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This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications.
List of Figures
Figure 1. SKF SRB-Wind main bearing (left) and instrumentation (right). Photos by Jonathan Keller
and Jerry Hur, NREL 49379 and 49959 ............................................................................................... 2
Figure 2. Winergy PEAB 4410.4 gearbox side (left) and rear (right) view. Photos by Jonathan
Keller, NREL 49044 and 49045 ............................................................................................................ 3
Figure 3. High-speed-shaft instrumentation schematic .......................................................................... 4
Figure 4. Gearbox swap (left) and installation in turbine (right). Photos by Dennis Schroeder,
NREL 49409 and 49413 ........................................................................................................................ 6
Figure 5. Normal power production data acquisition durations ............................................................ 9
Figure 6. Power (left), rotor speed (middle), and blade pitch angle (right) in normal power
production ............................................................................................................................................. 9
Figure 7. Main bearing proximity probe raw (left) and filtered (right) measurements in a normal
power production case ...................................................................................................................... 10
Figure 8. Main shaft net axial motion in normal power production ..................................................... 11
Figure 9. Main bearing generator-side (left) and rotor-side (right) electrical current in a normal
power production case ...................................................................................................................... 11
Figure 10. Main bearing generator-side (left) and rotor-side (right) stray electrical current in normal
power production ............................................................................................................................... 12
Figure 11. High-speed-shaft generator-side-in (left) and rotor-side (right) bearing roller speed in
normal power production cases ....................................................................................................... 12
Figure 12. High-speed-shaft generator-side-in (left) and rotor-side (right) bearing cage speed in
normal power production cases ....................................................................................................... 13
Figure 13. High-speed-shaft generator-side-in (left) and rotor-side (right) bearing roller speeds at
900 rpm and 257 kW ........................................................................................................................... 14
Figure 14. High-speed-shaft generator-side-in (left) and rotor-side (right) bearing roller speeds at
1,220 rpm and 600 kW ........................................................................................................................ 14
Figure 15. High-speed-shaft generator-side-in (left) and rotor-side (right) bearing roller speeds at
rated speed and power ...................................................................................................................... 15
Figure 16. High-speed-shaft generator-side-in (left) and rotor-side (right) bearing roller speed in
normal power production .................................................................................................................. 15
Figure 17. High-speed-shaft generator-side-in (left) and rotor-side (right) bearing cage speed in
normal power production .................................................................................................................. 16
Figure 18. Unfiltered high-speed-shaft torque in normal power production ...................................... 16
Figure 19. Filtered high-speed-shaft torque in normal power production .......................................... 17
Figure 20. Filtered high-speed-shaft Y (left) and Z (right) bending moment at B in normal power
production ........................................................................................................................................... 17
Figure 21. Filtered high-speed-shaft Y (left) and Z (right) bending moment at C in normal power
production ........................................................................................................................................... 18
Figure 22. Gearbox and generator stray electrical current in a normal power production case ...... 18
Figure 23. High-speed-shaft generator-side-out (left), generator-side-in (middle), and rotor-side
(right) stray electrical current in normal power production ........................................................... 19
Figure 24. High-speed-shaft generator-side-out (left), generator-side-in (middle), and rotor-side
(bottom) bearing outer raceway temperature in normal power production ................................. 19
Figure 25. Gearbox oil water activity (left) and temperature (right) in normal power production .... 20
Figure 26. Gearbox air and dew point temperature difference during normal power production .... 20
Figure 27. Main shaft torque and speed during a normal startup ........................................................ 21
Figure 28. Main bearing axial motion during a normal start-up ........................................................... 22
Figure 29. Main bearing generator-side (left) and rotor-side (right) stray electrical current during a
normal start-up ................................................................................................................................... 22
Figure 30. High-speed-shaft generator-side-in (left) and rotor-side (right) bearing roller speed
during a normal start-up .................................................................................................................... 23
Figure 31. High-speed-shaft generator-side-in (left) and rotor-side (right) bearing cage speed
during a normal start-up .................................................................................................................... 23
Figure 32. High-speed-shaft torque and speed during a normal shutdown ....................................... 24
Figure 33. Main bearing axial motion during a normal shutdown ....................................................... 24