Hottest Spot and Life Evaluation of Power Transformer Design Using Finite Element Method

Power transformers represent the largest portion of capital investment in transmission and distribution substations. In addition, power transformer outages have a considerable economic impact on the operation of an electrical network. One of the most important parameters’ governing a transformer’s life expectancy is the hot-spot temperature value. Due to under estimation of stray losses in power transformer hot spots are formed. So the stray loss evaluation is an essential aspect to calculate hot spot temperature. The stray losses in transformer is caused by the time variable leakage flux which induces emf’s & circulates eddy currents in the winding conductors and other conducting parts of transformer like tank wall, core, clamps etc.. Evaluation of stray losses can be done more accurately by Finite Element Method (FEM). This paper presents the new and more accurate temperature calculation methods taking into account the above mentioned findings to estimate life of transformer form hot spot temperature.