Electrical modeling of transformer connecting bars

Traditionally, connections in high-voltage, high-current, and low-frequency circuits are always considered as perfect short circuits, so to analyze their contribution to electrical performance of a structure is not considered necessary. We show here that, even for low-frequency structures, the electrical parasitic characteristics of cabling can lead to some unexpected performances. In particular, our study of outside connections of a 400 MVA transformer has shown current imbalances between the three phases and inside the phases. We achieved this by using a semianalytical method that is presented in this paper. Results show the need to model this part of the structure. This method has advantages over numerical techniques of calculation.