An arc fault detection system senses current flow in a power source branch and in one or more load branches in an electrical system. Over a frequency range divided into a predetermined number of frequency bins, a controller records and tallies the branch having largest magnitude of power spectral density for each frequency bin. The branch having highest total tally is determined to be the branch in which the arc fault occurred and can then safely be isolated from the electrical system.

A system includes a dry contact with a first pair of switchable electrodes, a wet contact with a second pair of switchable electrodes, an arc suppressor, and a controller circuit operatively coupled to the arc suppressor and the first and second pairs of switchable electrodes. The controller circuit is configured to detect a failure of the wet contact and determine a stick duration associated with the first pair of switchable electrodes. The stick duration is based on a duration between an instance when a coil of the dry contact is deactivated and an instance of separation of the first pair of switchable electrodes during deactivation of the coil. The controller circuit generates, in-situ and in real-time, health assessment for the first pair of switchable electrodes based on a comparison of the determined stick duration with an average stick duration associated with a window of observation.

In a multi-terminal DC power transmission system, a common control device is connected to a plurality of individual protective devices via a first communication network. Each of the individual protective devices is configured, when detecting change in current or voltage in a corresponding protection zone, to output a fault signal to the common control device via the first communication network and open the corresponding DC circuit breaker such that the corresponding protection zone is disconnected from the multi-terminal DC power grid and deenergized. The common control device estimates a fault occurrence zone where a fault occurs among a plurality of protection zones, based on a plurality of received fault signals. The common control device requests an individual protective device corresponding to a deenergized protection zone of the protection zones excluding the fault occurrence zone to reclose the DC circuit breaker such that the deenergized protection zone is restored.

A system is provided that includes a power transmitter configured to provide power to a current loop, a power receiver configured to receive the power from the current loop. The power receiver is configured to, on a periodic basis, disconnect from the current loop to stop pulling power from the current loop for a period of time to enable a safety check to be performed by the power transmitter. The power transmitter is configured to: monitor current on the current loop; determine whether a current level on the current loop passes the safety check within a predetermined time interval since a determination that the current level was not within a safe range; and control connectivity of the power to the current loop depending on whether the safety check has or has not passed within the predetermined time interval.

A system is provided that includes a power transmitter configured to provide power to a current loop, a power receiver configured to receive the power from the current loop. The power receiver is configured to, on a periodic basis, disconnect from the current loop to stop pulling power from the current loop for a period of time to enable a safety check to be performed by the power transmitter. The power transmitter is configured to: monitor current on the current loop; determine whether a current level on the current loop passes the safety check within a predetermined time interval since a determination that the current level was not within a safe range; and control connectivity of the power to the current loop depending on whether the safety check has or has not passed within the predetermined time interval.

A negative sequence voltage (NSV) protection system is provided that can be added to existing equipment or included as a standalone device for detecting GFOV in electrical configurations connecting distributed energy resources to utility grids. The NSV protection system can be implemented at the low side of a distribution transformer of a typical distribution circuit or in a control system of inverter-based energy resources connected to a distribution feeder. The NSV protection system includes a passive monitoring system that outputs a trip signal when a potential GFOV is detected to occur. The trip signal can then be relayed to open the circuit breakers of a distribution circuit or to cause an inverter-based energy resource to trip offline.

A negative sequence voltage (NSV) protection system is provided that can be added to existing equipment or included as a standalone device for detecting GFOV in electrical configurations connecting distributed energy resources to utility grids. The NSV protection system can be implemented at the low side of a distribution transformer of a typical distribution circuit or in a control system of inverter-based energy resources connected to a distribution feeder. The NSV protection system includes a passive monitoring system that outputs a trip signal when a potential GFOV is detected to occur. The trip signal can then be relayed to open the circuit breakers of a distribution circuit or to cause an inverter-based energy resource to trip offline.

A system of surge suppressor units is connected at multiple locations on a power transmission and distribution grid to provide grid level protection against various disturbances before such disturbances can reach or affect facility level equipment. The surge suppressor units effectively prevent major voltage and current spikes from impacting the grid. In addition, the surge suppressor units include various integration features which provide diagnostic and remote reporting capabilities required by most utility operations. As such, the surge suppressor units protect grid level components from major events such as natural geomagnetic disturbances (solar flares), extreme electrical events (lightning) and human-generated events (EMPs) and cascading failures on the power grid.

A system of surge suppressor units is connected at multiple locations on a power transmission and distribution grid to provide grid level protection against various disturbances before such disturbances can reach or affect facility level equipment. The surge suppressor units effectively prevent major voltage and current spikes from impacting the grid. In addition, the surge suppressor units include various integration features which provide diagnostic and remote reporting capabilities required by most utility operations. As such, the surge suppressor units protect grid level components from major events such as natural geomagnetic disturbances (solar flares), extreme electrical events (lightning) and human-generated events (EMPs) and cascading failures on the power grid.

An electrical system includes an operation MEMS switch operable in on and off states to enable and disable current flow to a load and a fault interruption MEMS switch positioned in series with the operation MEMS switch. The fault interruption MEMS switch is operable in on and off states to enable and disable current flow to the electrical load, with operation of the fault interruption MEMS switch in the off state disabling current flow to the load regardless of the state of the operation MEMS switch. A fault sensor control system operate to sense a system variable, analyze the system variable to detect if a fault is affecting the electrical system and, upon detection of a fault, switch the fault interruption MEMS switch from the on state to the off state to interrupt current flowing through the operation MEMS switch to the load.