tower vibration [RE-wrenches]

[Bob Ellison]

Kirk,
Pull the blades and get them weighed, the post office scale actually works
well and they have a sense of humor about it...
You are looking for differences in blade weights. It does not take much.
Another thing with the 1500's is the bolt in the furl pivot bushing needs to
be longer, it is short enough that the threads are in the bushing and eat
the bushing alive. Use a longer bolt. Another failure I have seen is the
shaft breaking in the stator, the retrofit uses 3 bearing. You can't check
this with the magnet can on, it probably needs to come off, there is not
much motion but it will move around a little. 

I have the balancing procedure if you need it. Write the weight on each
blade so you can keep track.

Later,
Bob

-----Original Message-----
From: Kirk Herander [mailto:kirk at vtsolar.com] 
Sent: Tuesday, April 25, 2006 7:44 PM
To: RE-wrenches at topica.com
Subject: tower vibration [RE-wrenches]



Hello,
 
I have an old World Power H1500 (1500 watt) machine on an 80' homebrew
sectional steel pipe tower. It's in a high wind area, and has flown with no
complaints for 7 + years. Several months ago, the tower started to vibrate
in high winds, maybe 15 + MPH, when the machine really starts cooking. I
lowered the tower expecting to find something obvious - but no luck. The
blades are on tight, the tail boom pivot bolt/bearings look fine, all bolts
are tight, no problems with the machine that I can see.
When the tower is up and brake on, there is the normal several inches of
deflection on all guys. But at those higher wind speeds the front and rear
middle and top guys develop at least a foot of "up and down"
deflection - it really looks scary - and the tower shakes big time. What am
I missing? 
Could the guys be too tight? Or too loose? Thanks.
 
Kirk Herander
Vermont Solar Engineering
802.863.1202
fax 802.863-7908
NABCEP(tm) Certified Solar PV Installer
Xantrex Certified Dealer Charter Member
NYSERDA-eligible installer
VT Solar and Wind Partner
 

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