Eddy-currents modelling in transformers magnetic cores using ohmic resistances

The inclusion of eddy-currents effects in transformers cores is a very hot subject on transformers modeling. The dominated modeling approach is based on the usage of equivalent ohmic resistances placed in the equivalent electrical circuit which represents the electrical part of the transformer. In this paper, a comparison study, between the main different models using ohmic resistances for the eddy-currents in transformers magnetic cores, is conducted. Specifically, the selection of the suitable ohmic resistance, according to the study that is going to be conducted using an appropriate transformer model, is clarified; a topic that has not sufficiently been investigated and presented in the literature. The methods for determination of the ohmic resistances, in the simple case of a single-phase core-type transformer, are presented. Corresponding numerical results are given, which are compared to measured values if possible.