scholarly journals Influence of the Selection of the Core Shape and Winding Arrangement on the Accuracy of Current Transformers with Through-Going Primary Cable

Energies ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1932
Author(s):  
Elzbieta Lesniewska
Keyword(s):  
Current Transformer ◽  
Analytical Models ◽  
Current Transformers ◽  
Accuracy Class ◽  
Real Model ◽  
Current Error ◽  
Location Change ◽  
Measurement Location ◽  
Physical Phenomena ◽  
Metrological Requirements

The current transformers with split-core are used for installation in places where it is impossible to install classic current transformers. Moreover, this design allows for any measurement location change, and even switching one current transformer into several different shapes of bars or cables. Power network operators, striving for more accurate current measurements, require producers to provide current transformers with a special accuracy class 0.2S. Therefore, manufacturers and designers try to meet the market requirements and, similarly to non-demountable current transformers, i.e., with a toroidal core, design current transformers with split-core class 0.2S. To meet the high metrological requirements, 3D analyses of electromagnetic fields were performed, taking into account physical phenomena and not approximate analytical models. Two types of cores and four different arrangements of the secondary windings of the measuring current transformers were considered. The magnetic field distributions, current error, and phase displacement diagrams of all current transformer models were analyzed, and the model of the transformer structure with the best accuracy was selected. Computations were conducted based on the finite element numerical method, and the results were compared with the real model tests.

scholarly journals The calculate of current transformers with combined magnetic cores

2021 ◽  
Vol 296 ◽  
pp. 02004
Author(s):  
Andrey Batrashov ◽  
Olga Stepanskaya
Keyword(s):  
Magnetic Properties ◽  
Safety Factor ◽  
Current Transformer ◽  
Type Material ◽  
Rational Model ◽  
Current Transformers ◽  
Accuracy Class ◽  
Design Constraints ◽  
Flexible Approach ◽  
Magnetic Cores

The manufacture of current transformers is associated with many design constraints, which include the restricted dimensions of its installation places, requirements for the accuracy class, as well as the limitation on the safety factor or the minimum factor of the accuracy limit factor. In a design sense of current transformers, these requirements are contradictory, which resulting in a flexible approach to the manufacture of current transformers. The use of combined magnetic cores can be referred to one of these areas, in other words magnetic cores consisting of materials with different magnetic properties, which allows to obtain unique magnetic properties that are inaccessible when using magnetic cores of the same type (material), thus providing a rational model of production. The article presents a feature of calculating of current transformer with combined magnetic cores.

scholarly journals The Method to Determine the Turns Ratio Correction of the Inductive Current Transformer

Energies ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 8602
Author(s):  
Ernest Stano
Keyword(s):  
Correction Factor ◽  
Current Transformer ◽  
Frequency Characteristics ◽  
Magnetization Curves ◽  
Current Transformers ◽  
Current Error ◽  
Ratio Correction ◽  
Secondary Winding ◽  
Load Conditions ◽  
Load State

This paper presents the method for evaluation of the turns ratio correction of the inductive current transformer using the magnetization curves determined at the non-load state and in the load conditions. The presented method may be applied to determine even a fractional winding correction factor. The standard IEC 61869-2 provides the method to determine the turns ratio correction of the tested CT from the measured rms values of voltages on its primary and secondary winding in the non-load state. However, this approach is limited in determining the significant changes in the number of turns of the secondary winding. Moreover, the paper presents the influence of the applied turns ratio correction on the frequency characteristics of the current error and phase displacement of the inductive current transformers evaluated for the transformation of the distorted current.

