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We propose a ring oscillator (RO) based current-to-voltage-to-frequency (I–V–F) converting current transducer with a cascade bias circuit. The I–V–F converting scheme guarantees highly stable biasing against RO, with a rail-to-rail output operation. This device was fabricated using National NanoFab Center (NNFC) 180 nm complementary metal-oxide-semiconductor (CMOS) technology, which achieves a current resolution of 1 nA in a measurement range up to 200 nA. A noise floor of 11.8 pA/√Hz, maximum differential nonlinearity (DNL) of 0.15 in 1 nA steps, and rail-to-rail output with a 1.8 V power supply is achieved. The proposed transducer can be effectively applied to bio-sensing devices requiring a compact area and low power consumption with a low current output. The fabricated structure can be applied to monolithic-three-dimensional integration with a bio-sensing device.

Autonomous diesel power plants found the active application at the organization of autonomous power supply of the mining enterprises. In article the problem of increase of efficiency of use of control units is considered by the active power of synchronous generators of diesel power plants. As a solution the new innovative offer in the form of the developed device of the measuring converter of active current which is one of the main components of game-trolno-measuring equipment of diesel power plants is offered. The developed scheme is simpler, in comparison with the similar converters of active current executed on the basis of current transformers. In the developed scheme of the measuring converter it is offered to use the differentiating induction converters of current as primary measuring converters. It allows to reduce many times number of the elements entering the standard scheme, and also mass-dimensional characteristics of the device

Facing a lack of high accuracy current standards in the calibration of AC (Alternating Current) + DC (Direct Current) measurement devices that function to measure DC and AC simultaneously, a measurement method with high accuracy is proposed based on zero-flux self-oscillating fluxgate. An iron core and two windings are added onto the single-iron-core double-winding structure of the traditional self-oscillating fluxgate. The added iron core and its upper winding are used to weaken the influence of ripple on the sensor’s accuracy. The other one of the added windings is used for the feedback from the AC+DC magnetic potential, allowing the sensor to work in a zero-flux state and to measure AC+DC simultaneously. An AC+DC transducer prototype with an AC ranging from 0–500 A and DC 0–300 A is developed by selecting the core parameters and an optimized design of the circuit. The test results of the prototype show that the prototype can measure the AC and DC simultaneously, and the measurement accuracy reaches class 0.05 level in the nominal current range. This transducer can be used as a calibration standard of measurement devices for AC only, DC only, or AC and DC simultaneously. Compared with the AC+DC current transducer with the same accuracy level, the proposed transducer has fewer cores and simpler measuring circuit.

Energy efficiency is an important issue in industry, especially with the ever-increasing consumption of electrical energy. The power quality and the traceability of metering devices are essential when integrating energy metering systems for energy efficiency. This management requires an understanding of electrical current events such as pulse and transient currents. Current transducers are widely used to measure these electrical current events up to a few megahertz. Their use makes it possible to measure not only the main current flowing through the transducer, but also the bypass current that affects electrical equipment. Calibration of these sensors up to a few megahertz then becomes an essential step. Currently, most calibration methods are limited to 100 kHz frequency for a current of 10 A. This paper presents an improvement of a traceable calibration methodology for current transducers up to 10 A and 1 MHz, thus increasing, by 10 times, the current level for such high frequency applications. This calibration methodology is based on a metrological traceability chain (uninterrupted link to the International System of Units) with respect to a calculable current shunt and is currently the only traceable method for calibrating current transducers at 10 A and up to 1 MHz. The uncertainty obtained for the transimpedance ratio is less than 0.2%, which is considerably reduced with respect to the existing capabilities.

This paper reports, for the first time, the characterization and measurement accuracy evaluation of a photonic current transducer (PCT) featuring a hybrid fiber Bragg grating/piezoelectric transducer (FBG/PZT) and an integrated passive autoranging (AR) circuit. The enhanced sensor is designed to meet both metering-class (0,2 S) and protection-class (5P15) requirements simultaneously—capabilities not yet demonstrated by any other device in the industry that also supports remote interrogation and multiplexing of multiple sensors. The autoranging technique employs MOSFET switches to dynamically adjust the burden resistance, preventing FBG/PZT voltage saturation during fault or thermal-current events while maintaining adequate sensitivity at lower currents. Experimental results show that integrating the PCT with the passive AR circuit significantly extends the device’s dynamic range, reduces current-measurement errors, and demonstrates potential compliance with both 0,2 S metering- and 5P15 protection-class requirements. The results also confirm that the sensor operates correctly across this extended range.

This paper analyses a special case in evaluating the passive autoranging (AR) technique that dynamically extends the measurement range of a fiber Bragg grating/piezoelectric transducer (FBG/PZT) operating with a current transformer (CT) to realize a dual-purpose metering and protection photonic current transducer (PCT). The technique relies on shorting serially connected burden resistors operating with the CT, using MOSFET switches that react to a changing input current to extend measurement range. The rapid changes in the voltage at the FBG/PZT transducer that are associated with the MOSFET switching are then used on the FBG interrogator side to select the correct measurement range. However, when the MOSFET switching in the AR circuit occurs near the zero-crossing of the input current, the rapid changes in the voltage presented to the FBG/PZT no longer occur, rendering the correct range setting at the interrogator side problematic. The basic switching detection algorithm based on voltage derivative (dV/dt) thresholds proposed in the previous research is not sufficiently sensitive in these conditions, leading to incorrect range selection. To address this, a new detection algorithm based on temporal slope differencing around the zero-crossing is proposed as an additional detection mechanism for these special cases. Thus, the improved hybrid algorithm additionally computes the derivative dV/dt at the FBG/PZT voltage signal within a focused 6 ms temporal window centered around the zero-crossing point, a 3 ms window before and after each zero-crossing instance. It then compares the difference between these two values to a predefined threshold. If the difference exceeds the threshold, a switching event is identified. This method reliably detects even subtle switching events near zero crossings, enabling the accurate reconstruction of the burden current. The performance of the improved algorithm is validated through simulations and experimental results involving zero-crossing switching scenarios. Results indicate that the proposed algorithm improves MOSFET switching detection and facilitates reliable waveform reconstruction without requiring additional hardware.

