ERIC: No, better understand how the GRID connected motor converts to an induction generator. The RPM of the motor as fed by the Turbine needs to be higher than the motor's RPM as a motor by the Slip %, when the AC is applied to the motor, IT starts producing energy in phase with the GRID and controlled by the GRID> You have a small hydro turbine power that is around or less than 1.2 KW .
ALSO, you are not producing AC independent from the GRID, the GRID is producing the magnetic bias to the motor, so the motor is synchronized to the GRID in frequency and phase. You are referring to your initial idea -- YES -- problematic Regards Nando ----- Original Message ----- From: "Eric Kunz" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Tuesday, May 03, 2005 11:18 AM Subject: Re: [microhydro] Grid-Tie Inverter with Induction Motor as Generator > Thanks for the reply. > > "Pumping" AC directly to the Grid is not a trivial > task for any micro-hydro application and it is illegal > here. A Phase Control/Flow Control system would be > EXTREMELY difficult to develop to allow a true AC > Direct-To-Grid system. A couple rpm drift would cause > a short circuit. > Additionally, these new high voltage DC Grid-Tie > Inverters are amazing and very safe as well. They are > UL approved and run at about 93%-95% efficiency and > were originally designed for PV Solar Arrays. > > > > --- H2MJD <[EMAIL PROTECTED]> wrote: > > Hello Eric, > > > > I think its a great idea. > > > > Back in 1985 i installed a unit quite similar to > > your site. The head was only about 80 ft if i > > remember correctly but the flow rates were very > > close. Anyway we used a small 4.5 inch pelton runner > > directly mounted to a 1800 rpm 3 phase induction > > motor shaft wired for 220 v and two nozzles. We > > excited the gen with three small caps then rectified > > the output and were rewarded with about 140vdc. > > Almost perfect for charging a 120 v set of > > batteries. From which the owner ran regular light > > bulbs and 120vdc motors for his woodworking shop. > > The system was very simple and robust....just add > > water and watch it run and run and run. His only > > maintanance was bearing replacement every five years > > or so....oh and once a weld broke on the motor > > rotor. > > > > If the windy boy allows for mppt i think the system > > would be even better. > > > > The one question i have is....why use a windy boy at > > all......just wire the 3phase motor for single phase > > and pump it directly into the grid.........mark > > ----- Original Message ----- > > From: ericfusa > > To: [email protected] > > Sent: Monday, May 02, 2005 6:45 PM > > Subject: [microhydro] Grid-Tie Inverter with > > Induction Motor as Generator > > > > > > Hello, > > > > I am new to the group. > > I have a potential microhydro site of about: > > -100 ft head > > -100 gpm(Winter) to 30gpm(Summer). > > -I plan to use 3" or 4" pvc piping with about a > > 375 to 400 foot run > > of the river. > > -Pelton or Turgo Impact Turbine > > > > I had the idea to use a 3ph/4 pole 220VAC > > Induction Motor as a > > Generator and connect the rectified/smoothed > > output directly to a > > Grid Tie Inverter. I noticed that SMA makes a > > version of their > > popular Sunny Boy Inverters for Wind Generation > > using the same > > concept. SMA calls this version a Windy Boy. > > According to SMA, this > > inverter is designed to allow Maximum Power Point > > Tracking(MPPT) for > > an induction motor driven as a generator for Wind > > Power applications. > > > > According to my calculations, the induction > > generator should be able > > to output a rectified voltage of about 310V DC or > > higher which is > > perfect fo the inverter. > > > > Questions: > > > > Does anyone have any experience with this type of > > grid-tie/net- > > metering system? It seems quite simple and > > efficient to me but, I am > > a micro-hydro newbie and may be making major > > estimation errors. > > > > I've been told that a PM Generator is more > > efficient than a driven > > 3ph induction motor but, I feel that the overall > > efficiency of the > > system should still be quite good and simple. > > > > Any comments or critisism would be greatly > > appreciated and will > > surely save me time, frustration, and money. > > > > Kind Regards, > > Eric Kunz > > Camas, WA USA > > > > > > > > > > > > > > > > > > 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 > > > > a.. To visit your group on the web, go to: > > http://groups.yahoo.com/group/microhydro/ > > > > b.. To unsubscribe from this group, send an > > email to: > > [EMAIL PROTECTED] > > > > c.. Your use of Yahoo! Groups is subject to the > > Yahoo! Terms of Service. > > > > > > > > [Non-text portions of this message have been > > removed] > > > > > > > > > > > > Kind Regards, > Eric R. Kunz - Furuno USA Inc., Senior Product Manager > > ******************************** > Furuno USA Inc. > 4400 NW Pacific Rim Blvd. > Camas, WA 98607 USA > Tel. 360-834-9300 > Fax. 360-833-5142 > email: [EMAIL PROTECTED] > web: www.furuno.com > ******************************** > > __________________________________________________ > Do You Yahoo!? > Tired of spam? Yahoo! Mail has the best spam protection around > http://mail.yahoo.com > > > > > > 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! 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