通过振动监测诊断发电机转子裂纹

直接确定裂纹的方法仅能够在停机条件下检测。振动监测在运行状态下进行,对诊断裂纹尤为重要。介绍通过振动监测对一台发电机转子裂纹进行诊断的事例。该发电机主要振动特征为：转子的振动和晃度经常增大,需要经常进行平衡,而且平衡的方向接近；并网后振动随负荷增大,增大表现有时为渐变的,有时为突变的；到一定阶段后,振动失去再现性,即便进行平衡调整也不起作用。依据裂纹转子振动的机理,判断转子可能存在裂纹,经检查发现表面裂纹的长度已经超过圆周的80%。由于判断准确检查及时,避免了一场重大事故的发生。

Diagnosis of crack on the generator rotor by means of vibration monitoring

Directly detecting of the cracks on generator rotor can be available only in case of shutdown.Since the vibration monitoring system works during the operation of turbogenerator unit,it is important for the cracks detecting.The diagnosis case for cracks on certain generator rotor was introduced.The main vibration eharacteristies for this case are as below:the vibration and shake increase frequently, requiring for the balancing from time to time,and the balancing directions are in nearby position;the vibration becomes even greater, presenting as gradual or sudden change after the synchronization;in certain stage,the vibration loses emersion characteristics even if the balancing adjustment is made.Based on the vibration mechanism of the cracked rotor,cracking problem can be confirmed on the generator rotor.It is verified by the inspection result that the length of cracks has already exceeded 80% of the circumference.Thus,an accident was avoided with right judgment in time.