Reduced iron levels and lower PQ index

The challenge 

A 1.5 MW wind turbine gearbox showed persistent contamination risk despite routine oil analysis. To understand the true internal condition of the gearbox, debris captured inside an offline filtration unit was analysed after extended in-service operation. Standard oil samples alone were not showing the full extent of varnish, wear debris, and moisture present within the system.  

Customer savings & impact 

Physical debris analysis from the Delta-Xero DX1001-W filter provided clear, verifiable evidence of contamination removal: 

• ≈ 3.8 kg of debris captured in a single filter after 11 months of operation 

• High iron and wear debris levels confirmed (PQ index > 100), indicating significant gearbox contamination previously circulating in oil 

• Varnish and moisture removed at operating temperatures, restoring the oil’s ability to clean internal gearbox surfaces over time 

Follow-on filter analysis showed reduced iron levels and a lower PQ index, confirming progressive gearbox and oil condition improvement. The full case study shows what was trapped inside the filter, how contamination levels reduced over time, and why continuous filtration delivers long-term protection.  

Download the complete wind turbine gearbox debris analysis case study, including micropatch images, debris weights, and ferrography evidence.