Author Topic: Once again in 3-part (phase) harmony  (Read 19639 times)

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joestue

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Re: Once again in 3-part (phase) harmony
« Reply #33 on: September 29, 2017, 03:42:41 PM »
If you only need a 2.5mH inductor at 15hz when the turbine is putting out 5 amps at 70v, then you dont need to build a 3.1 joule inductor, which would weigh about 20 pounds or more.

A mot core with a dozen turns of 6 gauge wire might work for you. A paper thin airgap, and the core will be saturated at 50 amps.
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kitestrings

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Re: Once again in 3-part (phase) harmony
« Reply #34 on: October 02, 2017, 09:23:37 AM »
Thanks for the responses.  I've done a few things that helped mechanically, and I have several more in mind, but it still makes sense to me that if there's a way to filter out some of the unwanted AC residue from the rectifier output we'd be starting at the likely source of things.  It seems like there must be similar applications where inductive filters are applied without having to build one from scratch.  Unfortunately, I have no feel for scale of the units involved here - a mH isn't readily tangible in the same way as amperage, voltage or mpg might be (for me) - I'd really prefer not to be desiging and building an (and my first) inductor for this task; and adding yet another list of unmeasured variables.

Spar I'll search some of your related archives.  On the mechanical front, it occurred to me that a potential issue could be movement of the coil sectors.  They are held, it part, by sandwiching the stator sectors between a pair of outer polycarbonate rings.  These likely have some flex.  I was considering putting some longer stainless supports in place of washers that might bridge from one to the next; picture like a low-profile piece of framing angle.


I've added rubber isolation to the PVC conduit and various minor things.  it all helps, and over the turbine is working well.  I'd just like to close in on this one detail if at all possible.



joestue

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Re: Once again in 3-part (phase) harmony
« Reply #35 on: October 02, 2017, 04:08:29 PM »
If you place a resistive load on the turbine that closely matches the amps that the turbine pushes into the batteries at the nominal resonance rpm, does the resonance go away?
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SparWeb

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Re: Once again in 3-part (phase) harmony
« Reply #36 on: October 03, 2017, 02:50:49 PM »
Hi KS
I have done the same math as you have, and come up with similar results (turbines working in similar speed ranges etc.)
Just for fun, let me show you the FIRST Google hit I get when I searched for "motor choke size":

https://www.schneider-electric.com/en/product/VW3A4555/line-motor-choke---0.5-mh---60-a---3-phases---94-w---for-variable-speed-drive/

0.5 mH, 3-phase, 60 amps... It weighs 11 kilograms (24 pounds)!
The 2mH version is smaller - about half the weight.

So I'd say your instincts about the inductors are right.

As for the relative vibration of the coil sectors - Hmm I thought you had taken steps to prevent that.  I forget what exactly.
Does the stack of materials in the stator go like this?
-polycarbonate sheet
-Coil
-polycarbonate sheet
-backing ring

If that's correct, is there any sealant between the layers?
Or any other material that prevents vibration?
No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
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kitestrings

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Re: Once again in 3-part (phase) harmony
« Reply #37 on: October 04, 2017, 11:54:04 AM »
Quote
If you place a resistive load on the turbine that closely matches the amps that the turbine pushes into the batteries at the nominal resonance rpm, does the resonance go away?

Hmmm, I'm trying to think how I might be able to do this.  Of course, normally the thing is always tied to the batteries...maybe I could program the load diversion into a matching load, but it would still be in parallel with the batteries.

In light winds, about this speed, I have tried dumping the output into my 3-phase load bank which is similar, but different.  Here we're putting out 300, 400, 500 watts say, and we don't short the 3-phase output, but connect the alternator output via relay to a relatively low resistance 3-phase load.  It brakes the turbine, though less abruptly.

Quote
Does the stack of materials in the stator go like this?
-polycarbonate sheet
-Coil
-polycarbonate sheet
-backing ring

If that's correct, is there any sealant between the layers?
Or any other material that prevents vibration?

