- Vattenfall operates over 1000 turbines across several European countries and seeks to standardize its approach to gearbox oil management to reduce costs and prolong gearbox lifetimes. - Gearboxes commonly fail after 2-5 years of operation, short of their 20-year design lifetime, due to contamination of the oil by wear debris. Clean oil is critical for protecting bearings from damage. - The presentation proposes developing a common standard for sampling gearbox oil, analyzing it, and evaluating results to detect problems early. It also discusses optimizing oil filtration and testing new oil types to further extend gearbox lifetimes.

1. Gearbox Oil Standard
VGB Powertech Operation and maintenance conference
Colone 24th february 2015
Thomas Stalin
2015-02-20

2. Confidentiality - Medium (C2)
Background
• Vattenfall has a long tradition handling oil, started its own oil laboratory in 1957
• Vattenfall has oil standards, Hydro and Nuclear and Distribution
• Vattenfall operates >1000 Turbines in DK, DE, NL, SE and UK
• Turbines are from ?? Suppliers and ?? Models
• Numerous Ways of handling oils today
• Gearbox is the part that has the highest part of O&M Life Cycle Cost
- Designed for 20 years life time but fails in practice in many times after 2 to 5
years and hardly none survive 10 years
- Run gearbox with clean oil?
- Prolong life time 50% or 3 times if compared to worst case
• Common approach on handling gearbox oil needed
• Increase the knowledge level about oil and oil cleanliness
• Optimize Oil Test Program
• Cost saving

3. Confidentiality - Medium (C2)
Generation Wind Gearbox Oil Standard
• Instead of having a country and turbine specific way of handling gearbox
oil we need a common approach
- Procedure for Sampling of Oil, site specific
- When to make sample
- What Analysis to be performed and specifications on how
- Which Laboratory to use and common purchase
- Internal database for results
- Enable Automated Evaluation of results together with CMS vibration
analysis and SAP data, type “Crystall Ball”

4. Related Oil Management Questions
• Introduction of offline filter analysis
• Early detection of problem with debris sensor
• Verification of filtration system
• When to change filters
• When to change gearbox oil and how to change it
• Test of new Oil types
Confidentiality - Medium (C2)

5. Confidentiality - Medium (C2)
Additiv kemi
Base oil
Additive
package
1-10%
Corrosion inhibitor
Anti foam agent
Demulsifier agent
AW + EP
(Detergent, Engine oil)
(Dispergent, Engine oil)
VI-improver
Pour Point Depressants
VI-improver
Antioxidant
Gearbox Oil
Base oil
- Mineral
- Polyalfaolefine
- Polyglycol
- Other

6. Confidentiality - Medium (C2)
Oil Cleanliness
• Gearbox oil needs to be clean and reach the level specified when
gearboxes were designed.
• Report “Oil Cleanliness in Wind Power Gearboxes, Elforsk report 12:52,
Jan Ukonsaari and Hans Möller”
• Oil film thickness 0,5 to 1,5 um, hair 17-180um
• 80% of machine wear particle induced
• Standard for counting level of particles ISO 4496:99
- 4, 6 and 14 um
• Online and offline filtration
- 16/14/11 to 13/12/9 Vf offshore wind farm
• Design level
- -/15/12 Vestas/Hansen
- -/14/11 Winergy
- 18/16/13 Literature
- Faults during commisioning can not be reversed
• Clean oil can not recover design faults on drive train

7. Confidentiality - Medium (C2)
Bearing life and particles
P
Particles in the EHL contact increase peak pressure
Elastic deformations
Increase sub surface fatigue, remaining
Dents reduce oil film
Create premature failure, spalling
Load dependent
Run in condition important

8. Confidentiality - Medium (C2)
Relative Bearing life, Particles

9. Confidentiality - Medium (C2)
Relativ Bearing life, Water content

10. TRAP Filter, Donaldsson
• Bearing manufacturers say that water in oil can severly damage
bearings.
- If gearbox survives 8 to 10 years maybee low water content can give
another 6 to 12 months life
- Why descissant filters on hydraulic system that cost 10 times less than
a gearbox ???
• Only Gamesa has descissant filters on gearbox ventilation
- Silica gel filter with limited capacity, work for 3 months not one year
• Instead Membran filter from Donaldsson
- From 400 PPM to 70 PPM Water
- Lasting >1 year
Confidentiality - Medium (C2)

11. Confidentiality - Medium (C2)
Oil Quality Test
• How to create an optimized oil test procedure?
- Create Value???
• At what time interval to make the test program?
• Which type of test to be used and at what time?
- Older smaller turbine
- Large existing turbines
- New planned large projects
• How to introduce one site specific procedure to take oil sample
- strictly to be followed
- Otherwise results not comparable . To high variability.
• How to specify the oil analyses
- Otherwise results not comparable and variability high.
- Quality control of results
• Which Lab to use?
- Common purchase
• Own Evaluation of Results from oil analysis and investigations from CMS system

12. Confidentiality - Medium (C2)
Optimized Oil Test Procedure
• During Warranty
- Follow Turbine Manufacturers Recommendations but adopt these so
that sampling and testing show reliable results
- Closely follow results during run in and warranty period!!!!
• After Warranty
- Decide to establish own procedures based on own experience and
turbine manufacturers recommendations
- Follow sampling procedure strictly
- Education of the importance of oil cleanliness and on sampling method
- Simplify procedures and have a common approach
- Optimize Oil Testing
• Database for results
• Own evaluation of results
- Together with CMS vibration analysis, SAP data and Chrystal Ball
methodology

