Based on intermittent vibration phenomenon occurred on high-and medium-pressure rotors in operation of four steam turbines for three kinds

it is believed from analysis that the main cause is accumulation of lubricating oil's carbides at the bearing oil retainer of high-and medium-pressure rotors in steam turbines

impacting and rubbing with the rotor shaft to produce rubbing vibration

being simply called as rubbing vibration due to oil carbonization.In the event the carbides from abrassed part of teeth higher than the oil retainer making the rotary shaft to lose contact with impact-rubbing

the vibration of rotor returns gradually to normal

and then producing newly accumulated carbides to a certain degree

the rotor starts again to occur rubbing vibration.After a certain time

the rotor vibration returns again to normal

thus going around and begining again

cycles are formulated.This abnormal phenomenon is easy to occur on bearings of high-and medium-pressure rotors in large-capacity turbo-generator set with separated high-and medium-pressure cyclinders.