Aiming at the shafting vibration problem occurred during the valve tightness test of a 330MW steam turbine unit after overhaul,according to the vibration trend and bearing temperature during impulse starting,based on the characteristics of the vibration fault,it is judged that the vibration fault of the exciter rotor is caused by a variety of reasons,such as small damping of the bearing system,low bearing elevation,extension section effect,and long residence time in the critical area.The high vibration of HP and IP rotor is caused by the rub impact between the rotor and the stator.And the treatment plan of raising #7 bearing and closely observing the vibration trend of #1 and #2 bearing is given.Subsequently,the turbine successfully completed all kinds of tests with full load.Vibration fault analysis process and treatment effect show that the bearing elevation directly affects its working state;the exciter rotor belongs to the extension section of the generator rotor.When the bearing support stiffness is insufficient and the binding force on the rotor is small,it may become a cantilever beam model,which is prone to produce unstable vibration;the greater the damping of the bearing system,the shorter the residence time in the critical region,and the smaller the vibration value of the rotors critical speed;the vibration characteristics caused by dynamic and static rub impact of different types and degrees are different.When the vibration divergence caused by rub impact is uncontrollable,the speed must be reduced or the turning gear must be stopped in time.
exciter rotorbearing elevationsystem dampingelongation effectdynamic and static frictionvibration
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