I have been reading all the answers here with interest as I also have a large distance, some 200m from the waterfall to my house (in France). I have always assumed that I would generate say 48VDC at the water fall location and have the battery bank down there together with the inverter and send the inverted 240V AC back up to the house as needed. Also, this way I can connect several sources in parallel, another waterwheel or some solar panels down at the battery end. This way I can keep everything neatly away from the house and "pretend" I get normal grid AC supplied to the house:-), although I might get some occasional excersise running up and down the hill... Last time I checked, I think the losses in the cable, 16mm armoured suitable for burial for say 3KW peak load at 240W wasnt that bad, 3.2% or 7.3V and the cable wasnt extremely expensive or cheap either....165GBP per 100m. (Good cable data and clculator at www.tlc-direct.co.uk) Best regards /Bjorn
Nando <[EMAIL PROTECTED]> wrote: Daniel: You have 3 types of generators: A DC Generator ( most of them have brushes that need periodic replacement and some times the commutator needs truing) A Permanent Magnet Brushless 3 phase alternator that produces AC a much higher frequency that the system you have installed. An Induction Motor that is converted into a generator , and this unit can be single phase or three phases. In the last 2 cases the design will require DC conversion for the batteries, via DIODE Rectifiers ( convert the AC into DC. You may get from 500 to 1000 watts from your water source, with 500 watts you attain 84 KWH weekly. The question is what are your capabilities for mechanical and electrical work or does somebody else will be doing the work ?. For a battery bank of 48 volts, 1000 feet of DC carrying current at around 10 to 20 amps makes the cabling expensive. The system can afford to have some minima losses using the proper design. An induction motor, 220 Volts,3 phase STAR and 3 to 3.5 HP attached directly to a Turgo Turbine and sending all three phases to the battery bank with three transformers - down converting to battery bank levels and 3 phase rectification for minimal electronic charging control -- with current charging limiting or ideally with MPPT for easy control of the generator -- to avoid stalling the INDUCTION GENERATOR and at the same time to attain maximum power transfer. MX40 Charging controller may do. Or a C40 from Xantrex. You need to define the true seasonal water volume available to determine the best procedure for the Turbine and its water management and to attain greater power. Regards Nando ----- Original Message ----- From: "Daniel Kim" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Thursday, February 17, 2005 2:22 AM Subject: Re: [microhydro] AC vs. DC microhydro Okay... just went through all of the email thread -- I really really appreciate all of you (some of you quite passionately) posting to help me out.. Now, I am getting a little bit more sense of what is necessary here.. and what kind of parameters / limitations I need to consider... Well, as mentioned before, here's a list of parameters that I have to work with: 1) completely off-grid system 2) a big main battery bank (48V @ 1700AH) hooked up to 15KW LP generator for peak usage backup 3) a rack of Trace (or Xentrax) inverter/charger is hooked up between the LP generator and the battery bank. It can handle up to 120amps. 4) main battery bank will eventually be hooked up to 3 cabins (one of them being a 2500 square feet residence!). 5) weekend usage only, but we can assume that it's almost every weekend. Assume that during the weekend, we'll be using something like 40-50KWH. 6) creek is 800-1000ft away from the battery bank, 120ft head w/ 60-70GPM flow 7) we're willing to spend up to $6,000 on the hydro system, if it can fully charge the batteries (which would be able to store about 40KWH of usable power - at 50% discharge limit) during the weekdays. I think having these parameters will actually help narrow down the choices a bit... Basically, we're hoping that with the hydro charging the batteries throughout the week when no one is there, we won't need to use the LP generator (especially with the skyrocketing price of propane these days) as much. So, it is not an option for me to run directly off of the AC hydrogenerator... it has to charge up the battery bank (b/c of the high usage during the weekend). And because of the high storage of the battery bank, we would like to get as much power out of the stream as possible (i.e., minimize power loss). Now, many of you guys are talking about rectifiers and transformers and alternators and induction motors, etc... I'm sorry, but I have a hard time understanding that.. (please have patience, I'm a newbie!) So far, I've basically figured out what an inverter/charger does... I understand AC & DC, and I understand the basic way that voltage and amperage works. But I don't know what a rectifier does... does it convert AC to DC?? But wouldn't my inverter/charger do that for me? What's an alternator? Anyway, for that reason, I am having a bit of a hard time understanding what is actually being suggested by many of your postings. Hopefully, with the parameters that I listed above set, it will narrow down the range of possibilities... It seems like some of you were being very creative with what I could do! That's great, and I really appreciate that.. but the reality is that my range of possibilities isn't that wide... so with my parameters, perhaps all those ideas with rectifiers and alternators would not be applicable?? Not sure. Now, moving onto the things that I DO understand... I see that some of the postings have suggested that I just get a DC hydrogenerator and just get thick #2 wires to transmit the power up to the battery bank 800-1000ft away. That's an idea that I at least understand. I also understand that DC current is safer than AC. But I also understand that DC current doesn't travel as well as AC -- even with a #2 wire, wouldn't the power loss be pretty significant? Even at something like 48V, wouldn't the loss be significant? And the added cost of a #2 wire is also something that I'm concerned about, as it will add about $700 more to the wiring, right? But I'm open to suggestions. If DC generators are cheaper than AC generators and the power loss over #2 wires is not that much, maybe I can buy into that... Any thoughts on this? Another posting suggested that I get a DC hydrogenerator powering a small battery bank, and then use an inverter to convert it to AC and make it travel... that's something that I also understand... And I DO have a small battery bank (just a 1KWH storage system)... so that idea sounds intriguing. Basically, I would put the small battery bank and the extra cheap inverter down at the stream next to the DC hydrogenerator, and let the hydrogenerator charge the batteries, and let the inverter convert the battery voltage to AC and push it for 1000 ft, right? Now, I'm just wondering what advantage this particular system would have over me just getting an AC hydrogenerator to begin with (since it looks like this system is basically "simulating" an AC hydrogenerator). Wouldn't it be simpler to just buy an AC hydrogenerator? Or maybe there's some nice advantage to having this DC->batteries->inverter->AC system that I'm not seeing? Anyway, this is sort of where I'm at here.. Hopefully that gives you a better idea of my knowledge level and my situation. When there's all these parameters & limitations, sometimes the job becomes easier - and hopefully this is one of those situations where the limitations that I have @ my site actually makes the job easier. Thank you again for all your postings, it has been tremendously helpful.. although at times I didn't really understand what all those terms meant... Please have patience with me, I'm learning as fast as I can. Thank you again, I really appreciate it. --Daniel --------------------------------- Do you Yahoo!? Meet the all-new My Yahoo! - Try it today! [Non-text portions of this message have been removed] Does your company feature in the microhydro business directory at http://microhydropower.net/directory ? If not, please register free of charge and be exposed to the microhydro community world wide! NOTE: The advertisements in this email are added by Yahoogroups who provides us with free email group services. The microhydro-group does not endorse products or support the advertisements in any way. More information on micro hydropower at http://microhydropower.net To unsubscribe: send empty message to [EMAIL PROTECTED] Yahoo! Groups Links Does your company feature in the microhydro business directory at http://microhydropower.net/directory ? If not, please register free of charge and be exposed to the microhydro community world wide! 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