This paper deals with the study of static and dynamic rotor eccentricities of a synchronous generator using 3-D FEM. First, both eccentricity cases are introduced, as well as the used approach. Then the models of the structure, based on the magnetic scalar potential formulation and on the magnetic vector potential formulation, are presented. Two eccentricity modeling methods are introduced, the 2-D eccentricity and the 3-D eccentricity. Results obtained for magnetostatic and magnetodynamic cases related to both defects and their combination are presented and discussed.