BARROS, R. M. R.; http://lattes.cnpq.br/6066634529532605; BARROS, Rafael Mendonça Rocha.
Resumo:
This work presents a study regarding the contribution of inrush current to the occurrence of
mechanical fatigue in windings of a power transformer and, consequently, the impact of that
phenomenon on the equipment’s lifetime. In order to perform the study, it was used
electromagnetic transient simulations to determine the inrush current in a three-phase
transformer model. Then, simulations, based on the Finite Element Method, were performed to
determine the electromechanical stresses in the equipment windings, under the effect of the
inrush current. Next, the methods of Critical Plans and Palmgren-Miner were applied to perform
the fatigue study. From the simulations results, it was possible to determine the impact of inrush
current on the integrity of the windings of a transformer, as well as, to estimate the lifetime
reduction of the equipment due to inrush occurrence. It was also possible to determine the
number of inrushes needed to estimate the total lifetime reduction of the equipment due to the
mechanical fatigue. The results can also be used in transformers design stage, with the purpose
of assisting the evaluation of mechanical withstand of an equipment, which can minimize the
possibility of failure and increase its lifetime.