# A Robust Wind Turbine Component Health Status Indicator
## 3 Results
### Results Site 2  
In the case of site 2, the results obtained from applying the proposed methodology to two faulty gearbox cases (S2_GBX_F1, S2_GBX_F2) and six gearbox healthy cases (S2_GBX_H1, S2_GBX_H2, S2_GBX_H3, S2_GBX_H4, S2_GBX_H5, S2_GBX_H6) are presented. As an example of the behavior of the methodology applied through the values obtained from the \(Fl\) index, the graphs in Figure 11 are shown. In these graphs, the range of \(Fl\) values in all the healthy cases analyzed at the site can be observed. From the analysis of this figure, the expected behavior of the health index is confirmed: in general, the healthy state of the component corresponds to \(Fl\) values equal to or less than 50. The subsequent paragraphs provide the examination details of temporal evolution for the \(Fl\) and the selected SCADA signals. **Site 2, Faulty case 1 (gearbox)**: Figure 12a shows the generated \(Fl\) signal starting from 3 months in advance to the gearbox failure occurrence in S2_GBX_F1. In this case, a major  
Figure 11: Failure Index Evolution (\(Fl\)). Components in a healthy working mode. Site 2. Figure 10: Site 1, Time evolution Failure Index (gearbox). (**a**) Site 1, Faulty case 3 (gearbox). (**b**) Site 1, Healthy case 3 (gearbox). gearbox failure was reported on 7 May 2014. From the last week of March 2014, the gearbox oil mechanical pump pressure signal had been lost. Before the occurrence of this clear anomaly, from February 2014 to the last week of March 2014, failure propagation can be tracked by the FI; hence the _FI_ has a clear accelerating upward trend. **Site 2, Healthy case 1 (gearbox)** presents the analysis performed in the healthy working period of S2_GBX_H2. Figure 12b shows the _FI_ trend and the SCADA variables under consideration. The _FI_ ranges between 21% and 40%. In accordance with the FI, the SCADA signals do not show signs of abnormal working. The SCADA signals do not exhibit significant gaps during the analysis period. There are no significant mean changes in the time series of these signals. Only during the last week of November do the means of the SCADA signals increase slightly. As a general assessment of this case, if we compare the failure case and the healthy case, it can be seen that the range of _FI_ values is notably higher in the failure case, increasing notably the closer we are to the registered time of failure. Therefore, it can be concluded that the model is sensitive enough to differentiate between healthy and failure cases. **Site 2, Faulty case 2 (gearbox)**: Figure 13a shows the generated _FI_ signal starting from 3 months in advance to the gearbox failure occurrence in S2_GBX_F2. In this case, a major gearbox failure is reported on 5 June 2014. Tracking the SCADA signals from the last week of May 2014, it is possible to observe anomalies in gearbox oil input pressure, gearbox oil mechanical pump pressure and gearbox oil electrical pump pressure. Tracking the _FI_ from March 2014 to the last week of May 2014, it is possible to foresee the failure propagation; hence _FI_ ranges between 40% and 70%. **Site 2, Healthy case 2 (gearbox)**: covers the analysis performed for the healthy working period of WT5S2. Figure 13b shows the _FI_ and the corresponding SCADA signals for the healthy case 2. The _FI_ ranges between 32% and 44%. In comparison to the healthy case 1 (Figure 12b), the mean _FI_ is greater. The maximum _FI_ value was observed in mid-December, while the mean changes in the SCADA signals appeared in the last week of November. As also observed in healthy case 1, the mean of wind speed and the other SCADA signals increase. This similarity between the healthy cases indicates the working behavior of the  
Figure 12: Site 2, Time evolution Failure Index (gearbox). (**a**) Site 2, Faulty case 1 (gearbox). (**b**) Site 2, Healthy case 1 (gearbox). wind turbine when the wind blows between 15 and 25 m/s. Thus, it could be concluded that there were no abnormal working indicators within the analysis period.