Hi Eric, I also use a 3 phase capacitor excited induction motor. Just be carefull not to have too much load in the dump loads or the field will collapse and lose excitation. I have a 3 hp motor, 1800 rpm rated running at ~2300 rpm. When I put the 3 16 ohm loads in at first I had them in wye on all 3 phases, but that didn't work and the system would freewheel after loosing excitation. So I went to the 3 16 ohm loads in series across only two legs. This scheme should actually work more reliably with a PM type alternator or a powered field type alternator.
More details of my system are at the following link (not updateded for this new mod) http://h-hydro.com/Aspen_Hollow_Hydro.html Joe --- In [email protected], [EMAIL PROTECTED] wrote: > > Hello, > > Very good description of your system. > Very interristing for me in direct application ! > Thanks a lot > > I've got the same system of your > > I don't use all the power i can use because of the dumps load who are > limited in power. The dump loads are standard 240V 3000W water > heaters on a pressure tank.(3 phases 400V/240V standard electric boiler) > But y use them in 24V so only 300W is used. > If i use them on the 240V line, i will dump 9000W (only 1300W are OK > for me) > I've got the solid state relays in stock ! and the resistors too ! > (3 phases relays with 3-32V DC command( internal 40VDC protection) > Carlo gavazzi or crouzet) > > So i will try this arrangement soon. > My generator is an old induction motor used in generator with capacitors. > What is your ? > > Regards > Eric > > > ----Message d'origine---- > >A: [email protected] > >De: "Joseph Hartvigsen" <[EMAIL PROTECTED]> > >Date: Fri, 16 Dec 2005 20:25:11 -0000 > >Sujet: [microhydro] Re: Alternator recommendations > > > >I agree with Rob that for small systems it is much simpler and more > >reliable to regulate the power rather than the water flow. Most of > >these small systems will be used for battery charging, but the power > >may be delivered as AC at higher voltage. In such cases there is an > >easy way to regulate the system by putting the dump load across the AC > >line rather than the DC. > > > >Rather than deal in general terms I'll explain how my recently > >modified system is set up. > > > >Power comes from the turbine driven induction motor as 3 phase AC at > >about 167V. > > > >[A side note: It is at 167V because it then goes to 3 transformers > >setup as 240V (delta) primaries and 32V wye/star secondaries then to a > >3 phase bridge rectifier with the output connected to a 48V (56V > >typical) battery bank. Unlike single phase, where the RMS voltage of > >the rectified sinewave DC output is exactly the same as the RMS AC > >input, in 3 phase the DC output voltage is 1.35 times the leg to leg > >AC voltage. So, the battery clamps the rectifier output to 48-56V > >depending on state of charge, which means the AC phase to phase input > >is ~52/1.35 = 38.6Vac, which means each of the transformer secondaries > >forming the wye/star is 38.6/sqrt(3) = 22.3Vac, that means the > >primaries are 240*22.3/32 = 167V. If I had used nominal 24V output > >transformers in wye to the 3 phase bridge, the primaries would run > >closer to the rated voltage. 24*1.35*sqrt(3) = 56.1V ] > > > >I used a solar charge controller, Morningstar TS-45 and configured it > >in diversion load mode with its inputs connected to the battery +/- > >and outputs connected to two resistors in series. These resistors can be > >relatively low wattage, sized for only 30-50mA. For example with 60V > >peak battery equalization voltage, split across two resistors 50mA*30V > >= 1.5W and 30V/0.05A = 600ohm. So you could go with two standard > >value 680 ohm or even 1k-ohm resistors rated at 5W or 10W connected in > >series and connected across the TS-45 load +/- terminals. Clearly this > >won't dissipate much power, but it does provide a 24-28Vdc signal > >between the load (-) terminal and the point between the two resistors > >which I use to fire AC solid state relays (SSRs). If you have a 12 or > >24V battery bank you can fire the 3-32Vdc triggered type AC SSR > >directly from the TS-45 output terminals. If you have higher than a > >48V battery bank use more of the resistors in series and take the SSR > >trigger (+) signal from the opposite lead of the resistor connected to > >the (-) terminal. > > > >Now, whenever the battery bank voltage is at the control limit, the > >TS-45 in trying to dump power actually just sends a signal to trigger > >the SSRs. The SSRs are connected to AC line voltage from the hydro on > >one side, and a load resistor on the other side. You can find these > >relays rated to 25A (using a heat sink) at 240V for about $20 each at > >most electrical supply places. > > > >I had previously used some old oven and drier heating elements, but > >they took up too much space on the wall. So I put three 300W 16ohm > >edgewound and enamel coated resistors in series across the 167V from > >the hydro. That will dump in my case ~580W, but it is easy enough to > >size these resistors to dump what power you need at the generator line > >voltage. > > > >I purchased the resistors from digikey.com The 300W version are $16.48 > >each, part number FVE-300-xx (xx is resistance in ohms from 0.5, 1.2, > >2.0, 5.0, 8.0, 10, 12, 16, and 20). A larger 1000W resistor (black > >silicone finish rather than enamel coated) is available for $51.50 > >each, part number FSE1000-xxx (-.25, .50, 1.0, 3.5, 4.5, 10, 15). Both > >also have a mounting kit available. Of course if you have a useful AC > >load of appropriate power and voltage rating that can be connected and > >disconnected such as a water heater use it. > > > >So, in simple terms, the PV load controller senses battery voltage, > >triggers SSRs which connect an the AC diversion load across the lines > >from the hydro. > > > > Joe > > > > http://h-hydro.com > > > > > >--- In [email protected], [EMAIL PROTECTED] wrote: > >> > >> A quick general note regarding regulation. It is my experience that > >in smaller > >> systems regulation is best done at the electrical output end rather > >then water > >> intake end. A power diverter using IGBT or TRIAC power elements, or > >even > >> relays, is by far the cheapest and most reliable way to govern the > >output of < > >> 5 kilowatt output systems. In the < 100 volt range these units are > >available > >> off the shelf from many vendors, while the 120V and up systems are > >more costly > >> and somewhat harder to to source. At the end of the day they are > >still a better > >> investment if only for the reason that you might still want one even > >with a > >> water flow diverter installed, in case the valve sticks open. > >> > >> Rob > >> > >> > >> > >> Quoting tom kasmer <[EMAIL PROTECTED]>: > >> > >> > > >> > > >> > > >> > > >> > > >> > > >> > using a PM motor as a generator has the following > >> > > >> > tenet. It has > >> > > >> > no regulation mechanism other than shaft speed, so > >> > > >> > here's what I suggest. You could rig up a smart bypass > >> > > >> > of the flow to regulate the speed so as to regulate > >> > > >> > the output power. Im sure that a magnetically coupled > >> > > >> > rotor excitation will indeed be expensive. > >> > > >> > Having a lot of experience in the fields of > >> > > >> > electricity and magnetism, unless this fancy generator > >> > > >> > has a few successful years > >> > > >> > of use in the field, I would stay away from it. You > >> > > >> > will have little or no recourse if it fails since is > >> > > >> > not in a car. Tom > >> > > >> > > >> > > >> > --- williameverettstone <[EMAIL PROTECTED]> wrote: > >> > > >> > > >> > > >> > > Thanks for the reply. > >> > > >> > > > >> > > >> > > 50gpm is the minimum flow even in times of drought. > >> > > >> > > > >> > > >> > > Several formulas on the net showed we could expect > >> > > >> > > to produce about 20 > >> > > >> > > watts w/ 50gpm and 4-5' head. This equates to 1.6 > >> > > >> > > amps at 12 volts. I > >> > > >> > > figured 1-1.5 just to be realistic. > >> > > >> > > > >> > > >> > > Thanks for the advice on PM motors, I'll check them > >> > > >> > > out. Since posting > >> > > >> > > I found that Delco has come out