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1
Wind / Re: axial generator with lamination core
« Last post by JW on Today at 07:03:28 PM »
BRANDNEWB...

you must understand I am a Process Engineer, when I see mbouwer's work I see an expert. This guy even makes his own steel castings.

Im often impressed with his fabrication ability. It obvious you have have not looked at all the projects he has Built.

I often remark how comprehensive the database is on the site here. I recently was snapped at by another user for pulling up an old thread. My point was not start posting agian BUT if you saw the thread and read thru it from top to bottom you would see the issues solved there.

There are weath of threads that address the issues that your are bringing up.

You need to do more research and less postulating on your replys. I have been building this site for over 20 years, I have read all of the database as it was crated.

Your going to have to search for old threads witch explian your questions...

I am hesitant to point out threads of relevance to your issues, BUT THEY EXIST.

YOU NEED TO CHANCE YOU MOTISOPEREMDI :)

Quote
The term "modus operandi" is a Latin term that describes an individual or group's habitual way of operating, which represents a discernible pattern. A modus operandi (commonly abbreviated as "M.O.") is mainly used to discuss criminal behavior and is often used by professionals to prevent future crimes.

JW
2
Wind / Re: axial generator with lamination core
« Last post by brandnewb on Today at 04:25:59 PM »
May I please ask why not only the blades have changed but seemingly the whole setup and the situation it is in.

Look brother I wish that I am mistaken but it seems so implausible.

If you are that far along with a small DC motor then please just make us a HD video of the turbine spinning and what it is producing and then I will host it for you if you like me do not want to use youtube.

{1}the more I look at it the more it all seem like the same turbine. But the real question remains.{/1}

Quote from: mbouwer on May 30, 2024, 04:50:25 AM
(Attachment Link)

The blade adjustment has been installed and I can now set the rotor revolutions manually.
3
Wind / Re: axial generator with lamination core
« Last post by mbouwer on Today at 10:14:56 AM »
The Nordex model with 2 m diameter blades in combination with the small generator can provide enough output to power the control and regulate the speed ( 20 rpm ) due to the blade adjustment.

Attachments: verhouding molen en generator.jpg * verhouding molen en generator.jpg

4
Heating / Re: Optimising domestic space-heating retrofits from nat gas to heat pump
« Last post by DamonHD on Today at 03:22:58 AM »
Yesterday my first formal paper hit whatever the academic equivalent of the news stand is:

https://www.mdpi.com/2071-1050/16/11/4710

Domestic heating systems across northern Europe are responsible for a substantial fraction of their countries’ carbon footprints. In the UK, the vast majority of home space heating is via natural gas boilers with 'wet' hydronic radiator systems. Most of those use TRVs (thermostatic radiator valves) for micro-zoning, to avoid overheating, improve comfort and save energy. To meet Net Zero targets, 20 million such UK gas systems may be retrofitted with heat pumps. Heat pump system designers and installers are cautious about retaining TRVs in such systems in part because of worries that TRV temperature setbacks that lower heat demand may raise heat pump electricity demand in a "bad setback effect", thus wasting energy. This paper presents a new view of heat pump control and provides the first exploration of this issue through the development of a simple physics-based model. The model tests an installation industry claim about the negative effect of TRVs, and finds that though real it should not apply to typical UK retrofits with weather compensation. The energy efficiency benefits of TRVs for older and partly occupied homes, and to keep bedrooms cooler, remain valid. Comfort-seeking householders and installers should know that setting 'stiff' temperature regulation may invoke the bad setback effect and cost dearly in energy and carbon footprint.

Rgds

Damon
5
Wind / Re: axial generator with lamination core
« Last post by mbouwer on May 31, 2024, 03:33:24 AM »
Now the rotor starts turning at the slightest wind.
6
Wind / Re: axial generator with lamination core
« Last post by Bruce S on May 30, 2024, 08:46:47 AM »
Nice!
At what wind speed do the blades start to turn?

Cheers
Bruce S
7
Wind / Re: axial generator with lamination core
« Last post by mbouwer on May 30, 2024, 04:50:25 AM »


The blade adjustment has been installed and I can now set the rotor revolutions manually.

