Monitoring on low-speed components lubricated with grease

Second meeting 15th of November 2022


The wind industry is totally missing monitoring on low-speed components lubricated with grease. First, it is generally assumed that injecting new grease is sufficient to ensure good lubrication, then that a sealed bearing housing will prevent any pollution. The main challenge is to bring grease analyses to a sufficient level to establish some statistics correlating wear particles nature, count and sizing with the health of the main bearings and the pitch bearings. It should allow estimating very early if the expected life according to IEC 61400-1 can be reached or not.



In general, we want to explore which benefits we could have from monitoring grease lubricant in low-speed components. The aim is to understand if we could get a better understanding of our assets and components' lifetime by implementing some sort of monitoring of low-speed components in our wind turbines. If we see potential in this, then the owners who carry these risks should push for this issue to become more relevant on the agenda of our dear industry and create or improve given standards. 



An introductory case study is given by Rémi Stein, Senior Machinery Expert at ENGIE.



We want to look closer at two questions: 

  • Is my lubricant clean enough to ensure the longest possible life?
  • If hard particles are found, is it due to early wear or external pollution and how can I mitigate it to avoid further deterioration?

To answer these questions trends should be drawn from the commissioning on a yearly basis. It will probably be the earliest information that can be collected about bearing health due to the ability to detect very fine particles nature from spectroscopy.

Main bearings, pitch bearings and yaw bearings are suffering unorthodox operating conditions such as freewheeling and stand still, those are very bad for lubrication as there is no chance for a hydrodynamic film to build up. Then even the tiniest particles will be laminated and can initiate microcracks in the raceway material that will develop later under a fatigue process.

Grease lubricant is not yet with a standard about cleanliness and relies on state of the art and good practices applied in all industries with mechanical components. Unfortunately, this is for now rejected by wind turbines’ OEMs. Most of them claim that feeding new grease on a regular basis is sufficient.


Roundtable format - Maximum Seven Participants

For this meeting, we want active engagement from knowledgeable experts and will only allow seven participants. Rémi will set the table and thereafter the discussion will open up for all participants.


Target group

This roundtable discussion is exclusive to wind turbine employees and targeted towards those persons who have within their responsibilities to develop and apply optimal procedures for grease-lubricated components such as main bearing and pitch bearings and eventually yaw bearings.


15th of November 2020. Duration: 1 hour. Starts at: CEST – Stockholm, Hamburg, Madrid at 4 pm; AWST – Perth at 11 pm; AEDT - Sydney, Melbourne 2 am; BST – London, Dublin at 3 pm; CDT - Houston, Chicago at 9 am; GMT-3 - Montevideo, Rio de Janeiro at 11 pm.


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