In order to accurately monitor the operation state of centrifugal pumps

mathematic model for online monitoring and fault diagnosis of the operation state was established

and an online monitoring and fault diagnosis device for centrifugal pumps was also developed. With the functions of running state monitoring and fault diagnosis on line

this device can monitor the volume flow

inlet pressure

outlet pressure

pump head

power

efficiency

axial displacement and radial displacement of the centrifugal pump online. Moreover

the running state can be displayed in forms of graph

histogram and table. The fault diagnosis function includes initial diagnosis and accurate diagnosis. The initial diagnosis adopts threshold contrast method to identify the four faults of cavitation

foundation looseness

rotor misalignment and rotor imbalance. The accurate diagnosis classifies the faults as mild

moderate and severe according to the empirical mode decomposition(EMD) energy entropy. The results show that this device can monitor and diagnose the operation state of the centrifugal pump accurately.