Autotransformer to run Well Pump? - Page 2

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


Yes, but I had the luxury of choosing my pump after knowing the
capability of my solar system. I have a Grundfos SQE pump, which is
electronically controlled from above ground. I can set the
speed/output/current draw to match my available power - maximum when
the genset is running, or lower to stay within my solar budget. It
also has "soft start", so there is no surge and the current ramps up
gradually over ten seconds.

The SQEs are 3" diameter with 1" output pipe, and can sometimes be
dropped down beside your existing pump. One person can actually pull
an SQE from 180' by hand. If there is any chance you could fit one in
your well, I'd recommend adding one, rather than struggling to run a
2HP behemoth on solar.

The only reason mine is 240V is the distance I had to run from the
power source. The transformer was far cheaper than the cost of the
larger wire to run a 120V pump.

...

The critical value is the NEMA code of your pump motor - see Chart A
at:
<http://www.gillettegenerators.com/sizing/sizing03.html>

My 1HP table saw, for instance, has a 'K' motor, and starts fine on my
SW4024 or 5KW Onan. A friend's 1HP saw has an 'M' motor that kills
either dead instantly. Same power when running, but the starting surge
on the higher letters goes way up.

As for VA vs watts, search for "power factor". Another advantage of
the SQE's electronics - it is power factor corrected so the VA is the
same as the watt draw.

Loren

  Loren Amelang wrote:


Isn't it easier (and probably cheaper) just to use a DC pump, which runs
slower when there's less voltage?  My pump always draws to match the
available power.  The one on my DHW solar panel works the same way.
--
derek

 On Thu, 22 Mar 2007 20:40:19 -0300, Derek Broughton



DC submersibles are expensive, and generally limited to about 500' of
head. Even when they fit the application, they can sometimes be hard
to justify over a conventional submersible if one isn't pumping too
much water.

Wayne

 

I have about 665' of head.  I seem to recall seeing DC pumps that could do
that but they were expensive and, if I remember correctly, needed to be
yanked out once a year to replace the brushes.  Still in the back of my mind
though...

 Ulysses wrote:


Yikes!  Sorry, I hadn't noted the depth.  I though going down 300' for mine
was deep.  We actually paid more than we needed because we thought we'd be
pumping 300'.  It turned out that the well will (just barely) overflow, so
the pump's only down 50'.
--
derek