Daniel
Your getting it but your diagram is still a bit over
simplified. Keep in mind that most commercially
available hydro turbines made for DC battery charging
have alternators on them that produce AC power. They
incorporate the rectifiers and capacitor with them
usually attracted to the outside of the unit.
Also remember it is high voltage that allows for
efficient transport of electricity not whether it is
AC or DC. AC's appeal comes from the fact that it is
easier and more efficient to transform the voltage up
or down. An AC alternator producing power at 220 volts
can transport the power efficiently without
necessitating a large diameter wire. It could then be
transformed to a lower voltage appropriate for
charging your 48 volt system and rectified to DC. If
on the other hand you used a 48 volt AC alternator and
transported it to the house AC, it would require just
as large a wire as a unit producing 48 volts DC. So
the only reason to favor AC transport is to get a high
voltage unit and utilize a transformer at the house to
drop the voltage back down to system voltage. Your
diagram does not reflect this.
Peter N. Allen
--- [email protected] wrote:
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>
>
> There are 6 messages in this issue.
>
> Topics in this digest:
>
> 1. Re: AC vs. DC microhydro
> From: Michael Lawley
> <[EMAIL PROTECTED]>
> 2. Re: AC vs. DC microhydro
> From: BjornOlaf <[EMAIL PROTECTED]>
> 3. Re: Proof of global warming - frogs block
> turbine nozzles
> From: Carlos Bonifetti
> <[EMAIL PROTECTED]>
> 4. Re: AC vs. DC microhydro
> From: Daniel Kim <[EMAIL PROTECTED]>
> 5. Re: AC vs. DC microhydro
> From: Michael McCarrick
> <[EMAIL PROTECTED]>
> 6. site potential?
> From: "steinaman" <[EMAIL PROTECTED]>
>
>
>
________________________________________________________________________
>
________________________________________________________________________
>
> Message: 1
> Date: Fri, 18 Feb 2005 08:41:56 +1300
> From: Michael Lawley <[EMAIL PROTECTED]>
> Subject: Re: AC vs. DC microhydro
>
>
> Hi Daniel
>
> My view is keep it simple
>
> I still do not know your pipe line length? I've
> assumed 1000 ft (300m)
> Flow 4L /s, static head 6.5m, cable length 1000 ft.
> I would recommend you install a farm grade plastic
> pipe of 75mm OD 65mm ID.
> This is very common in NZ and costs about $5 NZ
> ($3.5 US /m)
>
> Using this pipe your running head would be about 30m
> at a flow rate of 4
> L/s. The output power from the turbine would be 570
> Watts.
>
> If you can get a power cable that has a cross
> sectional area of 25-30 mm^2
> per conductor then you will have less than 10% loss
> in the cable.
>
> The turbine voltage will be about 5 volts higher
> than your battery voltage
> due to the cable loss. Cost of cable in NZ from a
> cable surplus yard is
> about $5-6NZ/m ($4 US). You can also use house
> wiring cable, in NZ the 3
> conductors add up to 7.5mm^2 and it costs $1 NZ /m.
> So doing it this way
> would cost you $8 NZ/m ($5.5 US). Find a large
> surplus roll of cable if you
> can.
>
> Power delivered to the batteries would exceed 500W.
> To prevent battery over
> charging simple install a C40 with resistive element
> in your hot water tank
> or air resistive element.
>
> Cost in NZ would be
>
> Turbine $1000
> Cable $1800
> C40 and water element $450
> Plastic pipe 300m long $1500
> Intake strainer (make yourself) $200
>
> Total equipment cost = $5000 NZ = $3500 US.
>
> So your budget of $6,000 is ample and will allow for
> some labour assistance
> in getting the pipe and cable in. We can supply the
> turbine, we have a deal
> for overseas customers where if you buy two turbines
> we will pay the
> airfreight - 2 year warrantee on turbine. You then
> have a spare or can sell
> it to you neighbor.
>
> Regards
>
>
>
> Michael Lawley
> Renewable Energy Engineer
> EcoInnovation
> EcoInn/EcoBach
> 671 Kent Road
> R.D.1
> New Plymouth
> New Zealand
>
> Phone: (NZ) 06 752 2765
> Fax: (NZ) 06 7522768
> Web site: www.ecoinn.co.nz
> email: [EMAIL PROTECTED]
>
>
> ----- Original Message -----
> From: "Daniel Kim" <[EMAIL PROTECTED]>
> To: <[email protected]>
> Sent: Thursday, February 17, 2005 9:22 PM
> 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?
>
=== message truncated ===
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