Analysis On Eddy Current Loss And Thermal Field In Winding Of Dry Type Transformer

Dry type transformer is used more and more widely, by it has characteristicsthat simple structure, non-toxic, flame retardant, not detonation, so it is verysuitable for urban construction, shopping sites and many other public places.With the increase of the single transformer’s capacity, loss will be graduallyincrease, the transformer thermal problems is significant outstanding.Transformer winding overheating not only cause insulation of accelerated agingand affect its life, but also by the coil local overheating can cause seriousaccident. Therefore, accurate calculation dry type transformer of the eddy currentloss and temperature field will play an very important role in dry typetransformer design.This paper based on fundamentals of electromagnetic theory, as an exampleof non-encapsulated dry type transformer, and by using ANSYS finite elementsoftware “field-circuit coupled method” is established, establish two-dimensionalsolution mode accord to the actual transformer winding structure, throughcalculation and analysis, getting the distribution of leakage magnetic in theinternal of dry type transformer, and analysis the distribution of radial and axialmagnetic flux leakage at the inside and outside of the high-low winding.By using finite element method, the two different winding form of high andlow voltage winding on the eddy current loss analysis, analysis of the eddycurrent for the influence of the current density in the winding, and then analyzesthe eddy current loss for influence of loss distribution, and through comparisonthe2D and3D, then analysis the foil type winding in the loss of the eddycurrent distribution characteristics. The eddy current loss calculation formula isderived, using the result of leakage magnetic field calculation, calculate each unitof the eddy current loss, and made the analysis to the winding of the eddy currentloss value and distribution.After calculation the winding of the eddy current loss distribution, calculate the part of the total loss, according to the related theories about heat transfer andfluid mechanics, in view of the characteristics of the non-encapsulated dry typetransformer established two dimensional temperature field analysis model, eachunit loss calculation results as a heat source is applied to temperature fieldcalculation model, and uses the fluid-solid coupling method, to the analysis fieldof transformer model on the flow field and temperature field coupling analysis;Again to all kinds of load respectively under the temperature field analysis,getting the characteristics of hot temperature rise and position distribution,Putting forward to improve the hot place fan temperature method, this paperanalyzes the different wind speed for the influence of the temperature of hotspots.