Need info, simple priority based load switching
By mukesh13, Section Wind Posted on Sun Jul 20th, 2008 at 08:05:13 PM MST
I have a small wind turbine going, all by only reading through this forum, without troubling anyone, yet. But I want to go for bigger one and need help now.

Background info ( skip to avoid being bored ) : ------------------------------------------------------ I have spent 2 years reading through the boards here. Made a failed attempt at a smaller solar panel (40w), then went and successfully made a relatively large one, approx 100w and used it for over an year now. It's in bad shape since I didn't frame it well. Somehow, was never happy with it. Now after reading and reading here in last 2 years, I have an alternator with 12" dual rotor ( 8 magnets on each, scourged from bad hard disks ) and a stator with 6 coils, 250 turns of #17 magnet wire. I put 3 pvc blaces of approx 5' on it. All mounted on a wheel hub of a popular vehicle in India. Not well designed enough though I fear. Patchy welding and ugly looking rotor casting. It somehow puts it approx 160W at around 14 mph and 500W+ at 20mph. All figures approx, diversion of 10% possible due to my not so expert calculations. All done without bothering anyone here, yet, over my stupid trials, courtsey intelligent inputs all across this forum from Flux, DanB, ghurd and so many others. It is kind of satisfactory after reading through experiences of so many others, but not enough for my needs. I am working on a larger, hopefully a 3 to 4 Kw machine ( @ 17-20mph ). It this attempt goes well, I will consider doing this on a full time basis and help others too. If it fails, it will be a huge setback, to my hopes. :( ------------------------------------------------------ Coming to my help request: I need some circuit or device which I can use in such a manner that the default or first connection leads to the battery bank. Till such time the RPM is at 150. Then once the RPM increases beyond 150, it should switch load 1 and then after another increase of 100 odd in RPM it should switch load 2 and so on. 2 is good enough, 4 will be divine. If there is a thread where it has already been discussed, please guide me there. All comments, questions welcome. Oh, by the way, I am a software developer by profession and I admit, all funds to experiment with wind energy were earned from the softwares I developed. :) Thanks in advance.

Need info, simple priority based load switching | 19 comments (19 topical, 0 editorial)

Re: Looking for simple priority load switching (3.00 / 0) (#1) by ghurd on Sun Jul 20th, 2008 at 02:40:47 PM MST (User Info)

I don't understand, but that is not uncommon. If the current should not flow until 150RPM, then that should be the cut-in RPM/Speed. It sounds like stall is going to be a major problem. If stall is not a problem, and 2 or 4 loads is good enough, then this should do it, (or at least provide a solid foundation) http://www.fieldlines.com/story/2004/8/22/212629/116 Another strange feeling, it could be adapted and integrated with this (maybe adapted), http://www.fieldlines.com/story/2005/5/14/123616/495 It feels like you may be missing some aspects of wind power. G-

Re: Looking for simple priority load switching (3.00 / 0) (#2) by mukesh13 (mukesh ##remove this part ## at b2a.in) on Sun Jul 20th, 2008 at 02:51:13 PM MST (User Info)

Hey, That was quick. No wonder you are a hero here :) I intend on low cut in machine and even if it stalls beyond a certain point like 400 rpm or so, that won't be an issue. It's a fairly windy area and though there are extreme windy days, most of the times it's between good and strong breeze, other than the times when there is no wind. "It feels like you may be missing some aspects of wind power." Not sure if that means I am losing out on some potential power that could have been tapped. If so, I think I have more or less made it a tradeoff. I couldn't get good welding help around and couldn't find a yaw bearing either. Not big concern for a smaller genie I would assume but for the larger one, I would prefer that it stalls on high speed rather than run away into neighbour's property. :) If you meant something else, I have a lot of learning still to do. I have been following your posts for a long time, and the dump controller I use is based on the one you did for 24V. Thanks. -> No is not the answer. Just a challenge. <- [ Parent ]

