Characterization of induced surges impulses and their generation in laboratory

Lightning surges are one of the main causes of failures in transmission lines and equipments. Power equipments are usually designed to withstand voltages related to direct lightning strikes, but, for distribution lines, usually there is a natural shielding against direct strikes due to nearby tall structures. In this case, induced overvoltages caused by lightning strikes in the proximities of the line are more frequent and can be a preponderant aspect for the line design. This paper presents a study for the characterization (peak values, front and tail time) of induced surges, generation and evaluation of their effects on 13.8 kV equipments. This characterization is made considering a massive set of induced overvoltages obtained by means of stochastic methods, electromagnetic coupling simulations and statistical analysis. The results were used to design components for the impulse generator of Federal University of Itajubá, so that the induced surges could be generated for equipment testing.