Attachments: model...JPG * model...JPG

8
Wind / Re: axial generator with lamination core
« Last post by mbouwer on May 29, 2024, 08:46:26 AM »
It is the Kitestrings design and a great source of inspiration.

Attachments: kitestrings..jpg * kitestrings..jpg

9
Wind / Re: axial generator with lamination core
« Last post by Bruce S on May 29, 2024, 08:27:29 AM »
Cool looking tail on the one in the pic.
I wonder where you got the inspiration from  ;D.

Cheers
Bruce S
10
Wind / Re: axial generator with lamination core
« Last post by mbouwer on May 29, 2024, 03:58:18 AM »
You are so right, but it is about our search for how we as self-builders also can get a nice workpiece in the garden:
a safe, reliable, not too difficult to build, small windmill to generate (part of) our required electricity.

Attachments: kitestrings.jpg * kitestrings.jpg

11
Wind / Re: H-Darreius wind turbines ( VAWT ) !
« Last post by topspeed on May 28, 2024, 06:26:08 PM »
Quote from: Bruce S on May 28, 2024, 04:58:28 PM
Reminds me of a Hammer Head .
How are you going to going to study the currents? Smoke machine?

Bruce S

Just by looking at the shark below. ;D
12
Wind / Re: H-Darreius wind turbines ( VAWT ) !
« Last post by Bruce S on May 28, 2024, 04:58:28 PM »
Reminds me of a Hammer Head .
How are you going to going to study the currents? Smoke machine?

Bruce S
13
Wind / Re: H-Darreius wind turbines ( VAWT ) !
« Last post by topspeed on May 28, 2024, 03:07:12 PM »
Hahhaaa...it is shark vane to study the currents under the cycloturbine.

This black box is to control the system. It has even a wattmeter...rectifier...fuses... switches...and emergency cut off.


15945-0

Attachments: läppä2.jpg * läppä2.jpg

14
Wind / Re: axial generator with lamination core
« Last post by kitestrings on May 28, 2024, 02:52:35 PM »
mbouwer,

I've enjoyed seeing your craftsmanship, components and creativity, so by no means do I wish to discourage you, but I have to agree with Adriaaan on this one.  We've had this discussion in the past, and in this same post IIRC, but to me this is just adding way more complexity than required.  With each component and moving part comes added points of maintenance and potential failure.

For large scale turbines, and wind farms, it may make more sense.  Here, there may be a crane on site, and with preventative maintenance scheduled at regular intervals the added incremental benefits may make sense.  For small-scale wind, I prefer a simpler approach with the least number of moving parts up on the tower.

Best, ~ks
15
Wind / Re: axial generator with lamination core
« Last post by Adriaan Kragten on May 28, 2024, 07:12:21 AM »
Quote from: mbouwer on May 28, 2024, 04:33:59 AM
Conclusion: for DIY construction it is best to make a small axial generator with a simple accelerating transmission between the main shaft and the generator.

(Attachment Link)

That would not be my conclusion and I think of many others on this forum as I see how many members are making direct drive generators. For big wind turbines, direct drive can be questioned but for small wind turbines, direct drive is almost always the best choice. I think that a transmission can only be justified if you can buy the generator and the transmission as one unit for a low price. But you should not be supprised if the transmission has a short lifetime or if the transmission results in a large friction torque a zero rpm. The unit which you showed in the photo has probably a DC-motor with brushes. The friction torque of the brushes is multiplied by the gear ratio as a large friction torque on the slow shaft of the gear box.
16
Wind / Re: axial generator with lamination core
« Last post by mbouwer on May 28, 2024, 04:33:59 AM »
Conclusion: for DIY construction it is best to make a small axial generator with a simple accelerating transmission between the main shaft and the generator.

Attachments: as en naaf 9-12.JPG * as en naaf 9-12.JPG

17
Wind / Re: H-Darreius wind turbines ( VAWT ) !
« Last post by brandnewb on May 27, 2024, 10:48:52 AM »
yes a test rig :) . if one does not employ one then one is probably an artisan. or foolhardy :)

Quote from: topspeed on May 20, 2024, 04:47:24 AM
My new electrical part of the test rig.