Design and Analysis of PCB Rogowski Coil Current Transformer

2014 ◽  
Vol 672-674 ◽  
pp. 984-988
Author(s):  
Biao Su ◽  
Li Xue Li ◽  
Yi Hui Zheng ◽  
Xin Wang ◽  
Yan Liu ◽  
...  
Keyword(s):  
Power System ◽  
High Sensitivity ◽  
Current Transformer ◽  
Rogowski Coil ◽  
Electromagnetic Current ◽  
Current Transformers ◽  
Coil Current ◽  
Electronic Current ◽  
Rogowski Coils ◽  
Electronic Current Transformers

Electronic current transformers are more suitable for the development of power system compared with traditional electromagnetic current transformers. Rogowski coil current transformer is one of three electric current transformers. According to the measurement principle of Rogowski coils, the equivalent circuit of PCB Rogowski coils is analyzed. By using four PCB Rogowski coils combined, a PCB Rogowski coil current transformer is designed and tested. The results show that the designed PCB Rogowski coil transformer has good linearity and high sensitivity and measurement accuracy and it can meet the requirement of power system.

Simulation Model for Assessing Operational Performance of Current Transformers

2007 ◽  
Vol 18-19 ◽  
pp. 71-77
Author(s):  
I. Sule
Keyword(s):  
Simulation Model ◽  
Current Transformer ◽  
Operational Performance ◽  
Current Transformers ◽  
Correct Operation ◽  
Operational Conditions ◽  
Secondary Current ◽  
Protection Scheme ◽  
The Core ◽  
Instrument Transformers

In determining the correct operation of relays of a protection scheme, proper representation of instrument transformers and their behavior in conditions where there can be saturation, is very critical. The main objective of this paper is to develop simulation model for assessing the operational performance of Current Transformer (CT). In order to test the validity of the developed model, three cases of CT operational conditions were considered, with data collected from Gombe, 330/132/33kV PHCN substation. The simulation results revealed various configuration performance responses that could affect relay protective schemes to different degrees. The CT responses revealed that the secondary current and voltage were distorted when the core flux linkages exceeded the set 9.2 pu saturation limit. It is concluded that the model developed for the CT of interest yield satisfactory results.

Error Calculating and Compensating Method of All-Optical Fiber Current Transformer in ± 10 kV DC Distribution Network

2019 ◽  
Vol 14 (11) ◽  
pp. 1606-1615
Author(s):  
Jicheng Yu ◽  
Changxi Yue ◽  
Jun Li ◽  
Dengyun Li ◽  
He Li
Keyword(s):  
Optical Fiber ◽  
Distribution Network ◽  
Current Transformer ◽  
Electromagnetic Current ◽  
Current Transformers ◽  
Wave Plate ◽  
Remote Transmission ◽  
Dc Distribution ◽  
All Optical ◽  
Database Technology

Current transformer is one of the main equipment in ±10 kV DC distribution network. Traditional electromagnetic current transformer has poor anti-jamming capacity and poor insulation, so it cannot realize transient protection. The emergence of all-optical fiber current transformer brings solutions to these problems, which has attracted more and more attention. In this study, aiming at the problem of error and compensation of λ/4 waveform of all-fiber current transformer, the fabrication method of λ/4 waveform is studied, the mathematical model of the waveform is established, the influence of the waveform error on the scale factor is analyzed, and a calculating device of angle difference and ratio difference to compare the error is designed. The device adopts the principle of traceability of quantities to collect the state data of the wave plate. At the same time, in order to collect data for errors, database technology and network technology are used to realize remote transmission of monitoring data. The error of the λ/4 wave plate is compensated, the bidirectional principle generated by the birefringence in the fiber ring is analyzed, and the data logic description of the transformer sensitive ring is performed. The phase delay and the angle of the shaft are selected as the main factors causing the error. Compensation is performed by means of peak segmentation and variable cancellation. In the experimental process, compared with the error sampling of the traditional transformer, the error calculated by the current amplitude and phase angle parameters obtained by the all-fiber current transformer is more accurate, and the compensation scheme can suppress the size of the birefringence and improve sensing accuracy of fiber optic current transformers. This study provides a powerful reference for the error analysis of all-fiber current transformer λ/4 wave plates, which is beneficial to promote the better application of such current transformers.

