The loading of rotating electrical machines (generators) are of versatile nature and are generated by magnetic and mechanical forces. The strength behaviour of the single components is determined by the appearance of elastic-plastic cyclic deformation at different, sometimes partially local, areas. If these local high stresses exceed the yield strength or ultimate strength of the involved material damages of different extent will appear. Damages of bulb-type generators of the Austrian Danube water power plant “Altenwörth” were the motivation for investigations to study the low cycle fatigue behaviour of welded components. Due to the damages detected high interest was focused on the influence of superposed cycles. The influence of superposed cycles on decreasing life time was proved on fatigue tests of non-welded and butt welded specimens as well as on fillet welded specimens. The comparison of the own test results with data of specifications, regulations and calculation programs showed that these specifications, regulations and calculation programs apply to specific products. Therefore the limiting values do not apply for a general technical and economical dimensioning. As a consequence of these not satisfactory results continuing investigations will be conducted in co-operation with the Materials Centre Leoben to determine exact design data for highly stressed components of generators.