Yes, that's right Spar.  There are SS washers against the polycarb. rings, but otherwise you have it.  There is no sealant.  What you are remembering correctly is that we have some movement along the T &G edge over time, and we resolved that by adding a second thru-bolt at every other sector.  This might help:
10828-0
10829-1
10830-2

BTW, I visited a Bergey Excel site yesterday.  It was fairly windy, and the thing had wa- wa-WA-Wavvbbbb rumble at one octave where it shook the wind instruments, and then the EMT conduit violently until the rpms increased.

kitestrings

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Re: Once again in 3-part (phase) harmony
« Reply #38 on: October 04, 2017, 12:00:14 PM »
My apologies to mod.  I didn't grab the re-sized version of one photo.  Doesn't appear to be anything I can fix after the fact.  ~ks

SparWeb

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Re: Once again in 3-part (phase) harmony
« Reply #39 on: October 04, 2017, 03:27:35 PM »
...And I think I can see 2 of these inter-sector bolts in your photo from October 2nd.  Yes I remember that, now.
So this means that out-of-plane motion is still possible, but requires bending of the poly sheet. 
What about the ring around the edge of the stator: are all of those bolts already fastened through the big ring too?
I think I see that in your last (small) photo.  If so, then maybe there isn't much freedom of motion between sectors after all.

I found my isolator bolt picture:
http://www.sparweb.ca/Forum/Turbine_Inspection_lrg.jpg

I was inspired by this arrangement:
http://www.hutchinsonai.com/products/product.cfm?cid=7&fid=35

I'm also interested in seeing what happens if you can try Joe's suggestion. 
No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
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kitestrings

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Re: Once again in 3-part (phase) harmony
« Reply #40 on: October 06, 2017, 09:20:44 AM »
Quote
So this means that out-of-plane motion is still possible, but requires bending of the poly sheet.

Yes, that's right.

It is possible I suppose that the whole stator bracket assembly (SB1 drawing) is flexing, or "ringing" is what I'm envisioning.  It is constructed out of 1/8" SS.  There may be a natural frequency where the the thing shudders.

Nice pic.  I've seen some of those isolation mounts on generators and motor-drives.  Something like this could work on the six (1/2") bolts that mount the bracket assy. to the frame, but it would require taking the thinbg down, disassembly, and a fair amount of work.

I'll try to see if I can load the thing as suggested.  I think I can set the voltage such that we divert to the load a bank in light wind at/about the speed in question.

Thanks for all the suggestions.  ~ks

kitestrings

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Re: Once again in 3-part (phase) harmony
« Reply #41 on: October 06, 2017, 01:55:29 PM »
I could try some of this vibration dampening tape (as ULR point to) on some of the braket surfaces to see if it had any impact.

I also have an aluminum tail-boom and vane (the vane to strut is rubber isolated).  While not the source of vibration, they could be amplifying it.  I think Dan had said he preferred wood veneer for this reason.

kitestrings

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Re: Once again in 3-part (phase) harmony
« Reply #42 on: October 09, 2017, 09:49:12 AM »
I'd written to Hugh P. to see if this was anything that he might have wrangled with -

He responded that it was pretty common, and worst just above cut-in where the ripple is maximum.  He didn't have any simple solution, but shared some work these folks in Greece had been working on:
10839-0
10840-1

but, he also said that the approach "but it saps power and leads to overspeed and only partially reduces the noise.", which seems a lot like the laundry list of side-effects accompanying some new drug.  You can remedy your dry eyes, but you have to live with incontinence, rectal bleeding, memory loss, increased propensity for suicide, etc., etc.

DamonHD

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Re: Once again in 3-part (phase) harmony
« Reply #43 on: October 09, 2017, 10:19:32 AM »
I haven't gone back to the beginning of the thread, but can you just use something a bit gentler than rectifiers straight to the batteries to make the cut in more gentle, eg a crude MPPT tracker?  Or maybe some caps instead somehow to smooth the corners.

Here's an unorthodox thought.  What if you made the rectifiers slightly asymmetrical, eg 2 diodes in series in one of the arms (with one as usual in the others), to spread the full cut-in load slightly.  If that works at all you could then do clever things later to make it more efficient.

