Feasibility of Site Balancing Rewinded 2-Pole Turbo Generators Available to Purchase

At power plants with large distances to workshops and balancing facilities the outage time for rewinding of a generator rotor may be considerably reduced if the work can be carried out on site. However a problem arises when balancing is concerned. If the rotor is balanced on site, i.e. in the stator and driven by the turbine, the balancing weights at the rotor body are not accessible. This constraint and the critical speeds of the rotor determine the feasibility to achieve an acceptable balancing state. This paper first presents estimates of the expected unbalance introduced by rewinding based on the balancing weight distribution for a set of rewinded rotors. These estimates are then applied to a rotordynamical model and a search algorithm is used to see what can be achieved by balancing in the accessible balancing planes. Several numerical examples are studied. Finally, some guidelines for feasibility of site balancing rewinded turbo generator rotors are defined based on the numerical results.