Ecol4wind insights (part 2):
Bearing. Main not only in name.

main bearing: a critical point for turbine reliability

A single bearing can determine millions in OPEX. This is because it is an absolutely critical component in the system that transfers torque from the blades to the gearbox and generator. It is also one of the key and most damage-prone components of the entire wind turbine. Its failure can be catastrophic. In the best case scenario, it means forced downtime and costly replacement. In an extreme scenario, it can lead to fire and permanent loss of turbine operational capacity.

monitoring and responsible operation

In one of our next articles, we will focus on failures and their causes. For the purposes of this post, we will limit ourselves to what seems to be an obvious statement: ‘monitoring and responsible operation are essential’. That is all there is to it. Despite its apparent simplicity, the applicability of this thesis is not obvious or straightforward. What is ‘monitoring’ and ‘responsible operation’ in the context of a main bearing? There is probably no universal answer, but below we present our approach.

reliability is a matter of probability

Firstly, it should be mentioned that reliability is a function of probability, which means that, firstly, there is a random factor in this puzzle and, secondly, our task is to minimise it. The choice of bearing remains with the manufacturer, as do the operating assumptions. However, the owner and service provider have a real impact on the quality of inspection and operational maintenance. It is in the area of inspection and service that we see the greatest potential for reducing the risk of failure, in line with the philosophy of proactive maintenance.

lubricant as an information carrier

Oil or lubricant in a machine can be compared to blood in the human body. In both cases, fluid analysis can tell us a great deal about the condition of its user. In grease, we do not measure haemoglobin or CRP, but the content of solid particles, the level of oxidation and the consistency. These parameters are indicators of the quality and service life of the lubricant and, indirectly, the condition of the bearing. Regular testing allows service decisions to be made at the optimal time – from the point of view of safety and costs.

bearing flushing as a tool for extending service life

Every mechanical component wears out over time. Our task is to slow down this process. During operation, both the lubricant and the bearing material degrade. At the right moment, an effective solution may be bearing flushing – replacing the grease and removing wear particles. New grease and clean surfaces help to ‘reset’ the bearing, reducing the likelihood of failure and thus increasing its reliability. Experience shows that one year after the service, the level of contamination decreased by up to 80% compared to the initial state. However, for this to be effective, the process must be carried out in accordance with best practice and using the right consumables.

prevention costs vs failure costs

A main bearing failure can generate costs exceeding one million zlotys. This is OPEX, which significantly affects the profitability of a project and, in extreme cases, can determine its viability. In turbine operation, as in medicine, a simple rule applies: prevention is better than cure. Referring to the title, the bearing is not main only in name. In many cases, it determines the further life of the turbine. In subsequent articles, we will focus on damage mechanisms and discuss other aspects of O&M in wind turbines.

Author of numerous scientific publications and commercial projects implemented for the energy sector. Former lecturer at the Silesian University of Technology and the Krakow University of Technology.

At Ecol Sp. z o.o., he serves as Director of Business Development for services dedicated to the wind industry as part of the Ecol4Wind programme. He is responsible for developing the offer, cooperating with clients and setting strategic directions for the development of solutions for wind energy.