(Attachment Link)

(Attachment Link)

I have not been able to make the new blades yet. I have been able to find and correct several weak points in the old set up.
18
Wind / Re: H-Darreius wind turbines ( VAWT ) !
« Last post by brandnewb on May 27, 2024, 10:43:25 AM »
scale wise this looks massive!. and what is it even? full steel but with a black lacker of sorts?

I am well impressed and given the the size of the holes you have left for connections I am thinking things will not fly off any time soon.

Anyway what is your intended operation range in terms of RPM of the blades and RPM of the PMA and such?

Quote from: topspeed on May 20, 2024, 04:47:24 AM
My new electrical part of the test rig.

(Attachment Link)

(Attachment Link)

I have not been able to make the new blades yet. I have been able to find and correct several weak points in the old set up.
19
Wind / Re: H-Darreius wind turbines ( VAWT ) !
« Last post by topspeed on May 26, 2024, 02:29:16 PM »
Wind vane added to study the cyclic current under the swept area.

15943-0

Attachments: sillivasarahai_tiikeriraitainen.jpg * sillivasarahai_tiikeriraitainen.jpg

20
Wind / Re: axial generator with lamination core
« Last post by Adriaan Kragten on May 26, 2024, 03:07:16 AM »
Quote from: JW on May 25, 2024, 10:59:22 AM
Brandnewb



Notice the mention of a planetary gearset.

The trick is to getting the desired output in watts.

This is where Thermodynamics comes into play. The amount of heat in the conductors is acceptable for the expected power output.

Small alternators are also useful.

JW

 

I doubt if this conclusion is true without having made detailed calculations for both options.
 
The main advantage of an increasing gear ratio in between rotor and generator is that the generator runs at a much higher rotational speed and therefore a much lower torque level is needed to get the same mechanical power level. So the generator is much lighter and much cheaper. However, the costs of the transmission have to be added. The main advantage of a direct drive generator is that it has no gear box which needs lubrication, will wear or can even break down, makes noice and has its own efficiency and its own friction torque. However, a direct drive generator is heavier and more expensive.

If the efficiency of both generators are the same, the dissipation of the heat is much easier for a direct drive generator than for a geared generator as a direct drive generator has a much larger area. In the beginning of the development of big wind turbines, all of them used an accellerating gearing in between rotor and generator. But starting with Enercon, direct drive generators are now also used for big wind turbines of other manufacture. The disadvantage that the generator is more expensive is compensated by the fact that no transmission means no maintenance, no noice, no extra friction torque because of gear wheels and more bearings and seals and no risk of failure.
21
Wind / Re: axial generator with lamination core
« Last post by JW on May 25, 2024, 10:59:22 AM »
Brandnewb



Notice the mention of a planetary gearset.

The trick is to getting the desired output in watts.

This is where Thermodynamics comes into play. The amount of heat in the conductors is acceptable for the expected power output.

Small alternators are also useful.

You have to understand the balance of all components on any gen-system.

I see your thinking outside the box, and that's fine. You need to understand the harmony of your intended system goals.

I am a Process Engineer people ask me what's that? Its a type of "systems technology" for example front the base of your structure, branches it to other types of systems that are interacting with each other.

JW

 


22
Wind / Re: axial generator with lamination core
« Last post by mbouwer on May 25, 2024, 03:55:51 AM »
The intention is that I make a working model of a Nordex.
A windmill friend is going to add the controls.

Attachments: control components.jpg * control components.jpg

23
Wind / Re: axial generator with lamination core
« Last post by brandnewb on May 24, 2024, 08:17:07 AM »
Please allow me to potentially ask about something I could have already known would I have studied the whole thread.

Please tell us your expectations. what is the goal.

One thing for sure is that you have mad skills! far beyond mine. no question.

But what is the intend?

If I look at your latest image. Unless the scale if unclear it looks like a small dc motor of some kind.

Anyway. If your intend is small scale then sure keep at it as I think you know full well how to craftsmen stuff. I still look up to you regarding that!.

If your intend is aimed a little higher, like where my crosshairs are, than we should seriously have a sit down together to compare plans. I want to warn you for possible disappointments ahead in that case.
24
Wind / Re: axial generator with lamination core
« Last post by mbouwer on May 24, 2024, 05:33:02 AM »
This small generator with planetary gearbox fits well in the model.