Simulation and Analysis for Current Transformers with DC Bias and Remnant Flux

2013 ◽  
Vol 765-767 ◽  
pp. 2430-2434
Author(s):  
Xiao Qian Tian ◽  
Bao Shu Li ◽  
Lu Shen
Keyword(s):  
Error Compensation ◽  
Current Transformer ◽  
Scientific Basis ◽  
Current Transformers ◽  
Ratio Error ◽  
Full Wave ◽  
Accuracy Of Measurement ◽  
Dc Bias ◽  
Power Metering ◽  
Fourier Algorithm

The transfer characteristics of current transformers (CT) change due to DC bias, which directly impacts the accuracy of measurement and power metering. Based on equivalent circuit models and core magnetizing characteristic, qualitatively analysis current transformer saturation increase errors of CT. Transfer errors under DC bias and remnant flux are also obtained based on J-A model of CT in PSCAD/EMTDC and full-wave Fourier algorithm to show that the ratio error and phase displacement increase with the DC bias. Based on FFT spectrum analysis to identify remnant flux and DC bias provides scientific basis for error compensation of CT.

DESIGN AND TEST OF A NEW HIGH-CURRENT ELECTRONIC CURRENT TRANSFORMER WITH A ROGOWSKI COIL

2014 ◽  
Vol 21 (1) ◽  
pp. 121-132 ◽  
Author(s):  
Ming Zhang ◽  
Kaicheng Li ◽  
Shunfan He ◽  
Jun Wang
Keyword(s):  
Dynamic Range ◽  
Partial Evaluation ◽  
Current Transformer ◽  
Rogowski Coil ◽  
High Current ◽  
Current Transformers ◽  
Electronic Current Transformer ◽  
Electronic Current ◽  
Electro Magnetic ◽  
Electronic Current Transformers

Abstract This paper describes the design and test of a new high-current electronic current transformer based on a Rogowski coil. For better performances, electronic current transformers are used to replace conventional electro-magnetic inductive current transformers based on ferromagnetic cores and windings to measure high-current on the high voltage distribution grids. The design of a new high-current electronic current transformer is described in this paper. The principal schemes of the prototype and partial evaluation results are presented. Through relative tests it is known that the prototype has a wide dynamic range and frequency band, and it can allow high accuracy measurements.

scholarly journals Annual particle flux observations over a heterogeneous urban area

2009 ◽  
Vol 9 (20) ◽  
pp. 7847-7856 ◽  
Author(s):  
L. Järvi ◽  
Ü. Rannik ◽  
I. Mammarella ◽  
A. Sogachev ◽  
P. P. Aalto ◽  
...  
Keyword(s):  
Land Use ◽  
Urban Area ◽  
Emission Factor ◽  
Particle Number ◽  
Analytical Models ◽  
Flux Measurements ◽  
Median Particle ◽  
Particle Fluxes ◽  
Measurement Location ◽  
Annual Scale

Abstract. Long-term eddy covariance particle number flux measurements for the diameter range 6 nm to 5 μm were performed at the SMEAR III station over an urban area in Helsinki, Finland. The heterogeneity of the urban measurement location allowed us to study the effect of different land-use classes in different wind directions on the measured fluxes. The particle number fluxes were highest in the direction of a local road on weekdays, with a daytime median flux of 0.8×109 m−2 s−1. The particle fluxes showed a clear dependence on traffic rates and on the mixing conditions of the boundary layer. The measurement footprint was estimated by the use of both numerical and analytical models. Using the crosswind integrated form of the footprint function, we estimated the emission factor for the mixed vehicle fleet, yielding a median particle number emission factor per vehicle of 3.0×1014 # km−1. Particle fluxes from the vegetated area were the lowest with daytime median fluxes below 0.2×109 m−2 s−1. During weekends and nights, the particle fluxes were low from all land use sectors being in the order of 0.02–0.1×109 m−2 s−1. On an annual scale the highest fluxes were measured in winter, when emissions from stationary combustion sources are also highest. Particle number fluxes were compared with the simultaneously measured CO2 fluxes and similarity in their sources was distinguishable. For CO2, the median emission factor of vehicles was estimated to be 370 g km−1.