Re: Looking for simple priority load switching (3.00 / 0) (#5) by ghurd on Sun Jul 20th, 2008 at 03:18:46 PM MST (User Info)

"I prefer to learn from other's mistakes, somehow end up learning from my own". Me Too! "Not sure if that means"... It is related to the load at a certain RPM.  And loaded TSR and stall. I made more stuff that didn't work than you did, and I share related info. No title needed. I wish I knew more and learned faster. Nice to hear you found the circuit useful! G- [ Parent ]

Re: Looking for simple priority load switching (3.00 / 0) (#9) by Norm (peppysue@suite224.net) on Sun Jul 20th, 2008 at 07:15:53 PM MST (User Info)

Not big concern for a smaller genie I would assume but for the larger one, I would prefer that it stalls on high speed rather than run away into neighbour's property. :) That's what the furling mechanism is for to prevent it from 'running away'? and it can be made of wood if you are short on quality welding. ( :>) Norm [ Parent ]

Re:simple priority based load switching (3.00 / 0) (#3) by wooferhound (tim((NoSpamAt))wooferhound.com) on Sun Jul 20th, 2008 at 02:58:45 PM MST (User Info) http://wooferhound.com

Why do you want to switch  different loads on as the RPM increases ? Most of us use dump load controllers that switch loads on related to the batteries Charge level, this keeps the batteries from over Charging. I made a 2 stage dump controller that works really good. It switches a small load on when the battery voltage reaches 14.5 volts, then a much larger load when the bat volts reach 14.7 volts. http://www.fieldlines.com/story/2008/7/13/211414/932 W o o f -={(

Re:simple priority based load switching (3.00 / 0) (#4) by mukesh13 (mukesh ##remove this part ## at b2a.in) on Sun Jul 20th, 2008 at 03:16:13 PM MST (User Info)

I want to switch load based on priority. First priority is to keep the inhouse batteries charged. Next is to charge the batteries in the cattle shed, which is located at a distance. Finally, to do the dump load to operate some water fountain ( I have made small pond to keep some geese and fish ) or lights whatever as available. First 2 is a requirement, last one is optional. I chose to mention RPM because I 'assumed' it will be simpler to track. Voltage can be the criteria as well if that makes more sense. What you have done is actually nice, I had seen it earlier, but it is for 12 volts for one and If I dump 14 odd volts over 100 feet, to charge cattle shed batteries, the loss in transmission will be high. I would preferably transmit AC and convert near the batteries. This is what I learnt from all the reading here. Hope I am still in my senses, it is 2:45 am here in our side of the world. Thanks for your response and for all the help I have had from your responses to many such beginners in the past. -> No is not the answer. Just a challenge. <- [ Parent ]

Re:simple priority based load switching (3.00 / 0) (#6) by ghurd on Sun Jul 20th, 2008 at 03:42:00 PM MST (User Info)

"it is 2:45 am here".  Where is here? APO/FPO? The 3-phase AC loss of transmission has conditions.  AC and DC are about the same. Maybe something here is related... http://www.fieldlines.com/story/2008/7/13/35151/7106 G- [ Parent ]

Re:simple priority based load switching (3.00 / 0) (#7) by jonas302 on Sun Jul 20th, 2008 at 04:15:46 PM MST (User Info)

Could he use a dump controller to activate a relay or solid state switch to send the ac to the shed until the house battery came down again then another contoller on the shed battery to take care of the pond as a dump load I would think that would ensure your main battery was always taken care of first no matter what rpm [ Parent ]

Re:simple priority based load switching (3.00 / 0) (#8) by wooferhound (tim((NoSpamAt))wooferhound.com) on Sun Jul 20th, 2008 at 04:57:34 PM MST (User Info) http://wooferhound.com

That would also be my suggestion !! W o o f -={( [ Parent ]

Re: Need info, simple priority based load switchin (3.00 / 0) (#10) by frackers (g8ecj at *nospam* gilks dot org) on Sun Jul 20th, 2008 at 07:39:48 PM MST (User Info) http://www.gilks.org