Attachments: kleine generator.JPG * kleine generator.JPG

25
Wind / Re: axial generator with lamination core
« Last post by mbouwer on May 24, 2024, 05:25:04 AM »


The shape of the blades is not optimal, but for the model I only want them to rotate about 20 revolutions.

Attachments: wieken voor model.JPG * wieken voor model.JPG

26
Wind / Re: axial generator with lamination core
« Last post by mbouwer on May 24, 2024, 05:06:07 AM »


This is the Nordex that I want to make a working model of.

Attachments: Nordex.jpg * Nordex.jpg

27
Logged in diaries / Re: VAWT backyard experiements
« Last post by Mary B on May 23, 2024, 11:07:15 AM »
Quote from: brandnewb on May 21, 2024, 09:36:40 AM
Quote from: electrondady1 on May 20, 2024, 09:45:28 AM
That's a great spot for you mill.
How much space will you put between the ground and the bottom of the rotating body ?

That depends.

The rotating body might be dig in so no no longer require guy wires.

But My eventual goal is to have the arms rotate close to the ground/structure that holds them.
So we can have them floating if all is engineered out enough.

But in direct answer to your question in this specific scenario it is a little more than 120CM above grass level.

---

Even though that the rotating body does still spin on the grass at like 10 CM elevation.

Hence my idea to dig them in or submerge them somehow. These columns

But in the end of the day the level of the arms should be situational. For me it is as high so long they to not cut my other projects.


#2
Quote from: electrondady1 on May 20, 2024, 09:45:28 AM
That's a great spot for you mill.
How much space will you put between the ground and the bottom of the rotating body ?

I would like to debate what is the difference between a mill and a turbine?

I think I know. Please let me know if I am mistaken.

A mill is a wind/ water turbine driven machine that mills something. usually grain or the likes.

Hence we are no longer milling anything I think we should be able to call it turbines yes?

Or at the very least chargers(of batteries)

Please just accept my emotional response because I feel about these things. As my country "invented" mills (that is probably not true at all)
So I just am a bit of a strickler regarding that. :(


#3
Quote from: MattM on May 20, 2024, 08:04:14 AM
Lawn mowers have used a magnetic clutch system for decades.  Your answer to torque at a certain point might use a similar method to kick in a bigger load or to brake.

Yes brother, I have no idea what you meant there. Please elaborate and I will be sure to do the same.


#4
Please let me get this out there!!

Should anyone know how to create a 1:30 drive. then please do not be shy..

I can maybe get to 22, even more perhaps 24 x!! and that is including knowing that the drive will become the weak point and break down rather fast!!!

1:30 stable? any ideas gang?

Structure that can take a beating, is not very large(12" on a face) and only 5' tall. Has held a 9 square meter wind load with no problem. Available commercially all over the world and used 10' pieces can be found for $75 in good shape, $50 with a bend at one end(so cut it off! You don't need a 10' tall support!). Called Rohn 25g tower. Will handle your VAWT no problem when set in a block of concrete 4x4x4 foot square. Mine is set on angle iron legs that are in the concrete so water can drain from the legs and not freeze in winter, or rot the legs with rust in summer. If setting in concrete the bottom 2" of the legs must be set in gravel then concrete poured around the rest.

The dish antenna that was on this folded in half in a 100mph wind gust... tower section suffered zero damage!

28
Logged in diaries / Re: VAWT backyard experiements
« Last post by brandnewb on May 23, 2024, 07:52:08 AM »
so it takes about 350 grams of force/power/input or what ever we call it to get the turbine spinning from a stand still.

I am not sure what that means but it does mean there are losses. and a lot of them :(

The cups are up again and now we wait for the wind to pick up.

drumm rolllls
29
Wind / Re: axial generator with lamination core
« Last post by Adriaan Kragten on May 23, 2024, 02:26:48 AM »
Something more about ways to prevent a large peak on the cogging torque. If the housing of an asynchronous motor is used for a radial flux PM-generator, there are several ways to prevent cogging. One way is to use two less or two more armature poles than stator poles and to use a 1-layer winding with coils around only one stator pole. This methode is described in my reports KD 560, KD 624 and KD 648. Another way, for which the standard winding of a 4-pole motor, a 6-pole motor or an 8-pole motor can be used, is described in reports KD 730, KD 747 and KD 760.
30
Wind / Re: axial generator with lamination core
« Last post by Adriaan Kragten on May 23, 2024, 02:08:24 AM »
Quote from: brandnewb on May 22, 2024, 11:00:29 AM
are we sure that a 2m rotor diam is going to be useful?

