Epstein frame: how and when it can be really representative about the magnetic behavior of laminated magnetic steels

In this paper, using suitable three-dimensional finite element method (FEM) approaches, either in frequency or in time domain, we will analyze the real magnetic behavior of a commercial Epstein machine, prescribed as standard magnetic measurement system. The analysis of magnetic field and eddy currents explains some facts that can affect the accuracy of Epstein frames as measuring systems for the magnetic characterization of laminated Si-Fe steels. The same FEM approaches shall be applied here to outline and define quantitatively some advantages in accuracy can be obtained using single sheet testers instead of Epstein frames.