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SparWeb

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Re: Once again in 3-part (phase) harmony
« Reply #44 on: October 09, 2017, 11:30:38 AM »
KS,
Have you been following my datalogger thread?

One of the major obstacles to my progress in cleaning up the noise in my WT (yes I admit it still does make noise) is that I haven't been able to accurately measure its speed without leaving an oscilloscope connected to it.  All previous efforts at making a tachometer have been foiled by the harmonic noise.  Which is ironic, since that's the main reason I want to measure it!  The attached picture below is the form at just ONE narrow speed range.  The harmonics shift and change as the speed changes.  Damping the 7th could work between, say, 100-200 RPM but wouldn't matter if the 5th and 11th dominate at other speeds.  Damp ALL the harmonics and 25% of the power gets turned into heat instead of battery charge... then what's the point...

So it's been several years that I've been trying to crack the nut, and now that I do have an accurate and reliable RPM, I can now tell WHICH speeds are the actual noisy ones, rather than just guess and suppose.  Then view the waveform at just THOSE speeds and see if I can do something about just them.

Reliable RPM measurements also opens the door to other experiments, some I've already found will reduce the cut-in noise, by shifting the cut-in speed.  There wasn't much point trying out those things (such as capacitor-bridge triplers, similar but not the same as the linked graphic from Hugh) when my RPM guess was my thumb in the wind.


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, Xantrex C40, DIY 10ft (3m) diameter wind turbine, Tri-Star TS60, 800AH x 24V AGM Battery, Xantrex SW4024
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Mary B

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Re: Once again in 3-part (phase) harmony
« Reply #45 on: October 09, 2017, 07:14:01 PM »
You need to build a low pass filter that cuts off at the maximum frequency the turbine puts out. Schematics on the internet.. http://www.wa4dsy.net/filter/hp_lp_filter.html

kitestrings

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Re: Once again in 3-part (phase) harmony
« Reply #46 on: October 10, 2017, 08:14:30 AM »
One of the challenges, from what I'm reading & understanding, is that these things are operating at comparatively very low frequency.  In your link it says,
Quote
These filters are most effective between 50 kHz and 500 MHz. Below 50 kHz
  Our turbine at cut-in is running only about 12 Hz, and top end - roughly 300 rpm - it still is only about 42 Hz.  A trade off appears to be how much gain is afforded relative to increased losses.  It is likely further complicated by resonance due to the variable speed nature of the thing.

I'm trying to keep in perspective that overall this does not have any effect of performance.  It really is just an annoyance when the wind settles in at a range overlapping the trouble spot.

BTW, below is the source of the paper I referenced above, from Hugh.  The pdf was a bit too large a file, and the best I could do and keep it legible was to carve it up.
10841-0

SparWeb

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Re: Once again in 3-part (phase) harmony
« Reply #47 on: October 10, 2017, 11:02:06 PM »
Thanks Mary.
My low-impedance low-pass filter needs 20mH inductors (2 per phase) to suppress transients 40Hz and above.
It's a lot of copper.
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, Xantrex C40, DIY 10ft (3m) diameter wind turbine, Tri-Star TS60, 800AH x 24V AGM Battery, Xantrex SW4024
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Mary B

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Re: Once again in 3-part (phase) harmony
« Reply #48 on: October 11, 2017, 07:50:59 PM »
Yup the huge coils needed are also inefficient... adds loss

SparWeb

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Re: Once again in 3-part (phase) harmony
« Reply #49 on: October 12, 2017, 01:59:20 AM »
So this is the appeal of the doubler/tripler circuits, silly as they may sound at first.
The point is not to boost the power boost the power boost the power
Actually, if the components are selected carefully, what it CAN do is add a new battery charging circuit but with higher impedance than the main one.  With that circuit in action at speeds below cut-in, the WT is already loaded when the main circuit cut-in is passed.  Why this matters...

