某9FA燃气蒸汽联合循环机组的90 MW汽轮机启动过程中出现异常共振峰，导致机组无法冲转至额定转速。通过对振动数据的变化趋势、频谱特征及分频相位差的分析，否定了共振峰来自转子过临界，排除了轴承座结构共振、基础共振等原因，最后判断原因为涡流传感器支架发生共振。在对支架进行加固处理后，振动值恢复正常，避免了盲目采用动平衡手段降低振动的错误方法，介绍的支架共振特征和故障分析方法可为同类故障的分析诊断提供参考。%An unusual formant occurred in startup of 90 MW steam turbine of 9FA steam-gas combined cycle units, due to which units can not run up to the rated speed. By analyzing trend of vibration data change, spectrum characteristics and frequency phase angel difference, it is denied that the formant is from the over-critical rotor, and bearing pedestal resonance, foundation resonance other reasons are excluded. It is recog-nized finally that the fault is caused by the bracket resonance of the eddy current sensor. The vibration re-turned to normal by reinforcement of the bracket, therefore blind balancing treatment is avoided. Bracket res-onance characteristics and fault analysis method discussed in the paper can provide a reference for analysis and diagnosis of the similar faults.
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