Large Windmill collapse in NH

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  • westbranchwestbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: Large Windmill collapse in NH

    good links Bill, I watched both and noticed that in both cases, the tower base section remained intact, even though a 50 Ton , assuming both are about the same size. spectacular self destruction in Denmark. 8)

    Have seen many of those units and they are , in some cases, very close to homes, lucky that one did not injure someone.

    Eric
     
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  • BB.BB. Super Moderators, Administrators Posts: 32,921 admin
    Re: Large Windmill collapse in NH

    This is the problem with Stressed Skin type designs. They are very strong until the skin is damaged (in these cases, the blades appeared to collapse the skinned structure)--then there is virtually zero strength.

    The failures where the base failed would seem to indicate that the blades never touched the tower but other effects (such as vibration transmitted to the concrete/steel base in one failure or to the soil around the base in another--or just simply too much wind forces toppling an underdesigned base--I could not tell).

    In most cases, failures are the result of under design (too much stress causing material failure).

    In some cases, pure human error-video (one failure was caused by the erection crew unlocking the transmission with blades set in power producing position instead of feathered, causing the turbine to free run for several days until failure because the electronics (and brakes?) where not yet installed).

    And, there is the UFO caused wind turbine failure (video). ;) Kind of goes to show that failure analysis by youtube/newspapers is pretty questionable. :roll:

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • RCinFLARCinFLA Solar Expert Posts: 1,474 ✭✭✭✭
    Re: Large Windmill collapse in NH

    There might be some relation to power outage. These large windmills are mechanically syncronous to grid with a gear box. A sudden grid load surge may put a tremenous torque spike on the shaft.

    I had a professor in collage that previously worked for G.E. division that built power plant alternators. He said while testing one of the alternators someone accidently put a short on its output that caused it to break loose from its test mount and sent the multi-ton alternator rolling across the factory floor.
  • BB.BB. Super Moderators, Administrators Posts: 32,921 admin
    Re: Large Windmill collapse in NH

    Update from August 2010:

    http://www.syracuse.com/news/index.ssf/2010/08/back_in_action_fenner_turbines.html?mobRedir=false

    Summary, we have no clue what happened, throw more rebar and concrete at design, stand back, turn on.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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