Autotransformer to run Well Pump? - Page 5

 



probably

different

My wife said she may have that info at our store and she'll check tomorrow.
I'm pretty darn sure it's 2 HP.  I doubt my 9 HP 4200 watt generator would
even handle a 3 HP pump.  But we'll see... maybe I have a magic pump.  I
built a RAM pump that I had in my creek here before I got my well drilled
and it's hard to believe (for me anyway) that *it* worked.  Things like that
give me ideas...




I'm a little doubtful about the inverter setup being the best solution but
I'm willing to make a few sacrifices if it means using a generator less.
I've been living with them (and for them) for nearly six years and I'm kinda
sick of them.  Right now I have a dead Coleman, a Homelite/Tecumseh waiting
for head repair, a Honda waiting for a new governor gear, two eu2000s that
need new engines but there aren't any.  The only ones that work right now
are the cheap Chinese things from the auto parts store.  Matter-of-fact in
some ways I like the 2000 watt cheapo better than the eu2000.  If they keep
selling them for $200 then I don't have too much to worry about.  Only time
will tell how long it will last but looking at the diagrams it sure is built
exactly like a Honda GX engine.  I've not had the pleasure of taking one
apart yet so the quality of the engine parts is still a mystery.  But it
burns no oil and the oil looks good after 50 hours.


somewhere

When walking up my hill you are very aware that you are walking uphill so I
guess it is fairly steep.  Are you also using 1 1/4" for the run down from
the tank?   I'm getting 21 psi with my 55 gallon barrel on the hill with
1/2" poly tubing and it's enough to take a decent shower and activate the
valve on the washing machine which supposedly needs 22 psi just to open.
I'm expecting that using 1 1/4" pipe along with more height is going to be a
really big difference for me.



"power

I've never watched to see if the water level drops when the pump is on.  I
wondered about it but it didn't seem to be an issue unless I try using a
surface pump or something like that.  I suspect my well is underrated at 20
gpm.  Some of my neighbors claim 80 gpm or more.  Not bad for being in the
desert.

 

On Sun, 25 Mar 2007 22:34:54 -0800, "Ulysses"


If it were me I'd power the pump off the inverter if reasonably
possible. But if that proves too expensive, then using a generator for
90 minutes a week (200+ gallons per day) is certainly practical. We
use a DC backup generator. Everything runs off the inverters, but if
necessary, the generator can fully or partially power loads without
the inverter needing to switch the generator feed in and out.


If you're going up 8 inches for every foot you walk, then that's way
beyond "gently rolling", and there certainly couldn't be any hill
"awareness" issues.  ;-)

Let's compare.... the walk up to our tank is 800', during which you
climb 100'. That's a 12.5% slope, about 7 degrees. Walking it will get
most people puffing in a fairly short distance, and there's no doubt
it's a hill. From a standing start, a car coasting down that slope
will hit perhaps 50 mph in 1500'. On highways, lesser grades of
extended distance are often accompanied by runaway-truck ramps. From
what you've written, your hill (in round numbers) is a 600' walk, and
one climbs 400'. That would be more like 67% and 34 degrees. Some
backhoe operators get pretty nervous about working on such slopes -
for good reason. Here's a case study of fatality involving a 24 degree
slope http://shippai.jst.go.jp/en/Detail?fn=0&idÍ1000102& , and
here's an illustration of backhoe cg on a 20% slope
http://www.buyerzone.com/industrial/backhoe/rbic-backhoe-loader-tools.html .
Unless your hill is more than three times as steep as that
illustration, then your elevation numbers are at the root of the
mysterious pump performance.


That's a rise of about 48'.


Maximum design flow for a water-conscious home might be 10gpm. If the
run from the tank to the house is say, 200', then using 1" pipe would
result in friction loss of about 5psi
http://homepower.com/files/pipe.pdf . Using 1.25" would reduce the loss
to about 1.5psi. The pipe from the well to the tank (could be the same
pipe for part of the run) is a separate issue, but there again 1.25
should be a reasonable choice.


It's excellent. Although even a half a gallon a minute is 720 gallons
per day, many times what most water-conscious folks would use, and
generally several times more than what most solar folks are willing to
pump with expensive solar power. I've seen a few 1/4gpm wells that the
owners were happy with, and the record that I've seen personally was a
60 gallon *per day* well that cost about $25k. The production was
about what the owner had been hauling, and he was real happy that he
didn't need to do that anymore.

Wayne

 



waiting

I didn't find the pump info yet.  Still looking.




contractor

http://www.buyerzone.com/industrial/backhoe/rbic-backhoe-loader-tools.html .

Um, my slope is much steeper than the one illustrated on that site.  I
remember at one point, when I was calculating how much dirt I would have to
move to make a flat spot for a house, the rise was about 5 or 6 feet going
up the hill about 28 feet.

 

First I was going to go solar, then Edison said it would only be $8000 to
get hooked up to the grid, then it was $23,000, then they couldn't figure
out how to get it to me.... meanwhile I got the well pump expecting to be on
the grid.


I've searched all over the internet many times over for a pump that would
fit in next to the one I have and found nothing.  It looks like I could get
2" or maybe even 2 1/2" between the well and the pump pipe but I think
that's about it.  It's a really good quality pump so I'm trying to utilize
it if possible.

 On Thu, 22 Mar 2007 09:21:12 -0800, "Ulysses"


Any device such as a motor that contains a coil (or a capacitor) draws
its peak current at a different time than the voltage peaks on each
half of the 60 cycle wave.  In fact, a pure inductor draws peak
current when the voltage is zero (90 degrees out of phase).  A pure
inductor draws volt-amps but no watts.

Because of this phase lag, the true power consumed is less than the
apparent power which is simply volts times amps or VA.   True power =
volts * amps * cos(theta) where theta is the phase angle between volts
and amps.  Or more commonly expressed, true power = volts * amps * PF
where PF - power factor - is a number between 0 and 1.  If you have a
Kill-A-Watt, for example, it will display PF directly.

VA or KVA (kilo-volt-amps) is a convenient way to express the capacity
of devices that have to handle reactive current (that is, current in
excess of the real power)  Unless the load is purely resistive (PF=1)
then the VA (volts * amps) is greater than the true power because PF
is always less than 1.


So your pump's VA rating is 240 * 11 = 2640 VA.  That's well within
the rating of that 4000 VA auto-transformer.  Transformers can handle
huge overloads for short period of time, a characteristic of their
construction.  Whatever surge your pump draws will be no problem.


Your pump won't draw that much power.  If the pump has a PF of 0.9
(typically of a fully loaded small motor) then the true power draw in
watts will be 2640 VA * 0.9 = 2376 watts.  If the motor is less than
fully loaded then the PF goes down.  What you'll see at the terminals
is that the power consumption will go down with decreasing load while
the amps stay about the same.  The VA rating is the WORST case that
your generator or inverter will have to supply, ignoring inrush, of
course.


Do you have any other load that justifies that large a system?  If not
then IMO, you're going to great expense just to run that pump from
solar.  Why not just run it from the generator and do everything else
solar?  If you really do only need to run it for 15 minutes a day then
the cost of the generator will be minimal while the cost of the solar
system will be huge for that sort period of operation.

---
John De Armond
See my website for my current email address
http://www.neon-john.com
Cleveland, Occupied TN
All great things are simple and many can be expressed in single words:
Freedom, Justice, Honor, Duty, Mercy, Hope.  -Churchill