The magnetic filter worked well on the return line from the pump internal lubrication of the pump.

Thomas Stalin

Wind Technology Expert, Vattenfall


Vattenfall is a market leader in both onshore and offshore wind, with over 50 wind farms in operation across Europe. In efforts to advance wind energy’s cost competitiveness and reliability, Vattenfall required a solution for reducing premature bearing failures in their turbine gearboxes.

Wind turbines create electricity when wind flows across the turbine blade and spins the motor. The rotor is connected to a generator directly in a direct drive turbine, or through a gearbox that speeds up the rotation and allows for a physically smaller generator.

Wind turbine gearboxes are susceptible to failure well before their designed service lives because 1) wind turbines consist of a dozen bearings that work simultaneously for years, and 2) the variability of wind patterns leads to fluctuating loads on wind turbine components. These failures are a major cause of downtime, unplanned maintenance, and parts replacement; they are the primary cause of increased opex for energy operators, and higher utility bills for customers.

76% of wind turbine gearboxes failed due to bearings, while 17% failed due to gear failures.

The National Renewable Energy Laboratory’s Gearbox Reliability Database (1)

In a feature article by the Society of Tribologists and Lubrication Engineers, Shawn Sheng, who is a member and Senior Engineer for NREL, states, “While gearboxes do not fail as often as electronic components in a turbine, they appear to be the costliest to maintain throughout a turbine’s 20-year design life. If not detected and mitigated early enough, these failures can lead to entire replacement of these gearboxes, which require costly crane rental expense, in addition to revenue loss, capital cost on new or upgraded components, labor and other costs, which dramatically increase the cost of energy for wind power, impacting offshore wind even more.”

According to the article, in 2007, NREL established the Gearbox Reliability Collaborative (GRC) to foster understanding of the root causes of premature gearbox failures and to improve gearbox reliability.2 GRC research has found that the faults in most prematurely failed gearboxes are related to bearing failures in the intermediate and high-speed sections, with much of that failure occurring in as little as 5%-20% of the bearing’s design life.2

Wear contamination is the root cause of gearbox bearing failures. Bearings have a tolerance of under 1 micron, which means that wear contaminants, under 1 micron in size, will fit between the shaft and begin to wear on the components causing increased contamination in the gear oil that ultimately leads to axial cracking, scuffing and smearing, micropitting and dents/indentations in the bearing.


Alex Priori with Renox S.R.L., a global importer and distributor of high-performance lubricants and magnetic filtration for compressors, pumps, turbines, gearboxes and engines, worked with Thomas Stalin, Senior Wind Technology Expert at Vattenfall, to determine the best solution for preventing gearbox failures. Priori recommended that Stalin deploy One Eye Industries magnetic filtration on the return line of the lubrication pump.

A unique benefit of magnetic separator element is that they catch non-magnetic particulate via the principals of static adhesion and cross contamination. Read this article for an explanation. In this application however, the majority of the contamination in the gearbox is ferrous, so Alex could comfortably guarantee that our magnetic filter would catch 95+% of the contaminants in the gear oil. Check out our technical specifications for an explanation on how we can make that guarantee.


The magnetic filter y-strainers were installed in 2018, and the success of this deployment would be determined by how much wear contamination the filters would collect.

The magnetic filter element collected large debris from a component failure, as well as significant wear contamination down to and below 4 microns in size. If left in the system, this contamination would cause gearbox component failure, and ultimately catastrophic turbine failure.

Since the deployment, Priori has been in discussion with Stalin regarding the implementation of OEI magnetic filtration on hundreds of other off-shore wind turbines.

We have been following them for 2 years and in the end, the OEI filters worked very well.

Alex Priori

Renox S.R.L.

Expertise in reducing maintenance

Our world has been flipped upside down with no clear indication that any industries will be operating regularly anytime soon. Our systems offer a solution to reduced maintenance and parts replacement, as well as minimized human exposure.


If you’re curious about an application for magnetic filtration, let’s set up a consultation for you and our technical team.

  1. NREL Gearbox Reliability Database. Available here.
  2. National Renewable Energy Laboratory. “Wind Turbine Drivetrain Reliability Collaborative Workshop.” Available here.