An investigation of parameters affecting the temperature rise in windings with zigzag cooling flow path

Disk type windings are widely used in large power transformers. Block washers are used within some designs of this winding type to help to direct the oil flow. These washers increase the heat transfer coefficient, decrease hot spot temperature and consequently make the transformer smaller. A proper model is helpful to calculate the temperature distribution inside a natural convective cooled disk type winding including block washers. Therefore, in this paper a mathematical thermal model is presented and its validity and accuracy is verified with experimental measured data. Meanwhile, the effects of some parameters such as heat loss, number of washers, height of radiators and channel geometry are investigated using the model.