If the shed is a much larger distance from the genny than the house then the extra cable required to get there may provide enough voltage drop that the house batteries get charged first anyway. If not, a series high current diode in the shed cable to 'loose' 0.7 volts will probably be enough to ensure that the house batteries are fully charged before the shed batteries take a significant amount of power. For running the pond fountain, a simple voltage sensor (eg a zener diode driving a transistor/relay combo) to turn on the pump when the shed batteries reach full charge or maybe monitor at the genny so that if the voltage rises significantly due to a high charge current then the extra load is turned on (using the pump as a dump load in effect!!) Robin - Down Under (or are you Up Over)

Re:Need info, simple priority based load switch (3.00 / 0) (#12) by mukesh13 (mukesh ##remove this part ## at b2a.in) on Mon Jul 21st, 2008 at 04:30:01 AM MST (User Info)

Hi frackers, I noticed you are in new zealand. First time I went there, I thought I landed in paradise... The feeling remains same still, if and when I get chance to be there. Any circuit references to to achieve : " For running the pond fountain, a simple voltage sensor (eg a zener diode driving a transistor/relay combo) to turn on the pump when the shed batteries reach full charge or maybe monitor at the genny so that if the voltage rises significantly due to a high charge current then the extra load is turned on (using the pump as a dump load in effect!!)" Thanks and enjoy the paradise. -> No is not the answer. Just a challenge. <- [ Parent ]

Re:Need info, simple priority based load switch (3.00 / 0) (#13) by DamonHD (d@hd.org) on Mon Jul 21st, 2008 at 05:04:29 AM MST (User Info) http://www.earth.org.uk/

Hi, I use my main Internet server/laptop as a dump load, see: http://www.earth.org.uk/low-voltage-drop-out-circuit-design.html This involves an LVD with higher-than-usual voltage thresholds to only divert power to the laptop when the battery is pretty full and being charged and I also have some monitoring and software tweaks on the laptop to ramp up power consumption further if the voltage continues to rise.  This makes a variable dump-load of between about 20W to 60W for my small system. Rgds Damon [ Parent ]

Re:Need info, simple priority based load switch (3.00 / 0) (#14) by mukesh13 (mukesh ##remove this part ## at b2a.in) on Mon Jul 21st, 2008 at 07:18:25 AM MST (User Info)

Hi Damon, It looks good. Any idea on adapting it to 24V ? Thanks again for sharing. -> No is not the answer. Just a challenge. <- [ Parent ]

Re:Need info, simple priority based load switch (3.00 / 0) (#15) by DamonHD (d@hd.org) on Mon Jul 21st, 2008 at 10:32:02 AM MST (User Info) http://www.earth.org.uk/

I think that the control IC is good up to 30V, but check the data sheet.  I think that the P-MOSFET I happened to use would also be OK, but (a) check and (b) there's nothing magic about it. Then all you have to do is adjust the resistor values for the voltages you want.  Easy. Rgds Damon [ Parent ]

Re: Need info, simple priority based load switchin (3.00 / 0) (#18) by Ungrounded Lightning Rod on Tue Jul 22nd, 2008 at 08:22:13 PM MST (User Info)

If the shed is a much larger distance from the genny than the house then the extra cable required to get there may provide enough voltage drop that the house batteries get charged first anyway. If not, a series high current diode in the shed cable to 'loose' 0.7 volts will probably be enough to ensure that the house batteries are fully charged before the shed batteries take a significant amount of power. Adding a diode drop means the shed batteries will never achieve full charge.  Meanwhile the house batteries will require a dump load that goes on even if the shed batteries aren't yet fully charged. [ Parent ]

Re: Need info, simple priority based load switch (3.00 / 0) (#19) by mukesh13 (mukesh ##remove this part ## at b2a.in) on Wed Jul 23rd, 2008 at 08:28:06 AM MST (User Info)

