A DC arc fault detection module includes an LF current section, an LF voltage section, and an HF current section having a plurality of outputs, each output being associated with a respective one of a plurality of frequency sub-bands. The HF current section is structured to, for each of the frequency sub-bands, (i) detect a rise in energy of the frequency sub-band above a first predetermined threshold level for at least a certain amount of time and (ii) cause the associated output to indicate a rise in energy detection in response to detecting the rise in energy above the associated threshold level for at least the associated certain amount of time. The module includes a processing device structured to determine whether a DC arc fault has occurred based on the outputs from the LF and HF current and LF voltage sections.

In a circuit breaker arrangement, this disclosure describes a method and circuit design enables a current transformer to be used to detect ground faults in circuit breakers (such as a main-tie-main circuit breakers) that have been designed to receive signals from Rogowski coils.

A measurement module uses harmonic compensation factors to minimize the effects of harmonic distortion in measurements of a source current by a current sensor of the module. The module samples at a first sampling rate, measurements of the source current to generate a first current measurement. The module samples at a second sampling rate higher than the first sampling rate, for an interval of time, measurements of the source current to generate a second current measurement. The module determines a harmonic compensation factor based, at least, on a difference between the first current measurement and the second current measurement. The module determines a reported current computed as a function of at least the first current measurement, the difference between the first current measurement and the second current measurement, and the harmonic compensation factor. The reported current represents a magnitude of the source current adjusted by the harmonic compensation factor.

A method for monitoring the state of an electric machine includes determining within a defined frequency range, for example in a spectrogram of a current amplitude, a frequency position where a current amplitude has a maximum at the frequency position and where a phase relationship between a current vector and a voltage vector or between two current vectors is located in a predefined interval. The determined frequency position is characteristic; of the state of the electric machine.

The invention relates to a measurement system for detection of conduction faults of a device or equipment, comprising an evaluation unit and at least one sensor unit, wherein the measurement system is furthermore adapted to determine, in regard to a fault, whether the fault is higher or lower in frequency with respect to a predetermined limit frequency, and the measurement system is furthermore adapted to provide data in regard to one fault or multiple faults.

Example embodiments of the invention include a powdered core bead body configured to become an inductive impedance to current signals with high frequencies in a power wire threaded through the powdered core bead body. The signals are detectable by a high frequency voltage sensor that is configured to output an arc fault tripping indication to an arc fault tripping circuit in response to an occurrence of high frequency current signals in the power wire.

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 radiation hardened current sensor to sense direct current (DC), low frequency alternating current (AC), and high frequency AC includes a DC current transformer (DCCT) including a primary DCCT winding and a secondary DCCT winding. A self-oscillating modulator is coupled to the secondary DCCT winding of the DCCT to maintain a magnetic flux density of the DCCT at an upper limit and a lower limit of a magnetic hysteresis characteristic of the DCCT. An active filter passes only the DC and the low frequency AC from the DCCT as an output. An AC current transformer (ACCT) including a primary ACCT winding and a secondary ACCT winding. The output of the active filter is coupled to the ACCT and the secondary ACCT winding provides the high frequency AC.

A current sensor system for accurately measuring an AC electrical current having frequencies up to 2 kHz, the system comprising: an electrical conductor (e.g. busbar) for conducting said AC current thereby creating a first magnetic field; a magnetic sensor device for measuring a magnetic field component or gradient; an object (e.g. a metal plate) having an electrically conductive surface arranged in the vicinity of said conductor for allowing eddy currents to flow in said surface, thereby creating a second magnetic field which is superimposed with the first magnetic field; wherein the magnetic sensor device is configured for determining the current as a signal or value proportional to the measured component or gradient. The metal plate may have an opening. The current sensor system may further comprise a shielding.

Embodiments disclosed herein include a sensor. In an embodiment, the sensor comprises a board, wherein an aperture is formed through the board, a current loop winding through the board around the aperture, and a voltage ring around the aperture and within an inner perimeter of the current loop, wherein the voltage ring comprises an interior ring, an insulator ring around the interior ring, and an exterior ring around the insulator ring.