Serious intermittent vibration occurred on No.2and No.3tile of four subcritical 330 MW unit turbines in a power plant

after several months' stable operation.Thus

investigation on the same type units was conducted.Carbide frictional vibration caused by carbon deposition on oil baffle was considered as the major reason.By regulating micro negative pressure of the lubrication oil tank and performing retrofitting on the airtight oil gear

the large vibration problem was successfully overcome.The vibration amplitude of the No.2tile stabled at 65μm

and the fluctuation of the No.1tile reduced to 10μm

indicating the unit vibration return normal.