Error estimation of current transformers using single or composite cores of ferromagnetic materials
TL;DR: In this article, a computer program which has been developed to estimate the errors of current transformers using single or composite cores of ferromagnetic material is discussed, which enables determination of the permeability and resolved excitation characteristics of a composite core formed utilizing N independent cores of M different materials.
Abstract: A computer program which has been developed to estimate the errors of current transformers using single or composite cores of ferromagnetic material is discussed. The program enables determination of the permeability and resolved excitation characteristics of a composite core formed utilizing N independent cores of M different materials. >
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20 Dec 2004
TL;DR: In this paper, a virtual instrument that can be used for performance measurements of instrument transformers (IT) in addition to analyzing the magnetic characteristics of cores is proposed, and experimental results are shown to validate the proposed method.
Abstract: Current transformers (CT) and voltage transformers (VT) are the primary sensing elements in electric power systems. While their performance at a single frequency is well known, it is necessary to analyze the performance of CTs and VTs for harmonic excitation. A single virtual instrument that can be used for performance measurements of instrument transformers (IT) in addition to analyzing the magnetic characteristics of cores is proposed. Experimental results are shown to validate the proposed method.
14 citations
TL;DR: In this paper, a model for the computation of core losses and excitation current, in a lamination by lamination method, for wound core distribution transformers was developed based on the finite-element method (FEM).
Abstract: SUMMARY
This paper proposes a model for the computation of core losses and excitation current, in a lamination by lamination method, for wound core distribution transformers. The model was developed based on the finite-element method (FEM). The results obtained by applying the proposed model were compared with the FEM results and with the measurements of the no-load test. The no-load losses obtained by the proposed model present a difference of 4% with respect to measured values, while they are almost the same with respect to FEM. The proposed model contributes in the research of new techniques that improve transformer design. Copyright © 2012 John Wiley & Sons, Ltd.
11 citations
01 Nov 2017
TL;DR: In this paper, an electromagnetic finite element (FE) analysis of combinations of electrical steels in the lamination core steps of a real 6.3 MVA single-phase distribution transformer is presented.
Abstract: This paper presents an electromagnetic finite element (FE) analysis of combinations of electrical steels in the lamination core steps of a real 6.3 MVA single-phase distribution transformer. The magnetic core of this transformer has a cruciform cross-section with lamination core steps. Two electrical steels are combined in the lamination core steps of transformer: a convectional grain oriented electrical steel (M-5) and laser-scribed electrical steel (23ZDKH90). 3-D FE simulations are performed to calculate the core losses (no-load losses) without and with combinations of electrical steels. B-H curves and iron loss curves of electrical steels are taken into account in the numerical simulations. The core loss calculated in FE simulation without combination of steels is compared with the core loss measured in no-load laboratory tests. Numerical results show that the combination of electrical steels in the lamination core steps can reduce 5% the core losses in single-phase distribution transformers with stacked magnetic cores. Finally, material costs are estimated for the steel combinations in the magnetic core of transformer.
9 citations
Cites background from "Error estimation of current transfo..."
...Other authors have combined GOESs and nongrain oriented electrical steels (NGOESs) in instrument transformers, and other authors have combined GOESs and some high permeability alloys in toroidal magnetic cores for current transformers to reduce material costs and to improve their measurement properties [11]-[15]....
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31 Aug 2012
TL;DR: In this paper, the authors present an analysis of the bibliography on transformers covering the period from 1990 to 2000, which contains all the transformer subjects: transformer design, transformer protection, transformer connections, transformer diagnostics, transformer failures, transformer modeling and analysis.
Abstract: This paper presents an analysis of the bibliography on transformers covering the period from 1990 to 2000. It contains all the transformer subjects: a) Transformer design, b) Transformer protection, c) Transformer connections, d) Transformer diagnostics, e) Transformer failures, f) Transient analysis of transformers (overvoltages, overcurrents), g) Modeling and analysis of transformer using FEM (thermal modeling, losses modeling, insulation modeling, windings modeling). Several international journals were investigated including the following: Advances in Electrical and Computer Engineering, Canadian Journal of Electrical and Computer Engineering, COMPEL (The International Journal for Computation and Mathematics in Electrical and Electronic Engineering), Electrical Engineering, Electric Power Components and Systems, Electric Power Systems Research, European Transactions on Electrical Power, IEEE Transactions on Magnetics, IEEE Transactions on Power Delivery, International Journal of Electrical Power and Energy Systems, and IET Generation Transmission & Distribution. Due to the high number of publication in journals, we are not considering publications of conferences and symposia. A total of 700 publications are analyzed in this paper. The research presented in this paper is important because it contains and analyzes the best research papers on transformers coming from many countries all over the world and published in top rated scientific electrical engineering journals.
8 citations
01 Jan 2003
TL;DR: The magnetic moment of an electron is 9.27 × 10−24 A.m2 as mentioned in this paper, or 1 Bohr magneton (β), where β is the number of electrons in an electron's magnetic field.
Abstract: An electron is associated with a spin, which results in a magnetic moment. The magnetic moment of an electron is 9.27 × 10−24 A.m2, or 1 Bohr magneton (β). A filled orbital contains two electrons of opposite spin, so the net magnetic moment of a filled orbital is zero.
3 citations
References
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01 May 1956
55 citations
TL;DR: In this article, the magnetic permeability of iron materials (permalloy, high oriented electrical sheets, and thin electrical sheets) and magnetic glasses (Fe-based, Co-based and Ni-based) is investigated.
Abstract: The magnetic permeability of iron materials (permalloy, high oriented electrical sheets, and thin electrical sheets) and magnetic glasses (Fe-based, Co-based, and Ni-based) is investigated. The measurement results concern the composite magnetic circuits, which have a structure comprised of a crystalline material between two layers of amorphous ribbon. The current-voltage characteristics are presented. >
6 citations