A DC power distribution system has power sources, a DC power distribution bus with DC bus sections. The system has power switching assemblies to couple one of the DC bus sections to another and a system controller. An inverter is connected to one of the power switching assemblies to supply a consumer. The first and second terminals are electrically coupled to first and second bus sections. First and second semiconductor devices between the terminals control current flow and there is a current connection from each terminal to a power switching assembly controller for providing an indication of current. A control signal line is connected between the power switching assembly controller and each semiconductor device provides a signal to the semiconductor devices to control the current flow and an inverter coupler couples each current connection to the inverter. The inverter coupler has a feed from each current connection to the inverter.

Disclosed is a power control system for preemptive detection and prevention of electric disasters including a feed end that supplies power, a receiver end that receives the power from the feed end through a line, a power control device that calculates at least one of a loss power value, a leakage current value, a voltage drop value, and an impedance value based on a voltage value and a current value, which are measured at each of the feed end and the receiver end, detects whether the line is abnormal, by comparing the calculated at least one value with a corresponding predetermined threshold and identifying a change in electrical properties, and controls the power supplied to the receiver end when it is detected that the line is abnormal.

Apparatuses and methods herein provide a voltage imbalance detector that employs two solenoid coils, each coil coaxially arranged around a slidable metal plunger on opposite sides thereof. One coil is electrically connected to one line of a 120 V/240 V power supply and to neutral, while the other coil is electrically connected to the other line of the 120 V/240 V power supply and to neutral. When the coils are energized by current from the power supply, each coil induces an equal but opposite electromagnetic force acting on the metal plunger if the power supply voltages are balanced, thereby maintaining the plunger stationary relative to the coils. But if the voltages are not balanced, then one coil will induce a greater (or lesser) electromagnetic force than the other coil, resulting in the plunger moving toward (or away from) the first coil, thereby sensing the voltage imbalance.

Apparatuses and methods herein provide a voltage imbalance detector that employs two solenoid coils, each coil coaxially arranged around a slidable metal plunger on opposite sides thereof. One coil is electrically connected to one line of a 120 V/240 V power supply and to neutral, while the other coil is electrically connected to the other line of the 120 V/240 V power supply and to neutral. When the coils are energized by current from the power supply, each coil induces an equal but opposite electromagnetic force acting on the metal plunger if the power supply voltages are balanced, thereby maintaining the plunger stationary relative to the coils. But if the voltages are not balanced, then one coil will induce a greater (or lesser) electromagnetic force than the other coil, resulting in the plunger moving toward (or away from) the first coil, thereby sensing the voltage imbalance.

There is provided a method of operating a reconfigurable differential protection scheme for carrying out differential protection of an electrical power network, the electrical power network comprising terminals, each of the terminals configured to be in communication with each other within a communications network. The method includes controlling the differential protection scheme to deactivate the differential protection, and selecting a terminal to be configured out of or into the differential protection scheme. The method also includes communicating reconfiguration information among the terminals, the reconfiguration information including the selection of the terminal to be configured out of or into the differential protection scheme. The method also includes modifying a respective differential protection algorithm at each of the non-selected terminals so as to configure the selected terminal out of or into the differential protection scheme, and controlling the differential protection scheme to reactivate the differential protection.

A method of current differential protection performed in a control device is disclosed, wherein the control device has a first operate-restrain characteristic with a differential characteristic pick-up setting I.sub.D. The method includes: determining currents of all terminals of a protected object; determining a differential current based on the determined currents; determining direct current, DC, components in the respective determined currents; detecting a fault; and adjusting, for a detected external fault, the operate-restrain characteristics by setting an adjusted differential characteristic pick-up setting I.sub.D.sub._.sub.adj to be equal to the sum of the differential characteristic pick-up setting I.sub.D and the determined DC components, providing an adapted operate-restrain characteristics. Corresponding control device, computer program and computer program product are also disclosed.

A differential protection method monitors a line of an electrical energy supply network. Current signals are generated at the ends of the line using inductive current transformers, which current signals are proportional to a current flowing at the respective end. For each end, current measurement values are formed from the respective current signal using measuring devices, which current measurement values indicate a profile of the current flowing at the respective end. For each end, a respective charge value is determined from the current measurement values. The charge values of all the ends are summed to form a charge sum, and a fault signal that indicates an internal fault on the line is generated when the charge sum exceeds a charge threshold value. To perform line differential protection in the case of current transformer saturation, when transformer saturation of a current transformer is present, an estimated charge value is ascertained.

The disclosed methods and systems employ a nonprobability-based detection scheme that measures conditions (e.g., voltage or current) at multiple locations on a circuit, such as a branch circuit, to detect for a presence of an arc fault condition. A centralized processing system, such as a controller (120), receives information corresponding to a branch origin voltage or current measurement sensed by a sensor (114, 116) at a branch origin upstream of the plurality of end-use devices (150) on the branch circuit (e.g. at a circuit breaker defining the branch), and receives information corresponding to a downstream voltage or current measurement at each of the end-use devices sensed by a corresponding downstream sensor (152, 154).

The disclosed methods and systems employ a nonprobability-based detection scheme that measures conditions (e.g., voltage or current) at multiple locations on a circuit, such as a branch circuit, to detect for a presence of an arc fault condition. A centralized processing system, such as a controller (120), receives information corresponding to a branch origin voltage or current measurement sensed by a sensor (114, 116) at a branch origin upstream of the plurality of end-use devices (150) on the branch circuit (e.g. at a circuit breaker defining the branch), and receives information corresponding to a downstream voltage or current measurement at each of the end-use devices sensed by a corresponding downstream sensor (152, 154).

Passive monitoring the integrity of current sensing devices and associated circuitry in GFCI and AFCI protective devices is provided. A protection circuit interrupter employs a capacitively coupled noise signal obtained by an arrangement of one or both of line side arms relative to a Rogowski coil. The noise signal is monitored while the line and load sides of a protective circuit interrupter are disconnected, and the connection of the line and load sides disabled if the noise signal fails to correlate sufficiently to a reference noise cycle. When the line and load sides are connected, the RMS value of the observed current signal is monitored such that the line and load sides are disconnected if the observed current signal fails to meet an RMS threshold. The observed current signal is compensated by subtracting the reference noise cycle prior to monitoring for the fault condition applicable to the protective device.