A method for identifying element failure in capacitor banks is provided. Capacitor bank phase current is measured and a zero-sequence or negative-sequence current is calculated or measured. A three-phase voltage is measured from a three-phase bus voltage transformer and a zero-sequence voltage or negative-sequence voltage is calculated. A compensated unbalance current is calculated and compared to a predetermined acceptable range. A failure is identified where the compensated unbalance current is outside the predetermined acceptable range.

The invention relates to a method for ascertaining an earth fault and the earth-fault direction in a three-phase network which is operated in a compensated manner or in an insulated manner. Value pairs of a zero voltage and a zero current are measured, the active or reactive energy is calculated, and a voltage flag and a current flag are combined by a Boolean link, wherein the presence of a earth fault is ascertained depending on the result, and a decision is made as to whether the earth-fault direction is signalled as “forward” or “reverse” at least on the basis of the sign of the active or reactive energy.

A safety switch input diagnosis device includes a circuit formed from a series connection of an emergency stop switch and a line having a resistor. A connection state of the emergency stop switch and failure modes of the lines are diagnosed on the basis of a voltage value at one end of the circuit. Consequently, an operation of the switch and failure modes of a circuit relating to the switch can be diagnosed.

A system and method that identify a location and/or magnitude of a ground fault in a circuit having a bus that connects battery strings with loads and a ground reference between the loads are provided. Potential of the bus is shifted relative to a ground reference in a first direction. A first impedance in the bus between the battery strings and the ground reference is determined, and the bus is shifted relative to the ground reference in a second direction. A second impedance in the bus between the battery strings and the ground reference is determined. A location and/or severity of a ground fault is determined based on a relationship between the first impedance and the second impedance.

Various embodiments disclosed herein provide techniques for detecting electrical arcing in an electrical system. A powerline communications (PLC) application executing on a network communications device acquires, via a PLC modem, first voltage readings associated with an electrical circuit. The PLC application performs one or more operations based on the first voltage readings to determine that an electrical arcing condition is present within the electrical circuit. The PLC application performs a remedial operation in response to determining that the electrical arcing condition is present.

A system and method for fault location and isolation in an electrical power distribution network, where the network includes a plurality of switching devices provided along a feeder. The method includes detecting an overcurrent event in the network from the fault and interrupting the overcurrent event by opening and then immediately locking out or subsequently reclosing and testing the fault. A count value is increased in each switching device that detected the overcurrent event. A count and current (C&I) message is sent from each of the switching devices that detected the overcurrent event and then detected the loss of voltage upstream to an upstream neighbor switching device. Current measurements in the C&I messages, measured current by the devices and the counts values in the devices determine what devices are opened to isolate the fault.

A communication-based permissive protection method for protecting an electrical power distribution network from a fault. The network includes a power source, an electrical line and a plurality of fault interrupters, where the fault interrupters are operable to prevent current flow in response to the fault. The method includes detecting the fault by each fault interrupter that is between the fault and the power source, and sending a drop of voltage message from each fault interrupter that doesn't detect the fault, but does detect a drop of voltage as a result of the fault to its immediate upstream fault interrupter. The method opens the fault interrupter that both detects the fault and receives a drop of voltage message from all of the fault interrupters immediately downstream of that fault interrupter.

Systems and methods of determining fault location on a DC microgrid feeder need to be extremely fast to protect the circuit breaker and converter-source components. This disclosure develops a seminal theoretical foundation for fast fault location on a DC feeder that uses only single-ended local measurements in time domain. The theory provides a closed-form deterministic solution for fault location, making the resulting fault location method agnostic to system-topology and immune to fault resistance. The theory is developed with ideal DC voltage sources and is extended to practical converter-sources. The performance of the resulting method is demonstrated by simulating a DC feeder with converters connected at both ends, modeled in PSCAD (power systems computer-aided design).

A system and method that identify a location and/or magnitude of a ground fault in a circuit having a bus that connects battery strings with loads and a ground reference between the loads are provided. Potential of the bus is shifted relative to a ground reference in a first direction. A first impedance in the bus between the battery strings and the ground reference is determined, and the bus is shifted relative to the ground reference in a second direction. A second impedance in the bus between the battery strings and the ground reference is determined. A location and/or severity of a ground fault is determined based on a relationship between the first impedance and the second impedance.

Various embodiments disclosed herein provide techniques for detecting electrical arcing in an electrical system. The techniques include a network device receiving first voltage or current readings associated with a first power cycle, receiving second voltage or current readings associated with a second power cycle, determining that an electrical arcing condition is present by comparing the first voltage or current readings with the second voltage or current readings, and performing a remedial operation in response to determining that the electrical arcing condition is present.