In the actual operation of bulb continuous unit

the rotor-runner system is easy to form friction fault between rotating parts and fixed parts allected by extermal incentives

which greatly affects the safe and stable operation of unit. Aimed at the problem of axial friction with fault receptor components

the unbalanced magnetic tension model under rotor composite eccentricity is conshructed

the vibration model of rotor-runner coupled bending torsional vibration with the excitation of multi-source

and its diferential motion equation are established. The dierence of vibration characteristics for converter system is studied and the nonlinear vibration characteristics of system in excitation curent

rotor and runner mass eccenticity are discussed. The results show that failure inereases the unsteady motion range of rotor and runner

causing the system to produce adverse vibration and occasion malfunetion. Meanwhile

the rotor under the same operating conditions and parameters shows a greater amplitude strength than the runmer

which should be more attention. With considering the torsional degrees of freedom

the rotor amplitude amplifies under mass eccentricity variations

resulting in the rub-impact malfunction. In addition

when the runner mass eccentricity is developed to a certain extent

the uncertain random hydraulic force at the blade will induce instability of system. The results can provide useful references for safe operation and stability analysis of bulb tubular unit.