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Forum Index : Electronics : Automatic Star Delt Switching
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JimBo911 Senior Member  Joined: 26/03/2009 Location: United StatesPosts: 262 |
Do any of you guys know where I can get a switch that will put my mill in either Star or Delta automatically. Jim |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Hi Jimbo How handy are you with a soldering iron? There's a few automatic circuits out there, but they can be a bit complicated. This one uses 3 relays and monitors the windmill RPM. http://www.dsgnspec.com/StarDelta.html You could use a switch to manually operate the relays instead of the electronics. You just need to find some way to operate the switch. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
The star/delta switching is a mechanical arrangement that is persisting to be discussed. It is obvious that the windmill you have works in delta. Leave it connected this way. For windmills around 1kW peak output, all you need is an additional 3phase capacitor voltage doubler connected from the 3 windmill AC leads to the battery. The capacitance will be around 470uF AC rated at least 2X system voltage. There will be no speed sensing or switching relays. For smaller windmills, the capacitance is reduced proportionally. Keep the mechanical relays for the electrical brake. Gordon. become more energy aware |
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| JimBo911 Senior Member Joined: 26/03/2009 Location: United StatesPosts: 262 |
Hi Glen Got your message about my posting (Windmills, subject) Gordons AX FX. I have tried to contact dsgnspec.com a couple of times with no result's. I have used a soldering iron several times but honestly I am not the guy to build one. I am sure I could build a manual switch but was hoping for automatic switching. Thanks Jim |
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| JimBo911 Senior Member Joined: 26/03/2009 Location: United StatesPosts: 262 |
Gordon Thanks for your help and your knowledge. It's folks like you others on this forum that help people save tons of money and lots of hours of work etc. I am getting close to finishing my mill. Now it's time to start wind trials kinda like sea trials for a new ship. I have to shift to the electrical part and of course furling, tail set up. Keep up the good work my friend cause were watchingand learning. Thanks Jim |
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| carl1 Regular Member  Joined: 16/04/2007 Location: AustraliaPosts: 79 |
If you really want to switch from star to delta you could use a low pressure air flow switch ( see my previous posts )to trigger the switching only depending on the wind speed. I use this to shorten/ stop the mill when the wind gets too strong. Harald |
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AMACK Senior Member Joined: 31/05/2009 Location: AustraliaPosts: 184 |
I too am after a auto switch from Delta to star. I think Smart drive( Cameron) has got a 48 volt system set up that way. From the comunications I have had he uses a stepper switch? I have also looked at the Link Gizmo put up but I think it is very old and I did not get any E mail back also. I did like the system they used but I dont know if it is still around... Dam..Looked good.. I looked at Harald (carl1) set up but alot of room for error I think. I would like to see a few disigns or photos before I could make a finial dission on the idear. It may work well from the way he talks.. AMACK *Note to self 1. Make it thick 2.Make it heavy. 3.Make it stronger than it should be. 4. Don't rush the first job as the second job will cost more and take mor |
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| GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Star delta switching requires delays and hysterysis. I had a picaxe as the controlling element, with 2 x spst relays to switch in extra rectifiers at the star point, this was not delta, but sort of independent rectification. Only a problem with slip rings, as U need 4. I would not go this way again, as staggered windings and cap arrangements are far better. A location with anything but constant windspeed, laminar airflow will quickly wear the relay. If you want I can show you a graph of the expected relay switching cycles needed in typical conditions. Gordon. become more energy aware |