13. Confidentiality - Medium (C2)
Oil Sampling Horns Rev

14. Confidentiality - Medium (C2)
Oil Sampling Horns Rev cont

15. Lillgrund, GBX sampling
Confidentiality - Medium (C2)

16. Lillgrund Sampling Eguipment
Confidentiality - Medium (C2)

17. Lillgrund Hydraulic Oil
Confidentiality - Medium (C2)

18. Confidentiality - Medium (C2)
Education, oil quality and sampling procedures
• Presentation of Oil management standard for:
- Site managers
- Service leaders
- Technicians
• Document present way of doing the job
- Discussing findings with involved persons
• Propose possible improvements
• Write site specific sampling procedure
- At the site together with the technicians
- =>> Large improvements, 1 to 2 ISO classes cleaner oil

19. Confidentiality - Medium (C2)
Oil Analyses
• Goals for analysis
- Check oil properties
- Check appropriate levels of additives
- Investigate machine wear
• Oil properties
- Viscosity
- Water content
- Acid number
- Foamability
- Emulgation
• Levels of Additives
- Anti Wear and Extrem Pressure
- Anti Oxidant
- Anti Corrosion Inhibitors
• Machine Wear
- Particle counting
- Levels of different element particles(atoms)

20. Confidentiality - Medium (C2)
Improve Evaluation of Results
• Need to make own evaluation of results from oil analysis
- Oil good enough to run another year/6 months?
- Prediction of gearbox breakdown?
• Or patient OK
• Or ???
• Or dying?
• Evaluation of
- Turbines in wind park
- Fleet of turbines same model
• Service leader together with:
- My support + Oil expert
- If CMS with CMS expert
Actions???
=>Create Value!!!

21. BukobaThomas
Confidentiality - Medium (C2)

22. Östra Herrestad V90 2 MW, 9 turbines
• 10 times higher particle content than recomended
• During EOW large particles found in offline filter, microscope inv.
- Cause not found and no Warrenty Issue
• Inline filter half cold, => half fílled with air >> Reduced filter function
Two years of no action, further wear and deterioation
• Rebuild process at year four
- Air release valve on inline filter
- Air release valve on offline filter
- Preassurising of offline filter, CCJensens/Stema
After 3 months 10 fold reduction of particles now all turbines better or
equal to 16/14/11.
Cost around 500 Euro/turbine
Confidentiality - Medium (C2)

23. Östra Herrestad continue I
• Endoscopy investigation show all bearing surfaces with dents
- Severly damaged, accelerated wear
• CMS system shows no indication of damages
• Oil analyses show perfect oil cleanliness now
- Before high particle content and especially large particle >30>50>70
um. Look into the oil analyse sheet and analyse this
information!!!!
- Large particles that should not be there and for which the gearbox
bearings was not designed for. With inline filter 10 um and beta 200.
- Offline filter analyses show large particles 100x100x100 um
- Microscopy investigation of particles in oil show 500 um hairline
extruded particles
• Outer bearing ring rotates and releases particles that destroy bearing
surfaces
• Outer ring fixation shaves off very long particles that breaks into smaller
particles that are transported through the bearing
Confidentiality - Medium (C2)

24. Östra Herrestad continue II
• Original offline filter design HDU15/25 to small, designed for V52, 850
kW
• Particles accumulate at inline filter
- At start and stop large amount of large particles recirculated
- >>create severe damage
- Finnish research paper:
• Second rebuild:
- Double flow 120 to 250 liter/h
- 8 fold increase of filter area, HDU 27/54
- Magnetic filter in the main circuit
- >> Catch all large particles and stop recirculation of particles
By removing larger particles the speed of deteroation will slow down
- Increase life by 6 to 12 months or more
- Change to medicine oil with better additives: Duolec LE or Rewitech
Confidentiality - Medium (C2)

25. Confidentiality - Medium (C2)
Oil Exchange
• Oil should be changed based on Oil Quality Properties
- Instead of exchanging an oil based on yearly intervals
- Dialog with turbine manufacturers, gearbox suppliers and oil
companies should be started. Right conditions not known!!!
• After five years the oil sample should be sent in for full analyze
- If Quality is acceptable good, the oil should be used for another
1year/6 months.
- When Oil reaches end of life it should be tested every 6 months.
• Oil refilling procedures
- Oil should be filled via a filter with minimum oil cleanliness -/14/11 and
acceptable level of oil cleanliness should be reached before turbine is
taken in full operation.
- Oil should not be filled through open cans into gearbox
• Batch of new oil analysed before filling

26. Confidentiality - Medium (C2)
Exchange to New type of oil
• During 20 years oil technology will improve with new formulas
- Lower wear due to AW and EP aditives
- Lower friction >>> higher production 0,5 to 1%
- Vattenfall should try to improve the production by using new oils
• The specified oil for the gearbox has been chosen after a long test 3-5
years to approve new gearbox oil
• VF have had experience of large problems after changing from one type
of gearbox oil to another type.
- Long test had been made but small change in oil formula made new oil
forming glue like components when mixed with old oil
- Great Care Needed!!!
• Change to new type of oil shall only be done after consultation with
Vattenfall experts and careful testing. Permission should be needed.
• Common program to test and evaluate new type of oil formulas
• 1) Polyalfaglycol Dow Ch., 2) Eco Gear Addinol, 3)Duolec LE,
4)Rewitech

27. VGB Powertech proposed Research Topics
Research projects:
• Testing of present and new gearbox oil formulas
• When to change gearbox oil
• How to interpret results from wear debrice sensors, ei Gastops sensors
• How to extend the fying out period by use of oils with special additives
and increased filtration and different control strategy
Best practises:
• Gearbox oil management
• Interpretation of gearbox oil analyses
Standards:
• Format for reporting of oil analyses results
• Oil analyses for Wind Turbine Gearbox oils
Confidentiality - Medium (C2)

28. Please contact me to discuss oilmanagement!!!
Confidentiality - Medium (C2)