Homebrewed Electricity > Wind

Once again in 3-part (phase) harmony

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kitestrings:

--- Quote ---That mast support is nothing like the sheet-metal plate pictured above.
--- End quote ---

That's right Spar, the lower plate is much heavier, sorry for the confusion.  It is the mid-plate that is my adapted use of the 25G R-AS25G.  I believe there is a resonant frequency ~110-115 rpm where this light gauge plate vibrates/buzzes.  A don't believe there is anything loose, but I certainly will be checking.


--- Quote ---And nothing suggests and nobody specifically implied the vibration originated from the turbine.
--- End quote ---

Matt, I think the turbine is the source here, as it only does this when we get a bit above cut-in ~300 watts or so, and about 70V in/ 110 rpm.  I believe it is this clipping ripple discussed earlier, but I think the augmentation thru this plate can be mitigated.

~ks

Mary B:
You could bolt an angle iron bracket across the bottom of the plate. If it is the source of the vibration it would change the frequency. But I suspect you are hearing the tower legs vibrate. My house brackets Rohn 25 antenna tower makes a heck of a racket in high winds as it vibrates.

MattM:
I remember the location of guy wires playing a big role in vibration.

SparWeb's suggestions would help diagnose the source of you could record wind speed, too.  Each rotation of the turbine disrupts airflow each time the blade passes in front of the mast.  An out of balance turbine would have a similar frequency, but a different trough pattern. Sound forms might suggest something altogether out of sync with the turbine. Knowing the frequency would pinpoint more specifically the type of vibration.  It could be something as simple as a broken  allowing tangential rotation of an isolated segment of the tower.

kitestrings:
I haven't been able to follow up on this - most of the fixes are best in summer weather anyway...

A curious thing though... we had a freezing rain, sleet, snow event late last week.  Temp's were at record highs ~50 degF Friday, and then back to -10F last night.  The blades, tower, mount all had a thin frozen layer of ice, but I started the turbine on Saturday morning.  It had been lulling about, so there didn't seem to be any imbalance.  The output was a bit diminished I'd say, but the blade whistle was totally gone!  And, the plate vibration was also negligible.

On Sunday I scampered up to look it over.  The plate and tube were sort of welded together with a seal of ice.  The blades had a smooth, but irregular coating.  There was virtually none on the leading edge, heavier near the thickest cord section; spottier on the trailing edge.  (Should've had my camera).

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