Author Topic: Once again in 3-part (phase) harmony  (Read 10332 times)

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SparWeb

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Re: Once again in 3-part (phase) harmony
« Reply #54 on: December 07, 2017, 07:47:23 PM »
While you were up there, did you happen to check that all the fasteners were tight?
U-bolts (as you probably know) are very flexible fasteners, which allow motion before they take up any load.
Did you use self-locking nuts?  Given your other work, probably so, but I thought I'd ask...

What kind of collar do you have on the tube - presumably the collar was supplied with the plate?
I have a DMX tower which is a similar design, but I had to make my own collar for the extension tube.
No one believes the theory except the one who developed it.  Everyone believes the experiment except the one who ran it.

System spec: 135w BP multicrystalline panels, regulated by Xantrex C40, DIY 8ft diameter wind turbine, regulated by Tri-Star TS60, 800AH x 24V AGM Battery, Xantrex SW4024

MattM

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Re: Once again in 3-part (phase) harmony
« Reply #55 on: December 07, 2017, 07:57:52 PM »
If you double them up by stacking one upside down, you should be able to add plates to tie each pair of U-bolts together.  That should make welding unnecessary as welding on galvanized steel is foolish.  Anyone that suggests it's okay is not aware how toxic the fumes can be and probably never tried it.  Listen to Mary's warnings and please do not weld galvanized.  I know a fellow that did it unaware and died miserably a few weeks later leaving behind his young children, one with special needs.

kitestrings

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Re: Once again in 3-part (phase) harmony
« Reply #56 on: December 08, 2017, 12:07:05 PM »
Thanks for the replies.  Ideally I'd like to see if I can find a solution that can be done on the tower.  It's not out of the question that a second plate could be added, but the easier fix would be if it could be a bolt-on support.  I was thinking perhaps angle-iron perhaps with dampening spacers.  I also was thinking that an option might be to use neoprene bumpers (with a steel core) mounted to the plate with a angle or flat-stock stiffener.

Quote
While you were up there, did you happen to check that all the fasteners were tight?
U-bolts (as you probably know) are very flexible fasteners, which allow motion before they take up any load.
Did you use self-locking nuts?

I'll check some more when the winds are gone.  I was pretty close to a moving rotor, but it was helpful to witness this - there was nothing obviously lose.

Yes, I used over-sized galv coupler nuts and u-bolts and then added jamb-nuts on each coupler nut.  This is the lower set, which is much heavier, but the leg connection is similar...in hind-sight (which is sooo much more observant) I should've just used two of these:
10953-0

Mary B

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Re: Once again in 3-part (phase) harmony
« Reply #57 on: December 08, 2017, 04:32:21 PM »
You CAN weld galvanized material safely, I helped the local welder and we did it quite often on farm equiipment. 2 fans blowing fumes out the door, door open even if it was -20f outside so lots of fresh air... I have never heard of the fumes killing anyone but they can sure make you feel like death!


If you double them up by stacking one upside down, you should be able to add plates to tie each pair of U-bolts together.  That should make welding unnecessary as welding on galvanized steel is foolish.  Anyone that suggests it's okay is not aware how toxic the fumes can be and probably never tried it.  Listen to Mary's warnings and please do not weld galvanized.  I know a fellow that did it unaware and died miserably a few weeks later leaving behind his young children, one with special needs.

JW

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Re: Once again in 3-part (phase) harmony
« Reply #58 on: December 08, 2017, 05:35:49 PM »
I just made an adjustment to image display resolution, and larger images will still display.

SparWeb

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Re: Once again in 3-part (phase) harmony
« Reply #59 on: December 08, 2017, 05:39:22 PM »
Thanks JW,
Those pictures make me dizzy now.
No one believes the theory except the one who developed it.  Everyone believes the experiment except the one who ran it.

System spec: 135w BP multicrystalline panels, regulated by Xantrex C40, DIY 8ft diameter wind turbine, regulated by Tri-Star TS60, 800AH x 24V AGM Battery, Xantrex SW4024

JW

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Re: Once again in 3-part (phase) harmony
« Reply #60 on: December 08, 2017, 05:45:10 PM »
I set the display resolution to the same as facebook

SparWeb

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Re: Once again in 3-part (phase) harmony
« Reply #61 on: December 08, 2017, 05:45:31 PM »
Or Maybe it's the zinc fumes....
No one believes the theory except the one who developed it.  Everyone believes the experiment except the one who ran it.

System spec: 135w BP multicrystalline panels, regulated by Xantrex C40, DIY 8ft diameter wind turbine, regulated by Tri-Star TS60, 800AH x 24V AGM Battery, Xantrex SW4024

JW

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Re: Once again in 3-part (phase) harmony
« Reply #62 on: December 08, 2017, 05:52:40 PM »
:)

I did some tig welding on a Briggs and Stratton cyl head and it smelled like onions. On of the more experienced welders around me, said hey watch out for that the alloy is making poison gas.

Galvanized coated steel is easy to grind before welding and you get a better weld. 

SparWeb

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Re: Once again in 3-part (phase) harmony
« Reply #63 on: December 08, 2017, 06:34:00 PM »
That mast support is nothing like the sheet-metal plate pictured above.  I'm not ready to believe that a heavy mast anchor fitting like that could just wobble around making noise unless the bolts are loose somewhere.  If you've checked the fasteners, and still hearing a noise, then something else is moving and this plate is just part of the path.  Rather than speculate more about the source of the noise, here's something to consider:



https://play.google.com/store/apps/details?id=com.nfx.specscope

If that's not fancy enough for you:



https://play.google.com/store/apps/details?id=com.keuwl.spectrumanalyzer

Not that I know if you have an Android phone or an iPhone, but if dozens of examples like this exists for my android phone then you should be able to find an equivalent in iPhone, if that's what you have.  It's pretty amazing when you find high quality software like this.  For free!
I installed these on my phone, and I've found them surprisingly useful and interesting to use.  I have watched it measure the engine RPM's change in my car, and on an airplane.  I have monitored the vibrations in my own tower with it, too.

Next time you climb up, run the app and point the microphone at various locations to "sniff out" the source of the noise.

No one believes the theory except the one who developed it.  Everyone believes the experiment except the one who ran it.

System spec: 135w BP multicrystalline panels, regulated by Xantrex C40, DIY 8ft diameter wind turbine, regulated by Tri-Star TS60, 800AH x 24V AGM Battery, Xantrex SW4024

MattM

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Re: Once again in 3-part (phase) harmony
« Reply #64 on: December 09, 2017, 06:49:09 PM »
Quarter inch supporting 5 HP motors get enough flex to oscillate things nearby, there is absolutely nothing to suggest the plate would not be prone to the same.  Steel is many characteristics, elastic being one.  Regardless if the plate is a quarter or an inch or a foot in thickness, it has the same elasticity.  Flexibility isn't steel's only trait.  And nothing suggests and nobody specifically implied the vibration originated from the turbine.  The waves may be traveling in three dimensions up and down the mast.  Temperature changes and all sorts of environmental inputs can create the vibration.

kitestrings

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Re: Once again in 3-part (phase) harmony
« Reply #65 on: December 11, 2017, 07:45:23 AM »
Quote
That mast support is nothing like the sheet-metal plate pictured above.

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.

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And nothing suggests and nobody specifically implied the vibration originated from the turbine.

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

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Re: Once again in 3-part (phase) harmony
« Reply #66 on: December 11, 2017, 03:46:32 PM »
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

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Re: Once again in 3-part (phase) harmony
« Reply #67 on: December 11, 2017, 06:32:17 PM »
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.