Non-linearity of Hysteresis and Eddy Current Losses of Single-phase Distribution Transformers

During transformer modeling, the correct representation is an important stage to achieve a reliable computational simulations. The effects of the ferromagnetic core and its losses need to be considered in the simulations involving low-frequency transients to improve the model accuracy. This paper aims to analyze the non-linearity of hysteresis and eddy current losses to contribute to transformer modeling studies. By applying the two-frequency method, it is possible to separate the hysteresis and eddy-current losses from the no-load losses and evaluate these losses at different frequencies and voltage levels. The formed database contributes to a most reliable calculation of the hysteresis and eddy current resistances in transformer modeling. It is possible to notice a non-linear behavior of both losses and resistance values, with a similar trend between the analyzed samples. Thereby, this paper recommends implementing this nonlinear behavior in computational simulation models, especially in studies related to inrush currents.