To make a mechanical analogy (which isn't such an analogy in this case):
Lightly loaded joints are easily moved by vibration and conduct it to other parts.  Heavily loaded joints do not, because the load and the mass damp out the motions.
Similarly, lightly loaded electrical circuits with low impedance (ie. rectifiers are off) allow transient currents to flow, but these same circuits can damp them out when currents are allowed to flow through loads (ie. rectifiers are on).
ALSO similarly, electrical circuits that have high transient currents experience mechanical vibrations, and those mechanical vibrations are objectionable if the other mechanical loads (weight, thrust and drag) are also low.  That's what's happening at cut-in, too.

So that may be where the doubler/tripler circuits can help.  They put an electrical load on the system where the wasn't before.  Once the main circuit turns on and begins throwing up the transients, the system already has current flowing through the other circuit.  I'm hopeful the mechanical loads in play can damp down the cut-in jiggles.

...and so in theory, a properly selected doubler/tripler could do two good things: increase the trickle of power at low wind speed, and add mechanical damping to the cut-in vibrations.

It's all a beautiful theory in my head...  don't spoil it!
No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
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kitestrings

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Re: Once again in 3-part (phase) harmony
« Reply #50 on: October 18, 2017, 11:55:40 AM »
You reminded me of one thing that I could/should experiment a bit more with - with Classics I can manipulate the power curve to have it load heavier, at lower rpm, or later after more speed is reached.  I tried the latter a bit, with little or no improvement.  Again, where we experience the most noise/shudder is quite a bit above cut-in ~300 watts or so, and about 70V in/ 110 rpm.  We cut-in at ~59V; 92 rpm.

kitestrings

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Re: Once again in 3-part (phase) harmony
« Reply #51 on: December 07, 2017, 02:53:16 PM »
I was up on the tower yesterday in light but steady winds.  One of the elements on our TV antenna had come lose and I could hear it vibrating against the next adjacent one.  Fixed that...

What I also noticed, however, was that the plate or shelf as I think it is called located at the mid-point between the guyed top and the end of the mono-tube was all "abuzz" a certain rpm.  The spec's say it is 12 ga. (7/64") steel, galvanized.  I'd cut, or expanded the factory cut-out so it just fir over the tube... with fours washers and bolts I could cinch to the tube.  I installed over-sized galv. u-bolts with coupler nuts to fasten it to the legs.  The idea was just to take some of the flex form the tube out to the legs at the mid-point where the moment would be highest.  I think it serves this purpose, but I hadn't anticipated the plate just vibrating and vocalizing some of the noise we're going after.

Got to find a way to dampen if anyone has ideas.




JW

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Re: Once again in 3-part (phase) harmony
« Reply #52 on: December 07, 2017, 05:38:48 PM »
We have updated the server and now can attach pictures from a phone or tablet, image files can be much larger that they used to be.

Mary B

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Re: Once again in 3-part (phase) harmony
« Reply #53 on: December 07, 2017, 06:10:16 PM »
Many double up the Rohn 25 rotor shelves and drill holes and weld them together(Use LOTS of ventilation so you don't breathe in galvanizing fumes!). Then re-galvanize the assembly. Takes all the flex out of the shelf. I did that when I had a 10 foot dish on a rohn 25 tower stub 6' tall.

SparWeb

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Re: Once again in 3-part (phase) harmony
« Reply #54 on: December 07, 2017, 09:47:23 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.
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MattM

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Re: Once again in 3-part (phase) harmony
« Reply #55 on: December 07, 2017, 09:57:52 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, 02:07:05 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, 06:32:21 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, 07:35:49 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, 07:39:22 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.
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JW

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Re: Once again in 3-part (phase) harmony
« Reply #60 on: December 08, 2017, 07:45:10 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, 07:45:31 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, Xantrex C40, DIY 10ft (3m) diameter wind turbine, Tri-Star TS60, 800AH x 24V AGM Battery, Xantrex SW4024
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JW

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Re: Once again in 3-part (phase) harmony
« Reply #62 on: December 08, 2017, 07:52:40 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, 08:34:00 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, Xantrex C40, DIY 10ft (3m) diameter wind turbine, Tri-Star TS60, 800AH x 24V AGM Battery, Xantrex SW4024
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MattM

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Re: Once again in 3-part (phase) harmony
« Reply #64 on: December 09, 2017, 08:49:09 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, 09:45:23 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