Magnetostriction force spectrum in power transformer

Witczak, Pawel

doi:10.1109/icelmach.2014.6960497

Cited by 4 publications

(3 citation statements)

References 10 publications

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“…Hsu et al [15] propose a new method to reduce the transformer core noise by re-arranging the step-lapped joint structure. Efforts are made to study the correlation of magnetostriction variation [16], DC bias [17], magnetostriction force spectrum [18], harmonic voltages [19], climbings [20] and magnetic hysteresis [21] on power transformer noise emission.…”

Section: State Of the Artmentioning

confidence: 99%

Reduction of Power Transformer Core Noise Generation Due to Magnetostriction-Induced Deformations Using Fully Coupled Finite-Element Modeling Optimization Procedures

et al. 2017

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This work focuses on the development of an algorithm for the prediction of transformer core deformation, using a fully coupled magneto-mechanical approach. An imposed magnetic flux method coupled with finite element modeling is employed for the magnetic resolution. The constitutive law of the material is considered with a simplified multi-scale model (SMSM) describing both magnetic and magnetostrictive anisotropies. Magnetostriction is introduced as an input free strain of a mechanical problem to get the deformation and displacement fields. A 3D estimation of acoustic power is carried out to evaluate the global core deformation and acoustic noise level. The numerical process is applied to a three-phase transformer made of Grain Oriented (GO) FeSi core, leading to a set of noise estimation for different flux excitations and core geometries.

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Section: State Of the Artmentioning

confidence: 99%

Reduction of Power Transformer Core Noise Generation Due to Magnetostriction-Induced Deformations Using Fully Coupled Finite-Element Modeling Optimization Procedures

et al. 2017

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“…The stress originated from the magnetic field distribution may have two forms – magnetostatic stress: where H i and B k are magnetic field and flux density components and w′ is magnetic co-energy density, and magnetostriction stress (Witczak, 2014): where G is shear modulus and ε denotes strain. The form of (4) means that magnetostriction deformations preserve the constant volume.…”

Section: Basics Of Magnetostatic and Magnetostriction Forcesmentioning

confidence: 99%

“…For this reason, it is much more convenient to restrict initially the possible deformation to basic two forms described by Döring-Becker equation (Becker and Döring, 1939) and look for magnitudes of these forms. It is possible to show (Witczak, 2014) that magnetostriction stress tensor τ ik at a given point where the flux density is described by magnitude B and angle α against rolling direction amounts to: where λ 1 and λ 2 are elongation functions of B 2 measured for magnetization along and transversely to the rolling direction. The values of these coefficients differ significantly; they are in a range λ 2 /λ 1 =(20÷40).…”

Section: Basics Of Magnetostatic and Magnetostriction Forcesmentioning

confidence: 99%

Magnetic forces applied to the tank walls of a large power transformer

Witczak

Świątkowski²

2016

COMPEL

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Purpose The purpose of this paper is to calculate forces created by the magnetic leakage field, which are directly applied to tank walls via magnetic shield. Design/methodology/approach Electromagnetic and mechanical calculations use 3D finite element technology, both applied to materials having constant orthotropic properties. The magnetic solver uses harmonic excitation; the analysis of mechanical deflection is carried out in static conditions. Two types of forces are considered: magnetostatic surface forces and magnetostriction volumetric ones. In measurements, the laser scanning vibrometer was applied. Findings Electromagnetic calculations must use an FE mesh much denser than that for typical power loss analysis. The magnetic orthotropy of the shield material does not create any important effects and it may be omitted. Magnetostriction forces are similar in value to magnetostatic ones, but their influence on the shield deformation is negligible. Research limitations/implications The results obtained for the analysis of the displacement of elements of the tank wall are exemplary – they show the difference between magnetostatic and magnetostriction excitation only. The analysis of the vibration of the transformer tank must include the presence of the oil inside the tank. Originality/value The asymmetrical placement of magnetic shields against the transformer core creates the visible differences in the magnitudes of magnetostatic forces applied to particular shields. Therefore, the design of magnetic shielding should also include the vibrational point of view.

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A new approach of core structure model for 3-phase distribution transformer

Alyozbaky

Kadir

Izadi

et al. 2018

Int Trans Electr Energ Syst

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Summary Reducing the losses of 3‐phase transformers is still considered a significant target by many transformer designers and manufacturers. Core joint design is one of the factors related to the losses. In previous studies, core losses and flux density distribution motivated researchers to design appropriate T‐joints. However, the variation of load and thermal profiles are the most important factors related to the losses in transformers. This study proposed a new T‐joint configuration for the core of the 3‐phase transformer. The proposed model was built after considering the variation of load and thermal profiles. Results were compared with those of conventional T‐joint designs, such as butt‐lap and 45° mitered designs, that are currently used. The no‐load losses of the proposed model were reduced by more than 6.8% and 10% compared with those of the butt‐lap and mitered T‐joint designs, respectively. Furthermore, the total losses, the hot spot temperature of the core, and the oil temperature decreased significantly. The proposed model contributes to the literature on new T‐joint designs for improving transformer performance.

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Magnetostriction force spectrum in power transformer

Cited by 4 publications

References 10 publications

Reduction of Power Transformer Core Noise Generation Due to Magnetostriction-Induced Deformations Using Fully Coupled Finite-Element Modeling Optimization Procedures

Reduction of Power Transformer Core Noise Generation Due to Magnetostriction-Induced Deformations Using Fully Coupled Finite-Element Modeling Optimization Procedures

Magnetic forces applied to the tank walls of a large power transformer

A new approach of core structure model for 3-phase distribution transformer

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