An arrangement for injection-based ground fault protection handling including a number of stator windings of an electric machine that are connected to a neutral point, a first transformer including at least one primary winding connected to at least one measurement point of the stator windings and at least one secondary winding for measuring an electrical quantity of the machine at the measurement point. There is also a second transformer having a primary winding connected between the neutral point and a ground potential and a secondary winding for connection to a signal generation and detection unit in order to inject a signal into the neutral point and receive a response. The impedance of the second transformer is in the range of the impedance of the machine.

An electrical link includes an electrical protection device. The electrical link, for linking an AC high-voltage generator to a user apparatus, includes an electrical conductor surrounded by a first inner insulating envelope. An electrical protection device includes a conductive sheath around the inner insulating envelope. A fixed DC current generator is connected to a current injection point of the conductive sheath. A circuit breaker that can be activated is on the electrical conductor and configured to break the electrical link when it is activated. A detection module is connected to a current tap-off point of the conductive sheath and to the circuit breaker, the detection module being configured to detect a break in the conductive sheath, a current leak out of the electrical conductor or a current leak out of the sheath and to activate the circuit breaker.

A circuit for mitigating electric shock including an external impedance detection circuit and a test and holdoff circuit. The external impedance detection circuit detects a presence of an external impedance, such as by detecting a relative change in voltage from a startup condition and a test condition. The test and holdoff circuit inhibits operation of a power converter which delivers power to be consumed by a load. The startup condition is defined by mains power applied to the circuit with negligible power consumed by a load. The test condition is defined by non-zero power delivered to the load. According to another aspect, the external impedance detection circuit measures an input voltage using a high input power which is greater than a shock hazard threshold at a duration less than a threshold time duration and determines the presence of the external impedance based on low pass filters having different time constants.

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.

The method detects a fault in a power switching electronic device (OT.sub.1) by using the thermo-acoustic effect and comprises the steps of: a) detecting an acoustic signal (SA) generated by thermo-acoustic effect in the electronic device when it is in operation; determining (FFT) a frequency spectrum of the detected acoustic signal and obtaining, from the frequency spectrum, a spectral signature (SEP) associated with the detected acoustic signal; comparing (CSG) the spectral signature (SEP) with a plurality of reference spectral signatures (Sgn); and, deciding (CSG) on the presence of at least one fault in the electronic device when at least one coincidence is identified in the comparison step c) between the spectral signature and the plurality of reference spectral signatures.

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 test signal is applied from a continuity test source to a photovoltaic (PV) panel string, to test electrical continuity in the PV panel string and between the PV panel string and an inverter that is coupled to the PV panel string. If the test signal is detected at a PV panel disconnect switch that is separate from the continuity test source and switchably couples one or more Direct Current (DC) PV panels in the PV panel string, then the PV panel disconnect switch is controlled to connect the one or more DC PV panels in the PV panel string. Otherwise, the PV panel disconnect switch is controlled to disconnect the one or more DC PV panels from the PV panel string. The test signal could be, for example, an Alternating Current (AC) signal tuned to a PV installation that includes the PV panel string and the inverter.

In one embodiment, an aircraft electronics system includes a hardware processor, a charge collection circuit to collect charge; a switching circuit controlled by the hardware processor to discharge the charge collected on the charge collection circuit through a bonding circuit formed from a chassis and a bonding surface; and a voltage measurement circuit to measure a voltage difference between measurement terminals across the chassis and the bonding surface.

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.

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.