Sharif University of Technology Scientia Iranica 1026-3098 16 2 2009 12 01 Estimation of Hottest Spot Temperature in Power Transformer Windings with NDOF and DOF Cooling 3281 EN M. A. Taghikhani Department of Electrical Engineering,Iran University of Science and Technology A. Gholami Department of Electrical Engineering,Iran University of Science and Technology Journal Article 2010 05 12 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 (HST) value. The classical approach has been established to consider the hot-spot temperature as the sum of the ambient temperature, the top-oil temperature rise in the tank, and the hotspot- to-top-oil (in tank) temperature gradient. In this paper, the heat conduction equation for temperature is solved. For numerical solution of the heat conduction equation, the nite element method is used. The selected model for simulation is a 32MVA transformer with Non-Directed Oil-Forced (NDOF) cooling and Directed Oil-Forced (DOF) cooling. https://scientiairanica.sharif.edu/article_3281_892fbe80d81ebe8a3c82b5f7218dd3ba.pdf