Design guidance request [RE-wrenches]
Ray Walters
walters at taosnet.com
Wed Jan 3 20:45:35 PST 2007
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HI Allan;
We've got a Bergy XL.1 that we're running about 400 ft. Extra voltage
drop isn't as big an issue with those. They all are 24 volt Dc at the
batteries, but are a variable ac voltage from the wind turbine to the
controller. At one time, I had a problem with actually making too much
power from the windmill (over 1700 watts from 1000 watt rated unit)
which was causing nuisance tripping of the 60 amp breaker. Bergey sent
me a huge 1/2 ohm resistor (1000 watt rating) to install in line between
the turbine and controller. Since then, I 've always undersized the
cables a bit more to simulate the resistor. Since the turbine makes way
over rated power, I've never had any complaints about line losses, and
nuisance tripping is cured too. Also, Bergey has been really good to
deal with.
I had another XL.1 last summer that actually took a direct lightning
strike (burn marks on the cowling) and it just needed a new rectifier
and main fuse.
When doing the line loss calculations, I usually look at power at avg.
speed (maybe 12 to 15 mph here) instead of getting worried about losses
at full power. It seems the batteries top off fairly quickly in high
winds, and then all that extra power becomes a liability in an off grid
system.
Ray
Allan Sindelar wrote:
>Wrenches,
>We do relatively little off-grid wind; mostly keeping a few of Windy's old
>Jake installations from the 80s spinning. Santa Fe County has a 35' height
>restriction and lots of sun, so we don't get too many wind installations.
>Today I got a lead call that I want to be prepared for (coming in on Friday)
>and I am requesting a little advice.
>
>The customer planned a ranch for grid extension, 1 3/4 miles at $48K and
>then couldn't get the easement. He thinks he needs about a 3kW array, but
>has also asked about wind. He has an existing water pumping windmill on a
>tower he says is at least 80'; so far so good. The water pumper served this
>ranch for years, but is disabled now, replaced by a 2HP submersible pump
>that runs off a welder/generator to fill a stock tank from time to time. The
>windmill tower is 300-350' from the house and the rest of the power system,
>and he asked if he could use it for a wind charger at that distance. I was
>generally encouraging, but need to be better prepared.
>
>>From this basic information, it sounds like a hybrid PV/wind would be a good
>bet. My first idea is a Windy Boy AC-coupled to a Sunny Island (or Outback),
>along with sufficient and redundant dump load to prevent overcharging and
>overspeeding. Is this a reasonable approach?
>
>But my main question is: what's a better way? Assuming we want to use the
>existing water pumper tower (and should we?), how should we set up for an
>assumed 400' run?
>
>Thanks in advance,
>Allan at Positive Energy
>
>
>
>
>
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