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).

An electrical relay system is configured to allow for failure detection of a relay by injecting a signal at a common contact of the relay and looking for the signal at a normally closed contact of the relay. If the relay is commanded to be off, or closed, and the injected signal is not detected through the normally closed contact of the relay, then the system can determine that a failure condition has occurred. In one aspect, the system can include multiple relays with the signal being injected at a common node of the relays. In another aspect, the system can include multiple controllers for controlling and/or monitoring the electrical relay system. The electrical relay system can be coupled to screw terminals for connecting to a field device as part of an industrial automation system.

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.

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.

Provided is a light-emitting element drive device including a transistor control unit arranged to drive and control a transistor connected to a light-emitting element, an output ground fault detection unit arranged to output an output ground fault detection signal corresponding to the voltage level at a connection node between the light-emitting element and the transistor, a stop control unit arranged to stop driving the transistor when the output ground fault detection signal indicates an output ground fault, and a mask signal generation unit arranged to generate a mask signal that masks the output ground fault detection signal on device startup.

A method for single-phase islanding detection in a three-phase electricity network, can include supplying power into a three-phase electricity network (EN) by a power supply assembly (PSA), the electricity network (EN) having a network voltage, and providing a stimulus signal into a positive sequence electric quantity of the electricity network, the positive sequence electric quantity being current, power or a derived quantity thereof. A magnitude and/or a rate of change of an indicative element of a negative sequence component of the network voltage is monitored, a frequency domain of the indicative element including a frequency corresponding to the stimulus signal. A single phase islanding condition is detected in the electricity network (EN) if the magnitude and/or rate of change of the indicative element exceeds a predetermined limit value.

A line break detection system for detecting a break in a conductor (1.004), the system including a first return signal generator (1.020) proximate a first end of a segment of the conductor, the first return signal generator being adapted to apply a first return signal to the conductor, the system including a first return signal detector (1.016) proximate a second end of the segment of the line, the second end being upstream of the first end, the first detector being adapted to receive the first return signal from the line, wherein the first return signal generator ceases to generate the first return signal if the line is broken.

A new approach to Ground Fault Detection and Interruption. The entire DC port is driven with a small-amplitude oscillation or modulation, and the power converter's controller tests for the presence of some version of that signal. If the detected oscillations are too small, either as a result of the GFDI fuse being blown, OR as a result of the DC port having too low of an impedance to ground (ground fault), the circuit detects that and causes the power converter to shut down.

The device comprises at least a first part intended to detect an electrical fault occurring in a network and a second part comprising at least one switch connecting the network to a power supply source, the first part comprising at least one reflectometry detection system capable of being coupled with the network, the system detecting and analyzing the impedance changes occurring in the network, a signal being sent by the system to trigger the opening of the switch when a detected impedance change is considered by the system to be an electrical fault.

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.