Measurement of shaft vibration using ultrasonic sensor in sump pump systems

Conventional diagnosis methods for bearings use acceleration sensors. But, the diagnosis method cannot be applied when the bearing is invisible like in sump pump systems in nuclear power plants. For such a case, diagnosis can be achieved by measuring the vibration of the shaft. Although an eddy current sensor (displacement sensor) is applicable to the monitoring of the vibration of the shaft, a high level of working is needed on the casing surrounding the shaft in the sump pump systems. With the application to the diagnosis of the bearing in sump pump systems in mind, the paper proposes a signal propagation model based diagnosis method for the shaft vibration using an ultrasonic sensor which is attached on the outside of the casing. The effectiveness of the method is finally demonstrated with simulations.