Numerical determination of characteristic temperatures in directly loaded power oil transformer

The paper presents the application results of original non‐linear non‐stationary thermal model of the oil power transformers. The main advantage of the model is precise treatment of non‐linear convection heat transfer influence to the transient thermal process. It is convenient to calculate the model parameters from the short‐circuit heating experiment. The aim of this paper is to investigate the precision of such obtained parameters application to a transformer in normal operation. For that purpose, the precise calculation of power losses distribution is needed and is proposed in the paper. For experimental verification of the model accuracy the measuring method for continuous monitoring of mean winding temperature of directly loaded transformer is developed.