An arc detection system includes an obtainer and a determiner. The obtainer obtains a measurement result for current flowing in a power supply line to which power is supplied from a DC power source. The determiner determines, based on a component of a specific frequency band in the measurement result for the current obtained by the obtainer, whether an arc fault has occurred. The determiner determines that the arc fault has occurred when a specific time for which the component of the specific frequency band is at least a threshold is longer than an occurrence time in which an arc can occur when a device is attached to or detached from the power supply line.

A high-voltage DC floating system includes a source, a power rail, a power bus, a load, and a pre-charge circuit. The power bus includes a positive bus portion and a negative bus portion. The pre-charge circuit includes a first pre-charge circuit portion that is configured to equalize a voltage across the positive power supply switch between the source and a Y-capacitance of the load and a second pre-charge circuit portion that defines a switched path to ground that is configured to equalize a voltage associated with a Y-capacitance of the negative power rail.

A wiring device including an interrupting device, a fault detection device, and a controller. The interrupting device is configured to place the wiring device in a tripped condition in which the flow of power between one or more line terminals and one or more load terminals is interrupted. The fault detection circuit is configured to detect a fault condition and generate a fault detection signal in response to detecting the fault condition, the fault detection signal being provided to the interrupting device to place the interrupting device in the tripped condition. The controller is configured to monitor a current of the one or more line terminals, identify a presence of an in-rush condition or a steady-state condition, and prevent the output of the fault detection signal upon identifying either the in-rush condition or the steady-state condition.

A wiring device including an interrupting device, a fault detection device, and a controller. The interrupting device is configured to place the wiring device in a tripped condition in which the flow of power between one or more line terminals and one or more load terminals is interrupted. The fault detection circuit is configured to detect a fault condition and generate a fault detection signal in response to detecting the fault condition, the fault detection signal being provided to the interrupting device to place the interrupting device in the tripped condition. The controller is configured to monitor a current of the one or more line terminals, identify a presence of an in-rush condition or a steady-state condition, and prevent the output of the fault detection signal upon identifying either the in-rush condition or the steady-state condition.

A composite surge arrester assembly and method of construction protects electrical devices from voltage spikes by limiting the voltage supplied to an electric device by shorting to ground any unwanted voltages above a safe threshold. The composite surge arrester assembly forms an arrester array from an alternating arrangement of deformable conductive contact plates, and metal oxide varistor (MOV) blocks. The contact plates bend and have various types of surfaces to create uniform contact with MOV blocks. The MOV blocks are dimensioned to minimize metal mass. An epoxy impregnated fiberglass reinforcement member wraps around the arrester array at an angle between 0° to 90°, and preferably 45°, relative to the axial disposition of arrester array, while also purging air pockets therebetween. The reinforcement member dampens acoustic shock waves from high current impulses while maintaining electrical contact between MOV blocks. A polymer housing encapsulates the epoxy and fiberglass reinforced arrester array.

A composite surge arrester assembly and method of construction protects electrical devices from voltage spikes by limiting the voltage supplied to an electric device by shorting to ground any unwanted voltages above a safe threshold. The composite surge arrester assembly forms an arrester array from an alternating arrangement of deformable conductive contact plates, and metal oxide varistor (MOV) blocks. The contact plates bend and have various types of surfaces to create uniform contact with MOV blocks. The MOV blocks are dimensioned to minimize metal mass. An epoxy impregnated fiberglass reinforcement member wraps around the arrester array at an angle between 0° to 90°, and preferably 45°, relative to the axial disposition of arrester array, while also purging air pockets therebetween. The reinforcement member dampens acoustic shock waves from high current impulses while maintaining electrical contact between MOV blocks. A polymer housing encapsulates the epoxy and fiberglass reinforced arrester array.

A device (9) for protecting a direct current electrical system (1) having one or more modules (2) from electric arcs comprises: a first sensor (10) provided with a first ring of ferromagnetic material configured to generate a first signal, representing a oscillating component of a current flowing through a cable inserted into the ring; a conditioning stage (12), having a bandpass filter, for conditioning the first signal; a first threshold comparator (13); a counter (15); a processor (14); a second sensor (19), configured to generate a second signal representing a direct current component of the current flowing through the cable; a second threshold comparator (20).

A system for conditioning electric power supplied from a three-phase alternating current electric power supply, including three phase lines, to a load, including the phase lines and an electric ground line, includes a plurality of first surge arresters, a plurality of second surge arresters, a plurality of third surge arresters, a three-phase surge suppressor, and a plurality of capacitors. The surge arresters minimize the amount by which the voltage between two phases and the ground line exceeds a rated value. The three-phase surge suppressor minimizes the amount by which the voltage between any of the three phases and the ground line exceeds a rated value. The capacitors minimize the amount by which the voltage between two phases falls below a rated value.

A system for conditioning electric power supplied from a three-phase alternating current electric power supply, including three phase lines, to a load, including the phase lines and an electric ground line, includes a plurality of first surge arresters, a plurality of second surge arresters, a plurality of third surge arresters, a three-phase surge suppressor, and a plurality of capacitors. The surge arresters minimize the amount by which the voltage between two phases and the ground line exceeds a rated value. The three-phase surge suppressor minimizes the amount by which the voltage between any of the three phases and the ground line exceeds a rated value. The capacitors minimize the amount by which the voltage between two phases falls below a rated value.

Line-mounted devices for determining fault magnitude in an electric power delivery system even under current-transformer (CT) saturation are disclosed herein. Fault magnitude is calculated using unsaturated regions of a current waveform captured by the line-mounted device. The method of determining the unsaturated regions is computationally efficient. Fictitious peaks are removed, and the unsaturated regions are determined based on fractions of the valid peaks. Fault current magnitude is calculated using sample values in the unsaturated regions.