural different determinations in dependence on the substantially simultaneous current measurements.

A power source is proposed comprising an output for a load. The power source is configured to provide a first voltage at the output. The power source is configured to detect a feedback at the output. The power source is further configured to provide a second voltage at the output based on the detected feedback. A high second voltage is only provided if an appropriate load is detected. This has the advantage that people are protected from electric shock e.g. when handling unconnected cables.

An electrical link (8) between a DC high-voltage power source (2) and a user apparatus (5) including: an electrical conductor (4) surrounded by an insulating cover (4a), and an electrical protection device (3) that includes a conductive sleeve (7) arranged around the insulating cover (4a), a current generator (10) connected to a current injection point (30) of the conductive sleeve (7), a circuit breaker (9) arranged on the conductor and configured to cut off a current transiting through the conductor (4), and a detection module (11) connected to a current tap-off point (31) of the conductive sleeve (7) and to the circuit breaker (9) and configured to detect a current leak out of the conductor (4) and command the circuit breaker (9).