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| AMACK Senior Member Joined: 31/05/2009 Location: AustraliaPosts: 184 |
Can you send me some info or the posting to read. I have a few motors and mags and want to put together another mill. Any feed back is a help as every person I talk to has a diffent Idear of what is the best way to go.  *Note to self 1. Make it thick 2.Make it heavy. 3.Make it stronger than it should be. 4. Don't rush the first job as the second job will cost more and take mor |
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| JimBo911 Senior Member Joined: 26/03/2009 Location: United StatesPosts: 262 |
Gordon At the present time my batteries and invertors are set up for 12 volts which I do not care for, later I would like to jump up to a 48 volt system but for now 12 volts will have to do. Preliminary wind testing with my stator set up in star produces 12 volts at very low rpm which stalls the blades very quickly. I like your idea about 3 phase capacitor voltage doubler and I do understand the principal of how it rectifies and raises voltage. There is of course many ways to wire a voltage doubler system my question to you is do you know where I can get an electrical schematic that would work best for my system so I can more forward with this arrangement. My stator is a 60dc-7s-2p Jim |
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| GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi Jim, there may be many ways to wire the caps, but only this way seems to be effective. My wiring arrangement appears to be novel and I have recently been confirmed of how well it works on my new mill. For a 12V setup, leqave the alternator in delta, and make a cap voltage doubler using 100V bipolar audio caps. 50uF would be a good size to start, considering the single stator. You would only require 10A rectifiers as well. A lot simpler than sensing and relays and the wiring loom needed at the alternator for a mechanical switching system. Gordon. Gordon become more energy aware |
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| GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
From the lack of informed responses to this question I will provide some good reasons why mechanical switching of a dynamic windmill system is likely to end with failure of mechanical components. You really have to ask ?? Is there a successful commercial implimentation of star delta switching? Here is a graph of a typical windmill output in a 15hour operation window. There was about half the time with low winds, and the other half was variable/reasonable winds. 
rotor RPM is the teal coloured graph, and output power is the yellow graph. There were many wind gusts during this recording window. There are approximately 2000 RPM transitions through a set point of 180rpm. Now, if I had a relay, star/delta switching system, it would be required to change the windmill wiring configuration 2000 times. I will let the readers think about this a bit, and it will be obvious why I have chosen a switchless arrangement to achieve the optimum loading on my windmills. Gordon. become more energy aware |
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| JimBo911 Senior Member Joined: 26/03/2009 Location: United StatesPosts: 262 |
Thanks Gordon I now have a good starting point to being my cap doubler. Progress on your new mill is very exciting keep up the R&D. Jim |
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| AMACK Senior Member Joined: 31/05/2009 Location: AustraliaPosts: 184 |
I to might go the cap and stagger way and not by switch way.. After reading Gordon's data I think the relays would work for about a week in my location. I am thinking of staggered wireing and voltage doublers for mills with big distances from the battery bank. The web site www.allaboutcircuits.com is a good read, it was listed in a forum topic and I thought I might have a look ( well worth it ) Andy *Note to self 1. Make it thick 2.Make it heavy. 3.Make it stronger than it should be. 4. Don't rush the first job as the second job will cost more and take mor |
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| AMACK Senior Member Joined: 31/05/2009 Location: AustraliaPosts: 184 |
Jimbo911, Take a look at www.allaboutcircuits.com you might find what you are looking for. 
