The effects of pole number and rotor wedge design on unbalanced magnetic pull of the synchronous generator

In the paper, the effects of magnetic saturation and damper winding currents on the unbalanced magnetic pull of synchronous generator were analyzed by using the Finite Element Method calculations. Analyses were conducted for no load and rated load conditions on two types of generators. Firstly on the 40-pole, 10.5 MVA, salient pole synchronous generator and then on 2-pole, 40 MVA turbo generator. From the results it can be seen that magnetic saturation and damper winding currents decrease the force of unbalanced magnetic pull. In no load condition, for voltage level lower than the rated value, the maximal value of this force is achieved. In case of 2-pole generator, magnetic saturation has smaller effect on the force of unbalanced magnetic pull, than on the damper winding currents. The use of magnetic wedges on rotor can cause superposition of alternating component to the static component of the unbalanced magnetic pull.