SUMMARY
Although, electromechanical transients or transient stability studies are fundamental for the understanding of the dynamical behavior of electrical power systems, this type of studies are usually ignored when dealing with industrial power systems. Analysis of this type of studies is a valuable source of information for determining the need for corrective actions with the aim of improving the overall system’s performance. In this paper, the dynamic behavior of an industrial power system with on-site generation and interconnected with transmission system of the public utility, following the fault ocurrence on the interconnection transformer, is analyzed. The analysis of the study case reported in this paper was fundamental for the undertastanding of the proper operation of the lower- and over-speed protectin devices of the system generators and the total collapse of the industrial system as well.