Abstract: In the procedure of No.1 unit debugging of Hunan Huadian Shimen Power Plant, when the load increased to 270 MW, the tripping machine occurred twice due to vibration of low pressure impeller shaft and bearing increased over the protection setting. According to the analysis of the vibration characteristics and the operation parameters, it is decided that the vibration is caused by unstable oil film of No.3 bearing of low pressure impeller. The level of No.3 bearing was adjusted. The top gap of No.3 bush was reduced. The low bush of No.3 bearing was center adjusted. Then the low frequency vibration was eliminated at full load, and all shafts and bearings were stable at fine range.

Key words: unit debugging, low frequency vibration, sudden, analysis, handling