A. Rezic and Z. Valkovic
Calculation of flux distribution in three‐phase three‐limb transformer core has been made using 2D finite element method. The calculation has been performed with and without…
Abstract
Calculation of flux distribution in three‐phase three‐limb transformer core has been made using 2D finite element method. The calculation has been performed with and without taking into account lthe hysteresis of magnetic material. Anisotropy of magnetic material has been modelled through the so‐called elliptic permeability model. Comparison of results of calculation and results of measurement has been performed for a scale model of transformer core. An agreement better than 3 per cent has been obtained, for calculated and measured results of third harmonics and of flux distortion factors, when hysteresis has been taken into account. The CPU‐time was 6–10 times longer when hysteresis has been included into calculation.
Robert Sitar, Žarko Janić and Željko Štih
– The purpose of the paper is to compare losses and temperatures in power transformer tanks for different high current lead arrangements.
Abstract
Purpose
The purpose of the paper is to compare losses and temperatures in power transformer tanks for different high current lead arrangements.
Design/methodology/approach
3D computational tools MagNet and ThermNet based on the finite element method are used to calculate magnetic field distribution in 3D models of power transformers. Eddy current losses in conducting metal parts are induced by the stray magnetic field of transformer windings and high current leads. From loss distribution and appropriate cooling condition temperature values are calculated.
Findings
From calculation results it is possible to understand advantages and disadvantages of different lead arrangements. The analysis is finalized with a short presentation of the influence of magnetic shielding height on temperature and loss values.
Originality/value
Results give transformer designer clearer understanding of precautions that should be taken for avoiding high temperatures on the tank wall of a transformer.
Details
Keywords
Magnetic properties of step‐lap joints have been investigated experimentally on scale‐models of a three‐phase three‐leg transformer core. The influence of core induction, number…
Abstract
Magnetic properties of step‐lap joints have been investigated experimentally on scale‐models of a three‐phase three‐leg transformer core. The influence of core induction, number of steps and overlapping length has been investigated.
Ante Rezic and Zvonomir Valkovic
The influence of overlap length and overlapping design on core loss and magnetizing current of single‐phase two‐leg transformer core has been investigated The investigation was…
Abstract
The influence of overlap length and overlapping design on core loss and magnetizing current of single‐phase two‐leg transformer core has been investigated The investigation was performed experimentally, on scaled models, and numerically, using 2D finite element method Two types of overlapping, mitred and staggered one, were investigated. It has been observed that the influence of overlap length on core magnetic characteristic is much higher in the case of the mitred overlap than that of the staggered one. This difference has been explained by the reduction of core cross section due to the triangle cutout in the mitred overlap.
Oussama-Ali Dabaj, Ronan Corin, Jean-Philippe Lecointe, Cristian Demian and Jonathan Blaszkowski
This paper aims to investigate the impact of combining grain-oriented electrical steel (GOES) grades on specific iron losses and the flux density distribution within a…
Abstract
Purpose
This paper aims to investigate the impact of combining grain-oriented electrical steel (GOES) grades on specific iron losses and the flux density distribution within a single-phase magnetic core.
Design/methodology/approach
This paper presents the results of finite-element method (FEM) simulations investigating the impact of mixing two different GOES grades on losses of a single-phase magnetic core. The authors used different models: a 3D model with a highly detailed geometry including both saturation and anisotropy, as well as a simplified 2D model to save computation time. The behavior of the flux distribution in the mixed magnetic core is analyzed. Finally, the results from the numerical simulations are compared with experimental results.
Findings
The specific iron losses of a mixed magnetic core exhibit a nonlinear decrease with respect to the GOES grade with the lowest losses. Analyzing the magnetic core behavior using 2D and 3D FEM shows that the rolling direction of the GOES grades plays a critical role on the nonlinearity variation of the specific losses.
Originality/value
The novelty of this research lies in achieving an optimum trade-off between the manufacturing cost and the core efficiency by combining conventional and high-performance GOES grade in a single-phase magnetic core.
Details
Keywords
Erich Schmidt, Peter Hamberger and Walter Seitlinger
To maintain quality, performance and competitiveness, the eddy current losses in metal parts of power transformers in the range of 50‐200 MVA are investigated in a more detailed…
Abstract
To maintain quality, performance and competitiveness, the eddy current losses in metal parts of power transformers in the range of 50‐200 MVA are investigated in a more detailed form. The finite element calculations utilize different modelling strategies for the current carrying metal parts. Several global and local results are further used to obtain simplified calculation approaches for an inclusion in the initial design and the design optimization. The results from two finite element approaches using nodal and edge based formulations will be compared with measurements.