with brushless > >> > > >> > > alternators available > >> > > >> > > in 12, 24 and 48 volts. I'm waiting for a quote on > >> > > >> > > one now, rewound to > >> > > >> > > produce at lower RPM. I expect it's going to be too > >> > > >> > > pricey. > >> > > >> > > > >> > > >> > > Thanks again. > >> > > >> > > > >> > > >> > > > >> > > >> > > > >> > > >> > > --- In [email protected], tom kasmer > >> > > >> > > <[EMAIL PROTECTED]> wrote: > >> > > >> > > > > >> > > >> > > > > >> > > >> > > > my experience witn GM alternators is that the > >> > > >> > > brushes > >> > > >> > > > will last > >> > > >> > > > about 150,000 miles + or -. That is a half year of > >> > > >> > > > steady driving. The alternator is subjected to > >> > > >> > > > underhood temperature extreemes and wild > >> > > >> > > > accelerations. In an outdoor enclosed housing, > >> > > >> > > > running at a fairly constant speed, you might get > >> > > >> > > a > >> > > >> > > > year of 24/7. > >> > > >> > > > Your 1-1.5 amps sounds low. How did you get that > >> > > >> > > > number? As far as PM generators, any PM motor will > >> > > >> > > > work nicely as a generator. > >> > > >> > > > 4 feet of head is only 2 psi of pressure. How much > >> > > >> > > > total flow > >> > > >> > > > does the creek have worst case drought time? Is > >> > > >> > > that > >> > > >> > > > the 50 gpm number? If you are limited to this > >> > > >> > > level of > >> > > >> > > > power, that is about > >> > > >> > > > 20 watts best case with an automotive generator. > >> > > >> > > You > >> > > >> > > > might better spend your budget on a photovoltaic > >> > > >> > > array > >> > > >> > > > and settle for > >> > > >> > > > daylight only solar power with less hassle. Im not > >> > > >> > > an > >> > > >> > > > expert in microhydro power so others may do > >> > > >> > > better. > >> > > >> > > > Tom Kasmer > >> > > >> > > > > >> > > >> > > > --- williameverettstone <[EMAIL PROTECTED]> wrote: > >> > > >> > > > > >> > > >> > > > > Hi All, > >> > > >> > > > > I have a situation with minimum 50gpm flow year > >> > > >> > > > > round (I have been > >> > > >> > > > > measuring for 5 years, through drought and > >> > > >> > > different > >> > > >> > > > > seasons). > >> > > >> > > > > > >> > > >> > > > > My wife and I are planning to rebuild the > >> > > >> > > remnants > >> > > >> > > > > of a small dam on > >> > > >> > > > > the creek which would provide about 4' head. We > >> > > >> > > > > estimate we could > >> > > >> > > > > generate 1 to 1.5 amps here. > >> > > >> > > > > > >> > > >> > > > > We are on a budget, and a prebuilt micro hydro > >> > > >> > > unit > >> > > >> > > > > is out of the > >> > > >> > > > > question, at least the ones I've seen so far > >> > > >> > > ($1,000 > >> > > >> > > > > and up). > >> > > >> > > > > > >> > > >> > > > > If we were to use an off the shelf auto/truck > >> > > >> > > > > alternator w/ brushes, > >> > > >> > > > > how long can we expect the brushes to last > >> > > >> > > running > >> > > >> > > > > 24/7? Are PM > >> > > >> > > > > alternators available, and how pricey are they? > >> > > >> > > > > > >> > > >> > > > > My second dilemma is predicting the best turbine > >> > > >> > > > > type and size, and > >> > > >> > > > > pulley ratio to obtain the highest RPM at the > >> > > >> > > > > alternator with the > >> > > >> > > > > available water flow. Is there a method to help > >> > > >> > > make > >> > > >> > > > > these decisions? > >> > > >> > > > > If we fabricate some sort of squirrel cage type > >> > > >> > > > > turbine, how do I > >> > > >> > > > > decide the optimum radius of the unit? > >> > > >> > > > > > >> > > >> > > > > Thanks so much for any help! > >> > > >> > > > > Bill > > > > ------------------------ Yahoo! Groups Sponsor --------------------~--> Get fast access to your favorite Yahoo! Groups. Make Yahoo! your home page http://us.click.yahoo.com/dpRU5A/wUILAA/yQLSAA/FGYolB/TM --------------------------------------------------------------------~-> 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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