A device is presented for use in power distribution networks, for limiting transient overvoltages during backfeed on a network primary feeder whose feeder breaker is open and whose network protector fails to open. The device is self-contained and self-protecting, and limits the transient voltages due to an arcing single line-to-ground fault by inserting a resistance into the zero-sequence network of the primary feeder. Limiting transient overvoltages reduces damage to and prevents failures of various network components, and in particular, prevents multiple insulation failures during backfeed and reduces failures during backfeed in microprocessor network protector relays on the secondary side of network transformers whose protectors are open. In addition, the device reduces transient overvoltages associated with re-energizing a network primary feeder by closing the station breaker when all network protectors on the feeder are open, as occurs when restoring a network primary feeder that has been out of service.

A device is presented for use in power distribution networks, for limiting transient overvoltages during backfeed on a network primary feeder whose feeder breaker is open and whose network protector fails to open. The device is self-contained and self-protecting, and limits the transient voltages due to an arcing single line-to-ground fault by inserting a resistance into the zero-sequence network of the primary feeder. Limiting transient overvoltages reduces damage to and prevents failures of various network components, and in particular, prevents multiple insulation failures during backfeed and reduces failures during backfeed in microprocessor network protector relays on the secondary side of network transformers whose protectors are open. In addition, the device reduces transient overvoltages associated with re-energizing a network primary feeder by closing the station breaker when all network protectors on the feeder are open, as occurs when restoring a network primary feeder that has been out of service.

A differential protection method for monitoring a line of a power grid. Current phasor measured values are captured at the ends of the line and transmitted to an evaluation device which is used to form a differential current value with current phasor measured values temporally allocated to one another. Time delay information indicating the time delay between local timers of the measuring devices is used for the temporal allocation of the current phasor measured values captured at different ends, and a fault signal indicating a fault affecting the line is generated if the differential current value exceeds a predefined threshold value. The reliability of the time synchronization is further increased by forming a quotient of the current phasor measured values to form an asymmetry variable, that is used to check a transit time difference of messages transmitted via the communication connection in different directions.

A matrix converter includes one or more current sensors structured to sense current flowing through the matrix converter, a matrix of switches including a number of solid state transistors, and a control circuit structured to detect faults in power flowing through the matrix converter based on the sensed current, to control the matrix of switches to drive an external device, and to control the matrix of switches to switch to prevent power from flowing internal to the matrix converter, or external to the external device in response to detecting a fault in power flowing through the matrix converter.

A sensor includes a passage in a shield with a clear width of 25.2 to 32 mm, which provides a higher sensitivity to electrical differential current, and more particularly for determining the universal-current sensitive determination of an electric differential current. The sensor can be a part of a circuit breaker, a charging cable and a charging station.

A sensor includes a passage in a shield with a clear width of 25.2 to 32 mm, which provides a higher sensitivity to electrical differential current, and more particularly for determining the universal-current sensitive determination of an electric differential current. The sensor can be a part of a circuit breaker, a charging cable and a charging station.

A temporary power delivery system includes a power source, a booth stringer, and a portable GFCI device. The GFCI device is receives current from the power source by a first terminal and delivers current to the booth stringer by a second terminal. An electronic processor of the GFCI device compares a combined magnitude of current flowing through first and second phase conductors of the GFCI device to a magnitude of current flowing through a neutral conductor of the GFCI. The electronic processor also compares a first voltage between the first phase conductor and neutral conductor to a second voltage between the second phase conductor and neutral conductor. A circuit breaker of the GFCI device is opened if a difference between the combined magnitude of phase conductor current and neutral conductor current exceeds a first threshold or a difference between the first voltage and second voltage exceeds a second threshold.

A power conversion apparatus includes a power conversion circuit configured to convert DC power into three-phase AC power; and a control device configured to generate a two-phase negative-phase current from a three-phase AC current output from the power conversion circuit, and to detect an open phase on an output side of the power conversion circuit based on a magnitude of an amplitude of the two-phase negative-phase current. The control device may be configured to determine an occurrence of the open phase when the magnitude of the amplitude of the two-phase negative-phase current increases, and an electric current of at least one phase of the three-phase AC current decreases.

A multiphase ground fault circuit interrupter includes a first phase power line input, a second phase power line input, a third phase power line input, a neutral line input, a controller circuit having a relay control output, a first phase latching relay having a first phase switch input coupled to the first phase power line input and a first phase relay control input coupled to the relay control output of the controller circuit, a sensor having a core and a sensor pickup coupled to the controller circuit, and a first phase load wire coupled to a first phase switch output of the first phase latching relay and passed through the core.

A multiphase ground fault circuit interrupter includes a first phase power line input, a second phase power line input, a third phase power line input, a neutral line input, a controller circuit having a relay control output, a first phase latching relay having a first phase switch input coupled to the first phase power line input and a first phase relay control input coupled to the relay control output of the controller circuit, a sensor having a core and a sensor pickup coupled to the controller circuit, and a first phase load wire coupled to a first phase switch output of the first phase latching relay and passed through the core.