Wind turbines – the ultimate test of quality and performance in drive
Wind turbine driveline components have to perform to very high standards. They typically need to give twenty years – or 175,000 hours – of maintenance-free service in harsh conditions and under highly dynamic, irregular loads.27 Feb 2015
Consequently, wind energy technology is a badge of engineering excellence for manufacturers of high-end drive components and systems. If their products are good and tough enough to convert wind into electricity day in, day out in demanding onshore and offshore environments, then they're sure to be in demand for heavy-duty applications in many other industries as well.
German power transmission specialist KTR Kupplungstechnik GmbH is a good case in point. The manager of its "Core and Engineered Business" units, Dr. Norbert Partmann, explains: "Our steel laminae couplings are widely used in the wind energy sector all over the world. We started out about twenty years ago with driveline components for 250 kW turbines, and now the range goes right up to 7 MW." Over those 20 years, KTR has supplied couplings for more than 40,000 wind turbines. At MDA 2015, it will showcase the latest generation of these rugged couplings, which it is increasingly supplying as complete subassemblies comprising various brake systems. KTR has developed several types of these integrated systems specifically for wind turbines, and the latest units can generate braking forces of up to 1.6 N or 160 tons each. KTR will also present couplings that can transmit the high levels of torque that arise in medium-speed turbines with one to two gears and multi-pole generators.
The trend towards integrated systems is also evident from the wind turbine products made by Parker Hannifin. Its Business Development Manager, André Herrmann, outlines his company's approach: "Manufacturers and operators of wind turbines are very much interested in minimizing their asset and maintenance costs and maximizing plant efficiency. Suppliers of drive technology can help them achieve these goals by providing integrated solutions. Increasingly, integrated wind turbine solutions also include energy storage functionality, which is a new trend. So, in addition to complete hydraulic assemblies, pitch adjustment systems, braking systems, filters and connectors – which we combine to create fully tested assemblies – we also provide turnkey battery storage solutions. We will be showcasing our expertise in integrated systems at the upcoming HANNOVER MESSE show."
Similarly, the Wind Power unit of the international driveline and chassis technology provider ZF (ZF Friedrichshafen) will be using HANNOVER MESSE to present its latest developments in wind turbine gearboxes. Among them will be a new generation of 3 MW-class gearboxes with integrated cone-shaped planetary gear assemblies. These gearboxes can operate in a torque range of 2,000 to 3,100 kNm.
Wind energy experts will use HANNOVER MESSE to share information on new products and discuss current industry trends and challenges. One such challenge is premature failure of drive components, particularly antifriction bearings, due to a phenomenon known as white etching cracks (WEC) – the formation of cracks with telltale white edges.
Some of the world's leading manufacturers of antifriction bearings have been undertaking a great deal of research into this problem, and the first solutions will be on show at HANNOVER MESSE. Matthias Schramm, Head of Renewable Energy & Commodities at Schaeffler Technologies GmbH: "We've developed an efficient, cost-effective technology for reducing WEC damage. It involves a combination of through-hardening the bearing and black-oxide coating the outer and inner rings and the rollers."
The black oxide coating developed by Schaeffler is called Durotect B. It reduces the risk of damage through slippage and sliding, improves run-in behavior, and offers protection against corrosion and, of course, WEC. The technology can also be used on bearings made of Mancrodur® carbonitrided steel (32MnCrMo6-4-3), which have even higher load ratings.
Another solution to the WEC problem is to make the bearings from a special high-performance steel called Cronidur 30. According to Schaeffler, the use of Cronidur 30 can completely eliminate the risk of WEC. Matthias Schramm explains: "We have never encountered a case where Cronidur 30 bearings have failed due to WEC. The material also increases the load rating by up to 70 percent, thereby extending bearing service life and enhancing corrosion protection." Alongside Schaeffler, visitors at HANNOVER MESSE 2015 are certain to discover numerous other antifriction bearing manufacturers who have developed solutions to the very common problem of WEC.
And speaking of certainties, there's no doubt that the colossal level of investment that drive technology manufacturers have been putting into durable, high-performance components for wind turbines also pays dividends in other industries. Dr. Norbert Partmann, Manager Core and Engineered Business at KTR Kupplungstechnik GmbH, explains: "The standards for testing, certification and QM documentation in the wind energy technology sector are extremely high. For example, a specification document for a coupling can be anything up to 180 pages long." In other words, if you see a drive component or system on display at HANNOVER MESSE, you can be sure it has been developed for extremely high loads and thoroughly tested.
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