Abstract: The shafting stability was introduced aiming at 1000MW ultra-supercritical turbine-generator set of Zouxian power plant phase IV. The results calculated in design, which included instability speed, specific pressure, and logarithm damping ratio of bearing, the lateral vibration and torsional vibration properties of shafting, were analyzed. The shafting stability was judged by adopting Q factor method. The causes of steam flow excited vibration and its design criterions as well as preventing measures were expounded. The operating status after putting the measures in practice was described briefly, and the basic stability criterions of turbine shafting used by main manufacturers abroad were recommended.

Key words: Stability of shafting, critical speed, Q factor, logarithm damping ratio, steam flow excited vibration