ANISOTROPY IN 3-PHASE TRANSFORMER CIRCUIT MODEL

In this paper, an important discussion of transformer design and model ling is given, Afterwards, the anisotropy effects of the transformer l aminations have been stressed in light of the investigation of a three -phase three-limb transformer T-joint, Three simple T-joint modelling schemes accounting for the lamination anisotropy are proposed, The fun damental result is that the flux lines remain almost parallel to the r olling direction (RD), except in a small area around the T-joint. Ther efore, transformer yokes and limbs have been divided into longitudinal elements according to the RD. Reluctances related to these elements a re connected according to the magnetic circuit coupling and yield a ne w transformer circuit model. A good agreement is obtained between comp uted and measured transients currents, Furthermore, the new transforme r model enables some localized analysis, The computed localized fluxes and loci of flux density vectors near to the T-joint exhibit a satisf actory agreement with many results based on FEM or experimental invest igations.