Here's a video of a small Nordtank turbine (Nordtank were bought and integrated into Vestas) being destroyed during some of the heavy wind activity we had here in Denmark last month.
According to the Danish engineering publication Ingeniøren (the engineer), the turbine was an old Nordtank N500/41 - a 500kW stall turbine with a 41m rotor diameter and 43m hub height tower. As stall turbines have a fixed blade pitch, the safety system relies on pitching the blade tips to fully stop the turbine and then yawing into the wind.
Apparently the blade-tips were sheared off during operation some time before the accident, and there was therefore no way to shut down the turbine. Luckily, the local council (kommune) was aware of the problem and cordoned off the surrounding area. Good decision, as it was reported that large pieces of the blade flew up to 400m - not suprising when you see the video.
In the video you can see the turbine spinning at high RPM, and then something thrown off the blade (kicking up dirt on the ground) and then all the blades disintegrating. The huge imbalance that occured during the blades failure sheared the bolted tower section as well. No suprise the turbine failed here, with incredibly high centrifugal loading on the blades, needless to say the turbine is a total write off.
You can read the article (in Danish) here.
Sunday, March 2, 2008
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2 comments:
Hi, I saw ur blog and find it interesting, I had a question for u , are there any trends that you have spotted on maintaining the wind turbines Or the costs associated with the same. even some referred URL might help me ...thanks
Hi Vindy,
There's quite a few public domain papers I know of with some decent operation and maintenance data: both effects on availability and costs. I'll dig em up.
My next post was going to be on detailed stall turbine aerodynamic design, however I could write a post on O&M - anyone else interested?
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