Fault Prediction of Centrifugal Pump Based on Improved KNN

Table 1

Time-domain feature.

Evaluation index	Formula	Significance of evaluation
RMS		Represents the average amount of signal amplitude based on a unit of time
Kurtosis coefficient		It can express the difference between the signal and its average value at this time
Peak factor		Dynamic expression of the damage to the surface of the machine seal
Pulse factor		The ratio of the peak value to the mean value of the signal, the criterion for judging the presence of an impact in the signal
Waveform factor		Based on the upper root mean square value and the mean value ratio of the time-domain
Kurtosis		The amplitude of the seal acoustic emission signal is described. If the kurtosis is too large, it means that there is a dry friction
Margin coefficient		The ratio of the signal root means a square value to its mean value, used to evaluate the degree of component damage
Skew coefficient		The asymmetry degree of acoustic emission signal is described
Center frequency		Denotes the change in the position of the power spectrum barycenter and describes the change of the energy ratio of each frequency component
MSF		Represents the discrete state of power spectrum energy distribution and describes the composition of signal frequency components