The paper deals with the determination of synchronous machine parameters using a 2D Finite Element Method – FEM (Flux2D- Cedrat). Simulations of no-load sudden three phase short- circuits are performed in rotation, the saturation effects and the eddy currents in the rotor solid iron parts are also taken into account. Comparisons between calculations and measurements for two large existing units (turbogenerator & hydrogenerator) are presented.