scholarly journals Measuring the Voltage Dependence of Current Transformers

2020 ◽  
Author(s):  
Helko van den Brom ◽  
Ronald van Leeuwen ◽  
Gert Rietveld ◽  
Dennis Hoogenboom
Keyword(s):  
Leakage Current ◽  
High Voltage ◽  
Voltage Dependence ◽  
Current Transformers ◽  
Ratio Error ◽  
Phase Displacement ◽  
Hv Cable

A setup has been developed to determine the voltage dependence of the ratio error and phase displacement of current transformers (CTs) used for medium- or high-voltage (HV) applications. A shielded HV cable is used to protect the reference CT for the voltage applied to the CT under test. As a first step, a method was developed to determine and correct for the effect of the leakage current through this cable on the ratio error and phase displacement of the reference CT for voltages up to 24 kV.

scholarly journals Measuring the Voltage Dependence of Current Transformers

2020 ◽  
Author(s):  
Helko van den Brom ◽  
Ronald van Leeuwen ◽  
Gert Rietveld ◽  
Dennis Hoogenboom
Keyword(s):  
Leakage Current ◽  
High Voltage ◽  
Voltage Dependence ◽  
Current Transformers ◽  
Ratio Error ◽  
Phase Displacement ◽  
Hv Cable

A setup has been developed to determine the voltage dependence of the ratio error and phase displacement of current transformers (CTs) used for medium- or high-voltage (HV) applications. A shielded HV cable is used to protect the reference CT for the voltage applied to the CT under test. As a first step, a method was developed to determine and correct for the effect of the leakage current through this cable on the ratio error and phase displacement of the reference CT for voltages up to 24 kV.

Measurement of Ratio Error and Phase Displacement of DC Tolerant Current Transformers

2007 ◽  
Vol 5 (1) ◽  
pp. 289-292 ◽  
Author(s):  
Pavel Mlejnek ◽  
Petr Kašpar ◽  
Karel Draxler
Keyword(s):  
Current Transformers ◽  
Ratio Error ◽  
Phase Displacement

scholarly journals Metrological characterisation of current transformers calibration unit for accurate measurement

ACTA IMEKO ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 6
Author(s):  
Valentyn Isaiev ◽  
Oleh Velychko
Keyword(s):  
Measurement Uncertainty ◽  
Current Phase ◽  
Measuring Instruments ◽  
Current Transformers ◽  
Sources Of Uncertainty ◽  
Ratio Error ◽  
Phase Displacement ◽  
Measurement Results ◽  
The Difference ◽  
Detailed Presentation

<p class="Abstract"><span lang="EN-US">The manuscript presents a method for the metrological characterisation of the commercial AC comparators used to calibrate current transformers. The theoretical basis for simulating the difference between two almost identical currents has been outlined, as well as the mathematical models for both a ratio error and a phase displacement has been derived. The measurement setup, consisting of conventional measuring instruments, has been described with a detailed presentation of its parameters. The sources of uncertainty have been distinguished and analysed with determining the current phase shift which led to a significant increase of relative measurement uncertainty. The simulation of measurement results was yielded in two ways: physically using a method presented and virtually using a Monte Carlo method. The second method confirmed that evaluating the measurement uncertainty through derived sensitivity coefficients is correct enough. The simulation results in the range from 1 to 1200 parts per million for both ratio error and phase displacement motivated the use of a comparator characterised through the proposed method for accurate measurement, especially for very low errors.</span></p>

scholarly journals Modeling Stray Capacitances of High-Voltage Capacitive Dividers for Conventional Measurement Setups

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1262
Author(s):  
Alessandro Mingotti ◽  
Federica Costa ◽  
Lorenzo Peretto ◽  
Roberto Tinarelli ◽  
Paolo Mazza
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Equivalent Circuit ◽  
High Voltage ◽  
Equivalent Model ◽  
Simulation Environment ◽  
Element Analysis ◽  
Ratio Error ◽  
Complicated Geometries