Adriaan do you concur?

If so then I think we should all be updated on a new way of calculating as then it seems that this omincalcularor I refereed to is useless.

It all depends on the Cp of the rotor and on how much mechanical power P you want at which wind speed, what rotor diameter is required (see KD 35 formula 4.1 and 7.10). It depends on the efficiency of the generator and the efficiency of the transmission which electrical power you get (see KD 35 formula 4.2). So it is possible to design an effective wind turbine with a rotor diameter of 2 m but you must know what you are doing and realise an good matching in between rotor and generator (see KD 35 chapter8) and use a proper safety system (see KD 485). If you don't understand all the theory, you can build one of my small VIRYA designs specified at the menu VIRYA folders on my website. Report KD 35 is available in English and in Dutch at the menu KD-reports on my website: www.kdwindturbines.nl.
31
Wind / Re: Block diagram for our turbine
« Last post by kitestrings on May 22, 2024, 11:58:40 AM »
"...supplemented by wood atm."  I'm not sure what this is?  Can you explain.

For lighting, I always thought it'd be interesting to experiment with fiber optics.  It's well out of my area of expertise, and likely not practical, but the concept of routing light directly into a space with minimal penetrations through the envelope is interesting.  Although if, I assume, it has to be supplemented with artificial light, it may not be worth the duplication of sources.  I guess if a natural light-box/collector could be centrally supported...
32
Wind / Re: axial generator with lamination core
« Last post by brandnewb on May 22, 2024, 11:00:29 AM »
are we sure that a 2m rotor diam is going to be useful?

Adriaan do you concur?

If so then I think we should all be updated on a new way of calculating as then it seems that this omincalcularor I refereed to is useless.
33
Wind / Re: Block diagram for our turbine
« Last post by XeonPony on May 22, 2024, 08:30:32 AM »
Quote from: SparWeb on February 24, 2024, 02:54:38 PM
Quote
more than you asked for.
Sure, every system that evolves long enough develops prehensile things like gall bladders and wisdom teeth.

I was pretty sure you operated off-grid, but wondered if there was occasional support from an existing supply.

Thanks for the extra detail.

My house is already on grid, so I'm looking at an existing pump, stove, heating and other things that pull many thousands of kW each.  And it's trivially easy to turn them all on at the same time.  Replacing them all would be very invasive surgery.  While I could save energy that way, I also expect such changes would not increase the value of the house, nor have anything but a negative effect on reliability or ease of repair.  For all of the modifications I've already done, I'm the only repair man.  I've whittled our consumption down to less than 8000 kWhr per year.  Probably terrible to an off-gridder like you.

These considerations make choosing a grid-tie inverter pretty complicated.

My average use for a day (24h) is apxly 6KwH to 7KwH, I turn the hot water tank on as I need it, usually Wednesday, Sunday to shower do laundry

Heating is mainly diesel supplemented by wood atm

Lights, LED and really only use them in 2 rooms, rest is natural light

Future plan will be to use a boiler to dump any excess wind energy into and put a 30 tube solar thermal tube onto it as well, easier to shed heat during summer by utilizing shading methods, as I intend to use some heat to warm a methane digested.
34
Wind / Re: H-Darreius wind turbines ( VAWT ) !
« Last post by topspeed on May 22, 2024, 06:26:40 AM »
This displays the colors of the 2. prototype that has been been the most successful so far.

It has inside:

1. kill switch
2. main switch
3. rectifier
4. fuses
5. watt meter

15938-0

Attachments: 5.jpg * 5.jpg

35
Wind / Re: axial generator with lamination core
« Last post by mbouwer on May 22, 2024, 05:19:31 AM »
Back to the blade adjustment in the spinner of the Nordex model.

