What is a wind class?

    When it comes to wind turbine performance, location matters. Turbines need to be designed for optimal performance and reliability in whatever weather conditions they may face throughout their lifetimes, be it a gentle breeze on a low-lying plain or a raging offshore storm.

    Before deciding to build a wind turbine in a particular site, there are a few critical questions the developer needs to answer: What is the average annual wind speed in this location? What are the extreme gusts that could occur within a 50 year period? How turbulent is the wind at the site?

    These three dimensions — wind speed, extreme gusts, and turbulence — encompass the wind class of a wind turbine. The International Electrotechnical Commission (IEC) sets international standards for the wind speeds each wind class must withstand, as seen in the table below.


    How does this impact blade design?

    To put it simply, blades in high wind sites and low wind sites have different designs to optimize performance. For instance, turbines in lower wind speed locations (Wind Class III) at a given rated power will need a larger rotor to capture the same amount of energy as a similar turbine at a Class II site. Fortunately the milder wind climate makes it possible for the turbine structure to carry a larger rotor, and thus an efficient turbine can be designed. Even so, the cost of energy will always be lower for wind power at sites with a higher average wind speed.

    The choice of wind class occurs early in a blade project, with the customer making the decision about the wind class based on the intended site. According to LM Wind Power’s Peter Hansen, Senior Project Manager for Technical Business Development, Wind Class II and III are most common, though this is changing over time. 

    “The main difference between wind classes is in the loads, which the customers calculate and give to us,” Peter said. “There is a clear trend in the market toward more Wind Class III turbines in low wind sites, and the explanation is simple: there are not many Wind Class I and II sites left!” 


    What are the wind classes of our blades?

    Customers’ desires, and consequently our blade designs, are not static over time. When we design a blade for a customer, sometimes they want to use it on turbines in a different environment than the original site, which may be more windy or turbulent.

    “We may design blades for the same customer in the same length, but with different wind classes and different masses,” Peter said. For example, the LM 58.7P is in Wind Class III, while the LM 58.7P2 is in Wind Class II. Though both blades are 58.7 meters in length, the blade mass differs: 13320 kg for the LM 58.7P and 13770 kg for the LM 58.7P2. 


    References: 

    What is the wind class of a wind turbine?

    IEC Wind Turbine Classes

     

    Share this page

    Learn about wind

    Ask us about wind

    Industry and technology insights from our experts.

    Sustainability

    The Case for Wind

    In 10 Blade Points

    Wind power, renewable energy, climate change, sustainable business practices - there are many hot topics surrounding our business, and it's time we voiced our opinion.

    Career

    Get the wind behind your career

    We are always looking for new, talented colleagues.

    LM Wind Power is a pioneer in the Danish wind industry and the world’s leading independent supplier of blades for wind turbines, with 15 factories on four continents. We have all technical disciplines in-house:  materials laboratories, design and modelling, a wind tunnel, full scale testing and production. Explore the exciting positions available.

    15-01-2019 12:00:38 | linkedin

    We've installed a total of 1.7 GW of offshore wind capacity - that's equivalent to powering 28 million light bulbs! Learn more about our offshore track record: https://www.lmwindpower.com/en/products-and-services/blade-types/go-offshore-lm-wind-power
    15-01-2019 12:00:36 | twitter

    We've installed a total of 1.7 GW of offshore wind capacity - that's equivalent to powering 28 million light bulbs! Learn more about our #offshore track record and why #WeKnowBlades: fal.cn/rLvy
    15-01-2019 12:00:00 | instagram
    Did you know - we've installed a total of 1.7 GW of offshore wind capacity. That's equivalent to powering 28 million light bulbs! #LMplaces #lmwindpower #Offshorewind #greenbusiness #wind #windworks #windturbine #windturbines #renewables #windpower #windenergy #renewableenergy #cleanenergy #future #sustainability
    11-01-2019 14:00:36 | linkedin

    "I admire what a rich resource we have in wind energy. I believe we can have a cleaner world by producing clean energy". Maristela Ruana da Silva is part of the Laboratory Quality team from our Suape plant in Brazil. She takes pride in ensuring that all raw materials and the calibration equipment used for the production process is in perfect condition. It helps us guarantee high quality blades for customer satisfaction. Read on to learn more about how #WeKnowBlades: https://www.lmwindpower.com/en/products-and-services/we-know-blades
    11-01-2019 14:00:33 | twitter

    "I admire what a rich resource we have in wind energy. I believe we can have a cleaner world by producing clean energy". Maristela Ruana da Silva is on the Laboratory Quality team in Suape, Brazil. Learn more about how #WeKnowBlades fal.cn/rW.w
    11-01-2019 14:00:14 | instagram
    "I admire what a rich resource we have in wind energy. I believe we can have a cleaner world by producing clean energy" - Maristela Ruana da Silva is part of our Laboratory Quality team in #Suape, Brazil. She is always looking to ensure that all raw materials and the calibration equipment used for the production process is in perfect condition. #WeKnowBlades #LMplaces #lmwindpower #Brazil #greenbusiness #wind #windworks #windturbine #windturbines #renewables #windpower #windenergy #windfarm #renewableenergy #cleanenergy #future #sustainability #engineering
    07-01-2019 12:00:20 | linkedin

    Our global presence means we can serve our customers in all established and emerging wind markets. A recent visit to our Indian plants in Vadodara and Dabaspet, as well as our Technology Center India, gave the executive management team a great opportunity to see how our colleagues are ready to meet the demands of future growth! Learn more about how #WeKnowBlades https://www.lmwindpower.com/en/products-and-services/we-know-blades/global-presence
    07-01-2019 12:00:16 | twitter

    Our global presence means we can serve our customers in all established and emerging wind markets. A recent visit to our plants in India gave the executive management team a great opportunity to see how our colleagues are ready to meet the demands of future growth! #WeKnowBlades
    04-01-2019 13:09:29 | twitter

    Offshore turbines have grown 30 times in #Denmark over the past 25 years and is expected to grow even more with falling #LCOE as a result. From 0,45 MW to 13-15 MW! #windpower #renewables #renewableenergy #windworks #windturbines
    21-12-2018 10:56:30 | instagram
    As many LM Wind Power colleagues gear up for the holiday season, our very own Sustainable Santa wants to share some of our key highlights of 2018! http://www.sustainable-santa.com #CleanLM #lmbalance #WeKnowBlades #LMplaces #lmwindpower #greenjobs #Balance #greenbusiness #wind #windturbine #windturbines #renewables #windpower #windenergy #renewableenergy #cleanenergy #sustainability #CaseForWind
    Fill 1