Overvoltage Produced by Lightning Impulse in High Power Transformers - Parameters that Influence their Transmission

The overvoltages caused by the lightning impulse, at the level of the high power transformer, have a great importance from the design stage. For these reasons, this paper presents the electrical parameters that influence the transmission of overvoltages in the transformer windings, but also a method for determining them. To simulate the phenomenon caused by lightning impulse on the transformer, an application was realized in the LabVIEW development environment. This application allows to determine the values of the transmitted overvoltages between the transformer windings. The study was performed on a transformer of 54/73 MVA, TTUS-ONAN, 110/15 / 6.6 kV, and the results obtained were validated by laboratory tests.