This paper describes a detailed circuit representation of synchronous machines equipped with two similar or dissimilar armature windings. The equivalent circuit at steady state is presented. The self and mutual leakage inductances of the two sets of three-phase stator windings are evaluated by the finite element method as well as an analytical method. The simulation results from a steady-state analysis as well as a fault analysis are verified experimentally on the world's first high-voltage generator Power-former installed in Porjus, Sweden, rated at 45 kV and 11 MVA.