Vibration Monitoring System Integrity Subtly Affects Vibration Symptoms and Impacts Machinery Malfunction Diagnosis

Proper installation and functionality of a rotating machinery protection and monitoring system is essential for accurate diagnosis of machinery related malfunctions. For some gas turbine driven generator units, some monitoring system components can be internal to the machine and somewhat inaccessible. Monitoring system component problems and failures can result in obvious symptoms; however in a few instances these symptoms can be subtle and lead to a false or inappropriate malfunction diagnosis. These false diagnoses can result in unnecessary corrective actions in instances that required only simple “fixes”. Proper installation and functionality of a rotating machinery protection and monitoring system is essential for accurate diagnosis of machinery related malfunctions. For some gas turbine driven generator units, some monitoring system components can be internal to the machine and somewhat inaccessible. Monitoring system component problems and failures can result in obvious symptoms; however in a few instances these symptoms can be subtle and lead to a false or inappropriate malfunction diagnosis. These false diagnoses can result in unnecessary corrective actions in instances that required only simple “fixes”. This paper will discuss a recent case history involving chronic excessive vibration alarms and trips at a customer’s facility. Acquired vibration readings will be discussed. These measurements will illustrate the effects of subtle monitoring system component issues on machinery vibration levels leading to a potentially false diagnosis. Proper interpretation resulted in a correct diagnosis, thus avoiding unnecessary corrective actions.