Core lamination selection for distribution transformers based on sensitivity analysis

In this paper, the sensitivity analysis is used to select the core lamination thickness of single-phase distribution transformers rated from 5 to 50 kVA. Three different magnetic materials (M2, M3 and M4) with thicknesses of 0.18, 0.23 and 0.27 mm are considered. Transformer designs are compared based on the total owning cost as well as on the transformer bid price. The impact of the different laminations on total owning cost and bid price is calculated for a total of 144 transformers (72 for each criterion). All transformers fulfill all the operating and construction constraints. The paper considers the impact on core losses of the space factor (core-assembling pressure) and of the building factor and also describes how core losses are affected by core design parameters such as the number of laminations per step, air gap and overlap. It is concluded that for the analyzed power range, M3 lamination is the best choice since all of the studied cases have smaller bid price and 79% of the studied cases have lower total owning cost. This paper gives guidelines to select the appropriate thickness and can help transformer manufacturers to select the optimal thickness for distribution transformers.

[1]  G. Bertotti.  General properties of power losses in soft ferromagnetic materials , 1988 .

[2]  J. Benford,et al.  Separation of losses in oriented silicon steels from 0.13 to 0.34 mm thick , 1984 .

[3]  J. Barranger.  Hysteresis and eddy-current losses of a transformer lamination viewed as an application of the Poynting theorem , 1965 .

[4]  Pavlos S. Georgilakis.  Spotlight on Modern Transformer Design , 2009 .

[5]  Pavlos S. Georgilakis,et al.  Optimal design of single-phase shell-type distribution transformers based on a multiple design method validated by measurements , 2011 .

[6]  Martin F. Littmann.  Properties of grain oriented 3% silicon steel for transformers with minimum cost of ownership , 1982 .

[7]  J. Pedra,et al.  Three-phase transformer modelling for unbalanced conditions, Part 1: core modelling and introductory examples , 2008 .

[8]  Barry W. Kennedy.  Energy Efficient Transformers , 1997 .

[9]  Johan Driesen,et al.  Impact of the joint design parameters on transformer losses , 2003 .

[10]  A. J. Moses,et al.  Electrical steels : past, present and future developments , 1990 .

[11]  P. Marketos,et al.  Generalization of the Classical Method for Calculating Dynamic Hysteresis Loops in Grain-Oriented Electrical Steels , 2008, IEEE Transactions on Magnetics.

[12]  W. S. Mota,et al.  Magnetic core model , 2007 .

[13]  R. Simoneau,et al.  Development and application of amorphous core-distribution transformers in Québec , 1995 .

[14]  A. Kladas,et al.  Multiple Grade Lamination Wound Core: A Novel Technique for Transformer Iron Loss Minimization Using Simulated Annealing With Restarts and an Anisotropy Model , 2008, IEEE Transactions on Magnetics.

[15]  C. M. Arturi,et al.  Static and Dynamic Hysteresis Models for Studying Transformer Transients , 2011, IEEE Transactions on Power Delivery.

[16]  M. Littmann,et al.  Iron and silicon-iron alloys , 1971 .

[17]  V. R. V. Ramanan,et al.  Metallic glasses in distribution transformer applications: An update , 1991 .

[18]  László Kiss,et al.  Large Power Transformers , 1987 .

[19]  J. Thompson,et al.  A review of some interdisciplinary work on grain-oriented silicon-iron and its use in large power transformers , 1967 .

[20]  F. Rivas-Dávalos,et al.  A NEW METHOD TO EVALUATE MEAN LIFE OF POWER SYSTEM EQUIPMENT , 2009 .

[21]  岡崎 靖雄,et al.  Soft Magnetic Materials 14 (SMM 14) 会議報告 , 2000 .

[22]  S. D. Probert,et al.  Effect of thermal contact resistance on the performance of transformer lamination stacks , 1977 .

[23]  R. H. Pry,et al.  Calculation of the Energy Loss in Magnetic Sheet Materials Using a Domain Model , 1958 .

[24]  Anthony John Moses,et al.  Comparison of engineering methods of loss prediction in thin ferromagnetic laminations , 2008 .