A test and measurement probe system, including an input to receive an input signal, the input signal including a low frequency (LF) and/or direct current (DC) component and an alternating current (AC) component, an extractor circuit, such as an AC coupling circuit or a LF and/or DC rejection circuit, configured to receive the input signal and to separate the AC component and the LF and/or DC component from the input signal, a first output to output the alternating current component to the test and measurement instrument, and a second output to output the direct current component to the test and measurement instrument. In some embodiments, the LF and/or DC component is digitized prior to being output by the second output.

An impedance measurement device of the present disclosure includes: an electrochemical energy device; an amplifier connected to each connection terminal of the electrochemical energy device and configured to amplify a signal introduced into a wiring; and a main board configured to receive the signal from the amplifier and measure an impedance. Accordingly, the present invention has advantages in that high resistance to electromagnetic interference may be achieved by disposing a preamplifier close to a terminal of an electrochemical energy device to amplify only the signal without amplifying a noise introduced into a wiring.

A method for detecting a direct current component in an inductive device, for example in a transformer or choke, includes using a computer for recording an oscillation signal, either of sound emitted from the device or of mechanical oscillation of the device, determining the frequency range of the oscillation signal, determining the value of at least one odd frequency in the frequency range, comparing the value of the odd frequency with the value of at least one even frequency in the frequency range, and determining a direct current component when the value of the odd frequency differs from the even frequency by a predefined amount. The method can be carried out without measuring equipment in the interior of an inductive device and without the involvement of an expert. A computer program product for carrying out the method is also provided.

A method for detecting a contact fault in a photovoltaic system is disclosed. The photovoltaic system includes an inverter and a photovoltaic generator connected to the inverter via DC current lines. The inverter includes a transmitter for coupling a first AC voltage signal having communication frequencies in a first frequency range between 125 kHz and 150 kHz into the DC current lines. A receiver is configured to couple out the first AC voltage signal and is arranged at the photovoltaic generator. A decoupling circuit is configured to decouple the impedance of the photovoltaic generator is arranged between the inverter and the photovoltaic generator, such that the photovoltaic generator is AC decoupled from a transmission path between the inverter and the decoupling circuit. The inverter communicates with the receiver via the first AC voltage signal, and wherein AC currents are measured in the DC current lines and AC voltages are measured between the DC current lines to aid in detection of a contact fault condition.

Systems and methods for mitigating ground induced currents are provided. In one or more examples, the systems and methods can utilize one or more device(s) that can be configured to detect DC currents being induced in and propagated along a power line that is transmitting an AC power signal. In one or more examples the device can be separate the desirable AC power waveform from the undesirable induced DC voltage and determine if the level of induced DC propagating on the power line requires mitigation. In one or more examples, if it is determined that mitigation is required, then the device can be configured to trigger a switch that can be shunt the DC power at the AC waveform zero crossing to a circuit element that is configured to dissipate the undesirable DC current. Filtering can be employed to remove any inadvertent low voltage harmonic distortion. The switch can be triggered during a zero-crossing of the signal to minimize disruption to an end user of the power signal.

Systems and methods for mitigating ground induced currents are provided. In one or more examples, the systems and methods can utilize one or more device(s) that can be configured to detect DC currents being induced in and propagated along a power line that is transmitting an AC power signal. In one or more examples the device can be separate the desirable AC power waveform from the undesirable induced DC voltage and determine if the level of induced DC propagating on the power line requires mitigation. In one or more examples, if it is determined that mitigation is required, then the device can be configured to trigger a switch that can be shunt the DC power at the AC waveform zero crossing to a circuit element that is configured to dissipate the undesirable DC current. Filtering can be employed to remove any inadvertent low voltage harmonic distortion. The switch can be triggered during a zero-crossing of the signal to minimize disruption to an end user of the power signal.

In the field of Rogowski coils for the measurement of current within a conductor there is provided an electrical interface for connection to a Rogowski coil arranged around a primary conductor. The electrical interface includes an input that is configured to sample an input voltage signal from the Rogowski coil. The electrical interface also has an integrator circuit which includes an integrator module that is configured to integrate the sampled input voltage signal to provide an output voltage signal from which can be derived a primary current flowing through the primary conductor. The integrator module employs a transfer function that includes an attenuation factor.

An electronic circuit includes a first peak-hold circuit to output a peak surge voltage free of a ringing component included in a voltage at a voltage input node, a second peak-hold circuit to output a peak surge voltage on which the ringing component included in the voltage at the voltage input node is superimposed, and a subtractor to subtract an output voltage of the first peak-hold circuit from an output voltage of the second peak-hold circuit to output a voltage of the ringing component.

Determining direct current (DC) leakage current flowing through an insulating structure in a high voltage DC power system wherein the DC leakage current is a composite DC current having one or more high magnitude momentary spikes, and having a DC component and an alternating current (AC) component, wherein the AC component has a first rate of change, and wherein the DC component has a second rate of change less than the first, having (a) providing a waveform separator which is configured to receive the composite DC current flowing through the insulating structure and to separate the composite DC current into the corresponding DC component and AC component, and (i) receive at least one corresponding digital signal and the DC component, ii) analyze the at least one corresponding digital signal and the DC component, (iii) determine a resultant leakage current flowing through the insulating structure, (b) electrically connecting the waveform separator to the insulating structure, (c) separating, in the waveform separator, the composite DC current into the corresponding DC component and AC component, (d) receiving the AC component in at least one comparator and producing at least one corresponding digital signal, (e) counting one or more positive AC components in the at least one positive voltage comparator, (f) counting one or more negative AC components in the at least one negative voltage comparator, (g) producing at least one positive digital signal corresponding to the counted one or more positive components and a negative digital signal corresponding to the counted one or more negative components, (h) processing the positive digital signal and the negative digital signal, and the DC component, and determining a resultant leakage current flowing through the insulating structure.

A method, an apparatus, and a device for detecting abnormality of an electric signal. The method includes: sampling the electric signal at each of sampling points in unit sampling intervals, to obtain a sampling value; counting abnormal sampling points within each of the unit sampling intervals to acquire a quantity of abnormal points, where each of the abnormal sampling points is one of the sampling points at which the sampling value is out of a threshold range of the electric signal; determining each of the unit sampling intervals, within which the quantity of abnormal points is larger than a quantity-of-abnormal-point threshold, to be an abnormal unit sampling interval; counting the abnormal unit sampling intervals that are consecutive, to acquire a quantity of consecutive abnormal intervals; and determining that the electric signal is abnormal, in response to the quantity of consecutive abnormal intervals being greater than a quantity-of-abnormal-interval threshold.