Modified Epstein frame for measuring electrical steel under transformer like conditions

In this paper a modified Epstein frame which delivers measurements under transformer like conditions is proposed. The steel sheet samples are stacked according to the method applied in real power transformer cores with similar geometrical conditions. Another parameter which should be investigated with the modified Epstein frame is pressure. In a transformer core the stacked steel sheets are pressed by bandaging to stabilize the core. This pressure has an influence on the magnetic characteristics of the used electrical steel. The new measuring device is designed with a FEM-Software to compare magnetic field distribution with the Epstein frame. The modified Epstein frame is built according to the FEM results and construction requirements as a matter of the pressure armature. Finally measurements of Epstein frame, Single sheet tester and modified Epstein frame all equipped with the same electrical steel are compared.