In this paper, we present a novel technique for passively autoranging a photonic current transducer (PCT) that incorporates a current transformer (CT), piezoelectric transducer (PZT) and fiber Bragg grating (FBG). Due to the usage of single-mode fiber and FBG, multiple PCTs can be interconnected and distributed over a long distance, for example along a power network, greatly reducing the cost of sensor deployment and offering other unique advantages. The autoranging technique relies on the usage of multiple, serially connected CT burden resistors and associated static MOSFET switches to realize instantaneous shortening of the resistors in response to increasing measured current. This functionality is realized passively, utilizing a modular, μW-power comparator circuit that powers itself from the electrical energy supplied by the CT within a small fraction of the 50/60 Hz cycle. The resultant instantaneous changes in sensor gain will be ultimately detected by the central FBG interrogator through real-time analysis of the optical signals and will be used to apply appropriate gain scaling for each sensor. The technique will facilitate the usage of a single PCT to cover an extended dynamic range of the measurement that is required to realize a combined metering- and protection-class current sensor. This paper is limited to the description of the design process, construction, and testing of a prototype passive autoranging circuitry for integration with the PCT. The two-stage circuitry that is based on two burden resistors, 1 Ω and 10 Ω, is used to prove the concept and demonstrate the practically achievable circuit characteristics. It is shown that the circuit correctly reacts to input current threshold breaches of approximately 2 A and 20 A within a 3 ms reaction time. The circuit produces distinct voltage dips across burden resistors that will be used for signal scaling by the FBG interrogator.

This paper reports on the testing and evaluation of a passive autoranging (AR) method designed to dynamically extend the measurement range of a photonic current transducer (PCT) to pave the way toward a realization of a combined metering- and protection-class current sensor. The PCT utilizes a current transformer (CT), a piezoelectric transducer (PZT), and a fiber Bragg grating (FBG) to enable current measurement at multiple points in an electrical power network whereby multiple sensors are deployed and interrogated serially using a single optical fiber. The autoranging technique relies on incorporating static MOSFET switches to instantaneously short individual serially connected CT burdens in response to a measured current magnitude exceeding pre-set thresholds. The AR circuit switching events produce distinctive signal features that are used by the proposed switching algorithm to apply appropriate scaling factors to reconstruct the measured current from the optical signal. It is shown through laboratory experiments that the AR circuit correctly reacts to pre-set burden current thresholds of 130% of the nominal value and 22 times the nominal value, signifying its “metering” and “protection” range boundaries. The circuit reaction time is below 4 ms, rendering it suitable for standard power system protection purposes. Moreover, the operation of the AR circuit is demonstrated for burden currents of up to 100 A for over 1 s, satisfying a test procedure for the secondary CT circuit, as required by some power system operators. It is demonstrated that the proposed switching algorithm allows for a correct reconstruction of the burden currents from the optical signal acquired by the FBG interrogator, offering the potential to realize a dual-class optical current sensor.

Current transducers/transformers have a significant impact on the overall accuracy of the measuring system used for electrical power metering and current measurement, especially in non-sinusoidal conditions. This research concerns an evaluation of the impact of the Rogowski coil and the combined transducer on the distorted current measuring accuracy of the digital power meter. It covers a characterization of their influence in conditions similar, at present, to the high RMS value of the distorted current in order to ensure the required test scenario for the equipment designed for the power network metering purposes. It has been established that the active component—the integration circuit (voltage-to-voltage converter or voltage-to current-converter)—has the most significant effect on the overall performance of the combined transducer. However, its impact is different depending on the selected equipment. Therefore, the presented analysis and results are essential for a conscious choice of the proper current transducer for the substation equipment.

This paper evaluates an electronic current transformer’s wideband accuracy in the transformation of distorted current harmonics. The tests were performed in the range of frequencies from 50 Hz to 5 kHz. The utmost importance was dedicated to the transformation of the low-order higher harmonics. The novelty of this paper involves the analysis of the self-generation of the third and fifth higher harmonics caused by the nonlinearity of magnetic core magnetization characteristics. Therefore, what is considered new in this investigation is that this phenomenon has a significant influence on values of current errors and phase displacements despite the presence of the operational amplifiers and the Hall sensors in the output circuits. Another important factor to consider is the influence of the RMS value of the primary current and output load of the ECT on wideband accuracy. To show the backgrounds of the performed laboratory studies, we also discuss the operation principles of the ECTs with closed and open feedback loops. The accuracy of the tested ECT deteriorated—as with the inductive CT—by the self-generation phenomenon. This resulted in rapid changes in the values of current errors and phase displacements determined for the low-order higher harmonics.