The influence of multidirectional leakage flux on transformer core losses

Abstract In a power transformer, the leakage flux enters the laminations of the iron core in different directions. Depending on the orientation of the leakage flux, it can add eddy current and hysteresis losses to the well-documented losses caused by the main flux. To study the principles of the influence of the leakage flux on the losses in transformer cores, the problem was isolated to an experiment on a stack of laminations in an Epstein-like frame. The frame carried the main flux, while artificial leakage flux is created and forced to enter the laminations in the two directions perpendicular to the main flux. Additionally, the system was modelled using finite elements to interpret the physical phenomena. The results revealed that the loading conditions have a significant impact on the local eddy current loss and on the overall power loss. The identified additional magnetic losses show that under inductive loading, conventional no-load tests can underestimate the core losses considerably.