Stray capacitances (SCs) are a serious issue in high-voltage (HV) applications. Their presence can alter the circuit or the operation of a device, resulting in wrong or even disastrous consequences. To this purpose, in this work, we describe the modeling of SCs in HV capacitive dividers. Such modeling does not rely on finite element analysis or complicated geometries; instead, it starts from an equivalent circuit of a conventional measurement setup described by the standard IEC 61869-11. Once the equivalent model including the SCs is found, closed expressions of the SCs are derived starting from the ratio error definition. Afterwards, they are validated in a simulation environment by implementing various circuit configurations. The results demonstrate the expressions applicability and effectiveness; hence, thanks to their simplicity, they can be implemented by system operators, researchers, and manufacturers avoiding the use of complicated methods and technologies.

scholarly journals Optimised calibration programmes for comparators for instrument transformers

2021 ◽  
Vol 88 (2) ◽  
pp. 122-131
Author(s):  
Christian Mester
Keyword(s):  
Experimental Study ◽  
Operating Principle ◽  
Device Under Test ◽  
Operating Range ◽  
Ratio Error ◽  
Phase Displacement ◽  
Instrument Transformers ◽  
Instrument Transformer ◽  
Method Of Measurement

Abstract Traditionally, instrument transformers are calibrated using bridges. By definition, bridges use the null method of measurement. The traditional calibration programme for instrument transformer bridges characterise namely this null measurement. Many new commercial comparators for instrument transformer use a very different method. They sample the secondary signals of reference and device under test (dut) transformer independently. Based on the samples, magnitude and phase of both signals are determined. Ratio error and phase displacement are calculated. Consequently, the significance of their calibration using the traditional calibration programme is limited. Moreover, the operating range of modern comparators is much larger than that of bridges. The additional versatility cannot be used without an adapted calibration programme. This article analyses the calibration programmes for both technologies. An experimental study confirms both the suitability of the new calibration programme and the need to chose the calibration programme depending on the technology of the device to be calibrated. The conclusion is very general and applies to all measurement problems where an operating principle is replaced by another – when changing the operating principle, it is important to check the calibration programme and adapt it if necessary.

Three-Dimensional Potential and Electric Field Distributions in HV Cable Insulation Containing Multiple Cavities

2013 ◽  
Vol 845 ◽  
pp. 372-377 ◽  
Author(s):  
Nabipour Afrouzi Hadi ◽  
Zulkurnain Abdul-Malek ◽  
Saeed Vahabi Mashak ◽  
A.R. Naderipour
Keyword(s):  
Electrical Properties ◽  
Electric Field ◽  
High Voltage ◽  
Three Dimensional ◽  
The Finite Element Method ◽  
Low Dielectric ◽  
Underground Cable ◽  
Insulation Failure ◽  
Field Distributions ◽  
Hv Cable

Cross-linked polyethylene is widely used as electrical insulation because of its excellent electrical properties such as low dielectric constant, low dielectric loss and also due to its excellent chemical resistance and mechanical flexibility. Nevertheless, the most important reason for failure of high voltage equipment is due to its insulation failure. The electrical properties of an insulator are affected by the presence of cavities within the insulating material, in particular with regard to the electric field and potential distributions. In this paper, the electric field and potential distributions in high voltage cables containing single and multiple cavities are studied. Three different insulating media, namely PE, XLPE, and PVC was modeled. COMSOL software which utilises the finite element method (FEM) was used to carry out the simulation. An 11kV underground cable was modeled in 3D for better observation and analyses of the generated voltage and field distributions. The results show that the electric field is affected by the presence of cavities in the insulation. Furthermore, the field strength and uniformity are also affected by whether cavities are radially or axially aligned, as well as the type of the insulating solid. The effect of insulator type due the presence of cavities was seen most prevalent in PVC followed by PE and then XLPE.

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