Affiliations: [a] Laboratoire Systèmes Electrotechniques et Environnement, University Artois, Béthune, France | [b] ThyssenKrupp Electrical Steel UGO, Isbergues, France
Correspondence:
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Corresponding author: Guillaume Parent, Laboratoire des Systèmes Electrotechniques et Environnement (LSEE), University Artois, EA 4025, Béthune, F-62400, France. Tel.: +33 (0)3 21 63 72 44; Fax: +33 (0)3 21 63 72 21; E-mail:[email protected]
Abstract: The most critical areas in power transformers are their corner joints where the magnetic flux distribution presents a very high heterogeneity. This heterogeneity results from several parameters such as the geometry of the magnetic core, the anisotropy level of the electrical steel laminations and a critical induction. This paper is focused on the magnetic steel grades influence on the critical induction, adding a new parameter to those classically considered, such as the number of steps in a multiple step lap stack. Due to the difficulty to perform local measurements inside a real transformer corner, the study is performed both experimentally and by Finite Element analyses on a simplified magnetic core structure. The paper highlights that, in a corner of a core, it exists a critical induction level which depends on the magnetic steel grades and that, in a lamination, the magnetic flux density value along the Transverse Direction can be of the same order that it has along the Rolling Direction.
Keywords: Finite element method, grain oriented electrical steel, magnetic cores, transformers