Attachments: inside spinner.JPG * inside spinner.JPG

36
Wind / Re: Christmas Windmill Time
« Last post by taylorp035 on May 21, 2024, 08:45:48 PM »
Finished the 2 part epoxy for the coils.  Also completed the new jacking screw system.  Eventually I'll have to take a picture of that once finally assembled since I think you guys will like it.

Measured the final thickness at 0.406", so that will be a large improvement for the magnetic flux versus the ~0.700-0.800" I had on the last one.

15936-0

Attachments: PXL_20240522_001456763.jpg * PXL_20240522_001456763.jpg

37
Wind / Re: axial generator with lamination core
« Last post by brandnewb on May 21, 2024, 05:20:37 PM »
Quote from: mbouwer on May 19, 2024, 04:51:10 AM
@ Brandnewb,

Our government is increasingly positive about wind energy.

Wicked!

I had never understood that any government was able to influence the power potential of a given wing span.!

But I am always humble.
38
Wind / Re: axial generator with lamination core
« Last post by brandnewb on May 21, 2024, 05:13:44 PM »
Dear Adriaan,

You know I have you in the highest of regards!!

I realize I am still not hibernating :( even thouh I said I would and I should yes agreed.

Please make sense of it all. what is wrong, other than build ability, with my current setup of the PMA?
39
User Diaries / Re: pigeons
« Last post by XeonPony on May 21, 2024, 03:55:45 PM »
Quote from: TechAdmin on May 20, 2024, 10:34:17 AM
Big issue in my city everywhere... Mary got it right, spikes are the only viable solution.
... Or a rifle ;D

Bagged 50 for some one once, I got tired before I could get them all!
40
User Diaries / Re: pigeons
« Last post by XeonPony on May 21, 2024, 03:54:11 PM »
CCI Fragmenting quiets.

As loud as an air rifle, won't penetrate the fender of a car, but removes magpies and crows and pigeons very effectively!

https://www.cci-ammunition.com/rimfire/cci/quiet-22-segmented-hp/6-970.html
41
Wind / Re: axial generator with lamination core
« Last post by brandnewb on May 21, 2024, 10:58:44 AM »
I think only skilled people can use create coil enhanced coils.

I for one am not one of them yet.

I know that having the cores enhanced will result in more ability to exact power from the wind via the the PMA.

Yet it will also introduce facts like;

"Ok boy, can you build something strong enough?"

hahah I still can not :(

So I focus on the DIY aspects.. is it at al conceivable that one can build this? That is DIY!!

Truth be told though that I am starting to0 lean towards outsourcing to machining shops.

I do not want to do it. and doing so will mean the biggest fail in history.
Yet I am considering!!
42
Logged in diaries / Re: VAWT backyard experiements
« Last post by brandnewb on May 21, 2024, 09:36:40 AM »
Quote from: electrondady1 on May 20, 2024, 09:45:28 AM
That's a great spot for you mill.
How much space will you put between the ground and the bottom of the rotating body ?

That depends.

The rotating body might be dig in so no no longer require guy wires.

But My eventual goal is to have the arms rotate close to the ground/structure that holds them.
So we can have them floating if all is engineered out enough.

But in direct answer to your question in this specific scenario it is a little more than 120CM above grass level.

---

Even though that the rotating body does still spin on the grass at like 10 CM elevation.

Hence my idea to dig them in or submerge them somehow. These columns

But in the end of the day the level of the arms should be situational. For me it is as high so long they to not cut my other projects.


#2
Quote from: electrondady1 on May 20, 2024, 09:45:28 AM
That's a great spot for you mill.
How much space will you put between the ground and the bottom of the rotating body ?

I would like to debate what is the difference between a mill and a turbine?

I think I know. Please let me know if I am mistaken.

A mill is a wind/ water turbine driven machine that mills something. usually grain or the likes.

Hence we are no longer milling anything I think we should be able to call it turbines yes?

Or at the very least chargers(of batteries)

Please just accept my emotional response because I feel about these things. As my country "invented" mills (that is probably not true at all)
So I just am a bit of a strickler regarding that. :(


#3
Quote from: MattM on May 20, 2024, 08:04:14 AM
Lawn mowers have used a magnetic clutch system for decades.  Your answer to torque at a certain point might use a similar method to kick in a bigger load or to brake.