scholarly journals Use of statistical analysis methods in processing population survey data

2021 ◽  
pp. 58-60
Author(s):  
Vasilij Kalinchik ◽  
Vitaliy Pobigaylo ◽  
Vitaliy Kalinchyk ◽  
Daniil Filjanin
Keyword(s):  
Total Error ◽  
Current Transformer ◽  
Measuring Channel ◽  
Measuring Circuit ◽  
Metrological Characteristics ◽  
Measuring Instruments ◽  
Voltage Transformer ◽  
Current Transformers ◽  
Collection Device ◽  
Communication Lines

The article analyzes the structures of the measuring channels of electricity metering systems. It is shown that such a structure is determined by the types of measuring instruments used and the scheme of their connection, in particular, by the types of electricity meters installed at the metering points. Moreover, the counters can have a pulse or interface information output. It is shown that the path for measuring and metering electricity includes a measuring circuit consisting of measuring current and voltage transformers, an electricity meter, communication lines, a metering device and a data collection device. The applied method is based on the standardization of the metrological characteristics of individual elements of the measuring path and their synthesis based on the metrological characteristics of the entire electricity metering system. To calculate the total error of the measuring channel, a formula is used that takes into account only the errors of the measuring circuit. It is shown that in recent years there has been a tendency when measuring current transformers and, accordingly, electricity meters operate in the mode of low current loads. In this case, the errors of the elements of the measuring path are poorly studied. The graphs of errors of current transformers depending on load currents are given. It is shown that the values of the errors of current transformers vary with the magnitude of the load current and are in the region of negative values. Therefore, the wrong choice of current transformers can lead to a significant underestimation of electricity. The errors of voltage transformers depend mainly on the load on the secondary winding and do not significantly affect the total error. The resulting error of the measuring path current transformer - voltage transformer - electricity meter in the area of low loads is given. A change in errors in the area of low loads leads to serious metrological losses (underpayment of electricity). In the automation of electricity metering, graphs of changes in errors in the area of low loads are presented, which can serve as a basis for correcting the error of the measuring paths.

scholarly journals A Multisensor System for the Characterization of the Field Pressure in Terrain. Accuracy, Response, and Adjustments

Sensors ◽  
2019 ◽  
Vol 19 (18) ◽  
pp. 3942
Author(s):  
Isabel Sicilia ◽  
Sofía Aparicio ◽  
Borja Frutos ◽  
Eduardo Muñoz ◽  
Margarita González ◽  
...  
Keyword(s):  
Concrete Slab ◽  
Pressure Sensors ◽  
Temporal Response ◽  
Generator System ◽  
Multisensor System ◽  
Motion System ◽  
Transport Studies ◽  
Real Model ◽  
In Series ◽  
Physical Phenomena

In different disciplines of science, the knowledge of the resulting pressures in the subsoil can help to understand physical phenomena of mass exchange between the atmosphere and the terrain. The measurement of lower differential pressures is complicated given the low range of detected values. In this paper, a multisensor system has been designed and developed to measure differential pressures in radon gas transport studies. The adequacy of this system has been proven using a purpose-built pressure chamber and an automatic motion system developed by the authors. The temporal response frequencies, the pressure values measured by the sensors, and their ability to link in series were analyzed to offer a multisensor spatial and temporal mapping. At the same time, the influence of the components required for a real deployment were studied using different tube lengths and diameters, connectors, and obstructions across the operating range of the pressure sensors. The system has also been tested for measuring differential pressures in a real model with a concrete slab above the soil and a pressure generator system below. It was found that this system is very suitable for outdoor measurements that demand a quick temporal response and accuracy.

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