Models, Simulations and the Reality of Temperature Rise in Oil-Filled Transformers

We present a description of the heat transfer mechanism in an oil-filled transformer that incorporates two main bottlenecks for the heat flow. The first one, the transfer from its windings into the oil, is simulated using a realistic 3D model and a finite element method. The second, the transfer from the transformer's wall into the environment is described with a robust analytical model. The combination of the two gives an accurate prediction of critical temperatures better than 2 degrees C. The study was done in collaboration with BEZ Transformatory, a.s.