Analysis And Measurement Of Leakage Magnetic Field In Large-Capacity Transformer

In many large power transformers, large current of coil will cause a very strong leakage magnetic field. A series of additional losses will appear in the various structures of a transformer (oil tank, enclosure, flange and the tank along, etc.). These losses not only account for a large part of load loss in the transformer, but it is unevenly distributed in the metal structure. The loss which concentrated in a small area often causes the considerable local overheating. In order to make the transformer normally run and reasonably be optimized, the in-depth and accurate research on local overheating has the important engineering significance.This paper bases on the overall structure of large-capacity power transformer, and analyzes the three-dimensional model of magnetic field in transformer. ANSOFT software is used for the analysis of leakage magnetic field in transformer to achieve the establishment of finite element model. Through calculating process, the analytical results of leakage magnetic field are obtained on the structure of transformer. And the distribution of local overheating is gotten in each structure from the analytical results, which is the sufficient theoretical basis for the realization of testing method.In order to solve local overheating, this paper finishes the related detection of leakage magnetic field on some structures of transformer. According to the testing principle of electromagnetic induction, measuring magnetic plates are set in the corresponding position. A series of testing results are gotten to compare with the analytical results of ANSOFT software. The errors caused by testing results satisfy the engineering practice. Finally, the advantage and disadvantage of detecting method are summarized. It is very helpful to the optimization of transformer.