# Design of a Novel Electric Diagnostic Technique for Fault Analysis of Centrifugal Pumps
## 3 Results and Analysis  
The d-q patterns of the two-phase currents were plotted using the EDT programmed in LabVIEW. The plot of the healthy pump is shown in Figure 6, and the d-q plots of the impeller faults and pipe blockages are shown in Figure 7; Figure 8, respectively. Figure 5: Impeller faults and pipe blockages. Figure 6: d-q pattern of the healthy pump. Figure 7: d-q pattern of the pump with impeller faults: (**a**) impeller fault type 1; (**b**) impeller fault type 2; (**c**) impeller fault type 3. The d-q patterns, shown in Figures 6-8, for the various health conditions of the centrifugal pump, could be analyzed on site by machine operators through a visual comparison of the various patterns. This visual comparison can give information to machine operators about the health condition of the pump, and they can then plan the maintenance for any upcoming failure. On the other hand, a statistical analysis of the various patterns was also performed for automatic decision making regarding the centrifugal pump health. The statistical analysis technique, based on the calculation of the splitting factor of the curve, was used in this paper for the analysis of the d-q patterns of the pump [14]. The mathematical model of the splitting factor is included in the Appendix A. The algorithm for calculating the statistical parameter (splitting factor) was incorporated in the LabVIEW-based EDT, and the results are shown in Table 1.  
Figure 8: d-q pattern of the pump with a pipe blockage: (**a**) half pipe block; (**b**) full pipe block. It has been observed from Table 1 that each type of centrifugal pump fault has its unique splitting factor, and the splitting factor increases with the increase in fault severity. Thus, the centrifugal pump health could be estimated, and various fault types could be segregated based on the curve splitting factor. The uniqueness of the splitting factor of the impeller faults and pipe blockages has been confirmed by comparing the results with other fault types, and this is shown in Table 2. The authors of [14] calculated the splitting factor for the outer race and inner race faults, which were reported to be 1.75 and 1.70, respectively. The splitting factor for a motor winding inter-turn short circuit was shown to be 1.8 [29]. Similarly, the splitting factor for a motor eccentricity fault was shown to be 1.64 [30]. The current study calculated the splitting factor for three fault levels of impeller faults and two levels of pipe blockages. The splitting factor values were unique for each fault type. Thus, the splitting factor information could be used in online fault diagnostic applications for the identification and segregation of various fault types. The superiority of EDT has been compared with other published techniques in order to verify the importance and usability of EDT in centrifugal pump fault diagnostics. The vibration analysis technique was used by the authors of [7; 11] to diagnose seal damage and cavity faults in pumps. Although vibration analysis has been proven to be a reliable diagnostic technique, it is an intrusive technique, as it requires expensive sensors that need access to a pump's installation location for data collection. Furthermore, vibration analysis cannot be used by machine operators for the on-site analysis of pump health, and requires an off-site analysis of the data by experts. A non-intrusive fault diagnostics technique based on MCSA was developed by the authors of [17; 18]. They diagnosed impeller faults, and showed that their proposed technique is the best possible alternative to the vibration analysis technique. However, MCSA cannot be used for on-site diagnostics by machine operators, and it needs experts for the off-site data analysis and interpretation. The MCSA-based diagnostics use frequency models that are not available for pump impeller and pipe blockage faults. Furthermore, MCSA signatures are suppressed under large amplitudes of environmental noise.