We're having a windy day. The Eco-Cottage wind turbine was whipping around so fast, Sara came in to warn me in case something was wrong. The blades had set up a nasty reverberation that set in at the highest RPM, about 1-2% of the time, but very noticeable. This has never happened before, but we know we dinged up the mild steel blade hub when we dropped it recently, so they are probably out of alignment. But the RPMs were still not above the rated RPM for the original bearings. This is a vehicular alternator retrofitted with a permanent magnet. The bearings are good up to vehicular-type RPM, upwards of several thousand. It's almost impossible to reach those RPMs just with the wind. And it doesn't really start producing until about a 15 MPH wind speed. Not completely indestructible, but very tough.
In a sense, the engineering is such that the turbine doesn't produce it's maximum rated power output until the wind is going at 50 MPH or more. Which is good, because it will last a long time. The tower has guy lines, and they were doing their job fine, coming tight and loose as the wind shifted like the shroud lines on a sloop.
All in all, I think trading power for indestructibility is a fairly good idea if you want to install a wind turbine next to a student dorm.
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2 comments:
Mick, you might want to ask Sara, or Peter about that indestructibility thing.
Ah well. See my latest post:)
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