*Note to self 1. Make it thick 2.Make it heavy. 3.Make it stronger than it should be. 4. Don't rush the first job as the second job will cost more and take mor |
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| GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi AMACK, the charge pump cct you posted above is not suitable for a windmill. The series arrangement of components is the giveaway. My 3phase parallel setup, linked to in my post above, has low impedance to deliver amps, not mA. Gordon. become more energy aware |
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| AMACK Senior Member Joined: 31/05/2009 Location: AustraliaPosts: 184 |
Gordon. Can you post me it direct as the image is to small. When I open it I can not read it at all. gemleighmeadows@bigpond.com.au Andy *Note to self 1. Make it thick 2.Make it heavy. 3.Make it stronger than it should be. 4. Don't rush the first job as the second job will cost more and take mor |
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| Dinges Senior Member Joined: 04/01/2008 Location: AlbaniaPosts: 510 |
[quote=Gordon]There were many wind gusts during this recording window. There are approximately 2000 RPM transitions through a set point of 180rpm. Now, if I had a relay, star/delta switching system, it would be required to change the windmill wiring configuration 2000 times.[/quote] It depends on the integration time you use for switching, and the amount of hysteresis you'd set it up with. If you have a simple algorithm that directly switches from star to delta at 180.0 RPM, and back again at the same threshold, then the relais will do a lot of switching. If however you integrate over a, say, one-minute period and switch once a minute, then that would seriously reduce the amount of switching. If you then also add a bit of hysteresis so the relais won't chatter (as RPM will likely drop again in delta, due to lower impedance and thus higher loading/more delivered watts -> lower RPM -> switching back to star), that should greatly help in reducing the wear on the relais. Solid-state relais would be another solution to overcome the problems of mechanical relais. Mechanical relais have been used in industry for control purposes for over a hundred years. Machines with hundreds of relais work reliably for many years. So, I see no reason why the same relais couldn't be used for wind too - provided one uses them sensibly, i.e. with an integration period and hysteresis. About the circuit AMACK showed - I agree with what Gordon said. The circuit AMACK mentions is a Cockroft-Walton multiplier. It's a simple and cheap way of generating very high voltages (I played around with them in the past and got up to 100 kV (estimated) using 3 multipliers from a colour TV) but only at small currents (less than a mA). Ideal to generate 25kV for a CRT in a TV set, or the high-voltage for a X-ray tube (ah... the foolishness of youth - good thing I didn't have internet back then, or I'd have probably succeeded in building and operating a X-ray machine; a few months ago I finally said goodbye to that part of my youth by throwing away the valves that would have been useful in such experiments. My offspring will thank me for that....  )
The circuit is not useful to increase the voltage of a windturbine though. You could check out boost converters too to increase the voltage. If you google around for this term, you should find plenty of circuits. I'm not a fan of them myself, but if you really feel like you have to increase output voltage this way (and not the 'correct' way by rewinding the alternator) then you could give it a try. Peter. |
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| GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
All I can say is that persisting with mechanical switching, when a better system is available is really up to the individual. The dynamics of wind, and the required alternator loading dictates that the windmill rpm should track the windspeed closely. Any system that relies on long time delays and sensing parameter hysterysis will not allow the windmill to operate anywhere near optimum efficiency. Somewhere on an exposed cliff with winds unobstructed may be a suitable location for a windmill fitted with a mechanical switching system. ACSSRelays have their own problems with voltage thresholds and the number of individual ganged switches needed. The winds that frequently result in locations where we live are affected by buildings,trees,hills etc. I have recorded gusts where I live, that have a duration of 10-30 seconds, interspersed with lulls, and sometimes more sustained gusts come through. Down the road on the beachfront, the winds are more consistent, but millionaires row might not appreciate the green perspective of windmills. Wind the alternator if possible for cutin at half expected maximum rotor rpm. Connect Cap AC voltage doubler/triplers etc to extend the useful harvest rpm down to a level of probably 5-10W available wind energy for the rotor. The resulting alternator will load the windmill with a cubic power relationship without any sensors or microprocessors. The small amount of trialling with cap sizes is far easier than remaking and testing of any wiring combination of a stator. Star/delta switching sounds like a simple solution, but at best is really gives 2 poor approximations of loading, and this depends still on the blade match, and load match etc. As I have proven with my AxFx design, a stator that would be classified as suitable for 96V system only, heavily stalled on 48V[max output approx 30W into 48V battery], performs near optimum on 48V loading with AC coupling and effectively a cap voltage quadrupler and cap voltage doubler. As long as Capacitors and rectifiers are available, they will work better than any star/delta switching arrangement. Gordon. become more energy aware |
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| JimBo911 Senior Member Joined: 26/03/2009 Location: United StatesPosts: 262 |
Andy Thanks for thinking about me and my mill. Good luck with your rebuild.  Jim |
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