Yes brother, I have no idea what you meant there. Please elaborate and I will be sure to do the same.


#4
Please let me get this out there!!

Should anyone know how to create a 1:30 drive. then please do not be shy..

I can maybe get to 22, even more perhaps 24 x!! and that is including knowing that the drive will become the weak point and break down rather fast!!!

1:30 stable? any ideas gang?
43
Wind / Re: axial generator with lamination core
« Last post by Adriaan Kragten on May 21, 2024, 02:49:29 AM »
What I have explained in my previous post for ratios 3/4 and 9/10 in between the number of coils and the number of armature poles is also valid for higher numbers. But the number of coils must be divisible by three and the number of poles must be even. So for a PM-generator with no iron in the coils one can use 12 coils and 16 magnets or 15 coils and 20 magnets or 18 coils and 24 magnets and so on. For a PM-generator with iron cores in the coils one can use 18 coils and 20 magnets or 27 coils and 30 magnets and so on.

For a PM-generator with iron cores in the coils there are better options than 9/10 like for instance 15/16 or 21/22 or 27/28. Lets take 15/16. Now the coil sequence is U1, U2, U3, U4, U5, V1, V2, V3, V4, V5, W1, W2, W3, W4, W5. So there are three bundles of each five coils. The coils in one bundel must be wound alternately left and right hand. The angle in between the coils is 360 / 15 = 24°. The angle in between the poles is 360 / 16 = 22.5°. So the difference is 1.5°. This means that there are 360 / 1.5 = 240 preference positions per revolution. This is much higher than for the ratio 9/10 and the peak on the cogging torque will threfore be much lower. A simular calculation will show that the ratio 21/22 is better than 15/16 and that the ratio 27/28 is better than 21/22.
44
User Diaries / Re: pigeons
« Last post by Mary B on May 20, 2024, 12:17:18 PM »
Quote from: TechAdmin on May 20, 2024, 10:34:17 AM
Big issue in my city everywhere... Mary got it right, spikes are the only viable solution.
... Or a rifle ;D

Rural too, pigeons love just harvested fields... I had close to 2,000 out back last fall...
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User Diaries / Re: pigeons
« Last post by TechAdmin on May 20, 2024, 10:34:17 AM »
Big issue in my city everywhere... Mary got it right, spikes are the only viable solution.
... Or a rifle ;D
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Logged in diaries / Re: VAWT backyard experiements
« Last post by electrondady1 on May 20, 2024, 09:45:28 AM »
That's a great spot for you mill.
How much space will you put between the ground and the bottom of the rotating body ?

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Logged in diaries / Re: VAWT backyard experiements
« Last post by MattM on May 20, 2024, 08:04:14 AM »
Lawn mowers have used a magnetic clutch system for decades.  Your answer to torque at a certain point might use a similar method to kick in a bigger load or to brake.
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Wind / Re: H-Darreius wind turbines ( VAWT ) !
« Last post by topspeed on May 20, 2024, 04:47:24 AM »
My new electrical part of the test rig.

15934-0

15935-1

I have not been able to make the new blades yet. I have been able to find and correct several weak points in the old set up.

Attachments: tormus.jpg * tormus.jpg tower5.jpg * tower5.jpg

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User Diaries / Re: pigeons
« Last post by Mary B on May 19, 2024, 09:22:07 PM »
Make strips of spikes that stick up, use some 3m VHB tape and tape them tot eh top edge of the panels.

Like used on my Davis Weather Station rain collector bucket



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User Diaries / pigeons
« Last post by tanner0441 on May 19, 2024, 03:42:03 PM »
Hi,

I only have three 400W panels, so I need every watt I can produce, they are on the roof of my workshop and only about twelve foot off the ground. I am having to wash them on an almost daily basis because the local pigeon and blackbird population like setling on them and it seems neither spiecis suffer in any way with constipation, in fact they all seem remarkably healthy.

Has anyone any idea how to deter birds from landing on solar panels or at least facing the other way round with their tails hanging over the space behind the panels..

Brian

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