Wow, thank you very much again for all the professional help. It's great that a group like this exists where a person like me can come on board and learn all this stuff from the actual people in the field who has experience! So I'm understanding what a rectifier does now.. and what an alternator is... and things are making more sense... if I'm producing AC at the hydrogenerator, that means I need to pass it through the rectifier & a capacitor (to smooth it out) before I charge the batteries right? So just wanted to verify the fact that I do NOT need to have a speed governor... because if I'm just going to pass it through a rectifier & capacitor to charge the batteries, I don't see why I would need to worry about trying to keep it at 60Hz... I could just set it at any Hz, as long as it falls within the specs of what the rectifier can handle, right? And in that sense, I don't even have to worry too much about the voltage (as long as it's high enough to push it for 800ft without much loss..), right? That system seems simple enough... So in summary, what it looks like I'm looking at is: 1) DC hydrogenerator --> #2 wire --> batteries 2) AC hydrogenerator --> thinner wire --> rectifier/capacitor --> batteries Is this a correct understanding? Now, one more thing which I'm not sure if it'll make any difference in this system... does it matter if the batteries are being trickle-charged by the hydro, while it's been also charged by the LP generator or while it's actually being USED by the houses (via the inverter drawing energy from the batteries)? Can the batteries be charged by 2 sources? Also, can the batteries be trickle-charging WHILE it's being drained by the inverter supplying energy to the house? This is not really a hydro-related issue, but thought that some of you might know this, also. Thank you again, --Daniel
Nando <[EMAIL PROTECTED]> wrote: LANCIE: and Daniel: It is quite immaterial for Daniel to generate precise 60 HZ, he DOES NOT need 60 Hz, at all, 70, 80 or so HZ is quite good for this small Hydro turbine generator -- he is using it for charging. Present transformers have wide frequency range like 40+ to 500 Hz due to the better silicon core material. He needs a simple set up with limited maintenance and a AC generator will fill his requirements. Also a High Voltage PMG Brushless 3 phase generator may fill his needs with transformers to convert to the battery bank voltage using a simple charge controller like the MX40 or a C40. 1000 Watts and 220 volts AC the single phase current is around 4.5 amps so using commodity wiring for 1000 feet the system may have a power loss around 14.5 to 23 watts ( 12 gauge is 1.588 ohms/1000 feet [ 3.176 ohms/2000 feet], 14 gauge is 2.525 ohms/100 feet [5.050 ohms /2000 feet] ). Transformers with 96-97 % efficiency or about 40 watts losses plus the rectifiers about 6 watts for a grand total of 23 + 40+ 6 = 69 watts or about 7 % transmission losses then the charge controller with its 94 % efficiency or 60 watts at maximum power for a grand total of 129 watts Out of 1000 WATTS 85 or so %. With 3 phase the losses will be reduced to abut 4 % . Using 35 amp diodes, 400 volts the MTBF life will around 1 million years, also the charge controller is operating at a low power level increasing its MTBF several fold. The Induction motor 3.5 HP operating at its less that 50 % rating will have many indeed many years life time, the bearings will be their limitation SO one with good oiling capabilities is a must. I indicated 1000 watts maximum, though the site may not give or generate that maximum Regards Nando ----- Original Message ----- From: <[EMAIL PROTECTED]> To: <[email protected]> Sent: Thursday, February 17, 2005 10:10 AM Subject: Re: [microhydro] AC vs. DC microhydro > > > Daniel, > > I am not a microhydro expert, but I have been an electrical engineer for 30 > years. I can see where your are having some trouble with the different > suggestions. > > You are looking at two basic practical methods: (1) Generate the power at > approximately 60 volts DC, then send it up two #2 wires to your batttery bank, > where it arrrives (after voltage drop losses in the wire) at the correct > charging voltage. (2) Generate the power at 120 or 240 volts AC, using a generator > that has some type of expensive troublesome speed controller (governor) to > keep the frequency at approximately 60 HZ, then transmit it up to your power > station, where you then step it down to a lower voltage using a transformer, then > change it back to DC using some type of "rectifier". A rectifier is an > electronic device that converts alternating current to direct current. > > Now, both Methods 1 and 2 have power losses involved. For Method 1, you have > the resistance of the wire, which is determined by the size of the wire. The > larger diameter of the wire, the smaller the losses. This is the method that > I would use, because over a long period of time, your costs will be less. > You can shop around and find some used wire of a large size that, at 48 volts > DC, will allow a very small loss, even at 800 feet. Once you get the wire paid > for, you have eliminated three possible maintenance headaches: speed governor, > transformer, and a rectifier. For a DC generator, you do not need a speed > controller, because a faster or slower speed just causes a change in the > magnitude of the voltage. There is no alternating frequency to worry about, so your > generator speed can be controlled by manually adjusting the the volume of > water going to the turbine. > > For Method 2, any time that you convert power from one form to another, there > are losses because there is not a conversion method that is 100% efficient. > This rule is based on the basic laws of physics. So at the transformer you > will probably have, for this small size, about a 5% loss. Then as you go from > AC to DC, you will have another 3 to 5% loss in the rectifier. Additionaly, > you will have 3 new devices to maintain and service. The transformer will last > many years without attention, but eventually the winding insulation will peel > off and will short out. The other two electronic devices may fail at any time > due to the heat caused by operation. > > Now, if you look at Method 1, using large wire for a DC voltage transmission, > it does not look so bad to me. Wire is one of the least likely devices to > fail. If you install the wire underground in a 1.5 inch diameter PVC plastic > conduit, it will last for 50 years without problems. > > > > > > > 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. 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