Hi, I tried this. It won't happen the way you noted. If I add a diode and then keep the shed batteries connected too, AC, not the DC connection, then the voltage at the batteries in house, after conversion, is more than the voltage in the cattle shed, so the house batteries end up getting charged first. Though not exactly a clean solution, since both systems are connected effectively in parallel and there is a trickle charge in anycase to the shed batteries almost all the time. the way the site is organized : WindMill ^ | 20 metres. | [House ] ^ | 10 metres      <--------50 metres------->[ pond] | | | 40 metres   < ------40 metres-------->[cattle shed] AC to DC conversion is done at the batteries location. Not a very good site design above but should be enough to give some idea. Overall capacity of generation is much above what I need so keeping some lights for cattle all the time doesn't seem to hurt me... I need to watch the results over next few days. Thanks for the inputs. -> No is not the answer. Just a challenge. <- [ Parent ]

Re:Need info-simple priority based load switching (3.00 / 0) (#11) by mukesh13 (mukesh ##remove this part ## at b2a.in) on Mon Jul 21st, 2008 at 12:41:34 AM MST (User Info)

Thanks for all the guidance. Ghurd, Thanks for encouraging words. I can only guess how much you might have gone through to be able to guide us, the lesser mortals. :) And 'Here' is India, not APO/FPO. :) Norm, Wood is pretty expensive here for the quality needed for this work. And labor for that is not cheap either. Letting go of some potential seems to work better than running after the ones who will work on it. Besides, the mills with better machines won't have time to work on such small tasks and the normal carpenters are too low-skilled to depend for these tasks. Jonas and Woof, Using dump controller to activate a SSR : Will it require modification to the existing dump controller? Any ideas, suggestions on the same? Right now, the dump controller is connected to the batery and dump load is DC and not AC. frackers, I will try your suggestion, possibly coming weekend and will post results. While the dump controller I tried works well, other attempts on electronics haven't been too satisfactory so I will prefer if your suggestions do the trick. Seems lesser hassles in those. And, hey, thanks to you all again. I always knew I will get the help, and I have been always right, except when I am wrong. :-) -> No is not the answer. Just a challenge. <-

Re:Need info-simple priority based load switching (3.00 / 0) (#16) by Flux on Tue Jul 22nd, 2008 at 02:01:26 AM MST (User Info)

I have done some of these load priority schemes, one gave priority to an electric fencer battery then charged other batteries when excess power was available. I used series mosfets with voltage sensors, but I really wouldn't like to tackle something like this without some basic electronic skills. Simple solutions are often better for those without electronic skills. Not sure if you transmit ac or dc but it may be a good idea to run a separate line from the mill to the cattle shed and normally let the two batteries charge from the common source ( better if the lines are ac and they both have rectifiers at the battery. As long as the cable to the cattle shed was higher resistance the house battery would get more charge. In periods of low wind you could switch off the charge to the cattle shed to get everything to the house. In times of high wind when everything is fully charged you could again switch off the cattle shed and use the dump controller on the house battery to dump to your fountain. If you wanted less manual intervention then a second dump controller on the cattle shed battery would make it a bit more foolproof. Flux [ Parent ]

Re:Need info-simple priority based load switch (3.00 / 0) (#17) by mukesh13 (mukesh ##remove this part ## at b2a.in) on Tue Jul 22nd, 2008 at 08:57:16 AM MST (User Info)

Thanks for your inputs Flux. That completes the responses from nearly all the heroes and experts on this board. :) Yes, I agree with the need to keep it simple, it will work better I hope. The idea with going ahead for a wind mill is not just meeting requirements but enriching myself too in terms of knowledge and understanding and somehow broadening the horizons. I know of several people here who are interested in the alternative technologies if only someone can help them with some inputs, some direction to get the started or show some light when they are lost. In the process of getting my own wind mill and solar panels, I tried to think for them too. So much for my political speech. Any inputs/guidelines about how you designed your electric fence and then further dump will b appreciated. For my immediate issue, I think I have enough inputs to work out a solution for the time being. Thanks to everyone who answered. -> No is not the answer. Just a challenge. <- [ Parent ]

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