Kirpal,
For the occasional odd high-current DC contactor, I like MDI. They made
the mercury displacement contactors used years ago in the Ananda/APT
Powercenters. Check out http://www.mdius.com/relays.php#High_Voltage to
see if they have anything you can use.
Allan
Kirpal Khalsa wrote:
Hi All....thanks for the good feedback on this water
pumping system. Many good ideas....It looks like this is a system
which can be done. I will be looking for a relay that will have the
necessary voltage characteristics which will have ~200VDC on one side
being normally closed and 240VAC on the other side, normally open.
Mark, Allan.....I am looking at the Grundfos SQFlex Battery Back up
system brochure and it shows a SQFlex system running with a pressure
tank in their example system. Additionally they brochure goes on to
say that "the CU 200 Controller has terminals for a pressure switch,
which will control the pump's on/off operation via the pressure in the
storage tank. The pressure switch should be of a normally open
configuration, where the contacts within the switch are in the open
position when the pressure is below the maximum set-point. When the
pressure in the system rises to the maximum desired pressure, the
contacts will close signaling the pump to shut off." In researching
further it looks like the float terminals in the CU 200 controller are
able to be used for either a float switch or pressure switch.
I don't have any experience running a pressure tank in line with the
output of the system but I can't see why as Allan pointed out that it
would know the difference between 40PSI in a pressure tank or an
additional 100' of head. I think that it is important to recognize the
additional head ( due to the pressure tank) that will be present and to
take that into consideration when sizing the array for the desired
amount of gpm production.
If anyone has any recommendations for a relay or other switch which can
handle 200VDC and 240VAC I would be grateful.....
Cheers,
--
Sunny Regards,
Kirpal Khalsa
NABCEP Certified Solar PV Installer
Renewable Energy Systems
www.oregonsolarworks.com
541-218-0201 m
541-592-3958 o
On Mon, May 24, 2010 at 2:42 PM, Mark
Dickson <m...@oasismontana.com>
wrote:
Allan,
This is all
Dwight at Genpro could tell
me. . .sorry to be vague! I agree, it seems like it would not know the
difference.
I
would love to shed
some light, however this was shared with us at the NGWA show by a
Grundfos
Engineer. It has brochursomething to do with the thrust load bearing
on a
them. Lorentz has two I believe Grundfos has one.
Best
regards,
Mark
Dickson,
NABCEP
Certified Solar
PV Installer ™
Oasis
Montana
Inc.
Mark,
Your message gave me pause, as I just last week specified this setup,
so I
checked into it with our Grundfos rep. He said he had never heard
anything
recommending against the flex in a pressure system. He said the SQF
doesn't
know the difference between 40 psi and 100' of head. At the end of the
day the
pump just stops.
He did make a point of emphasizing the need for pressure relief valves,
as the
helical rotor models can overpressure a system.
Could you check with your distributor about this and post the reason
you're
given, please?
Allan
Mark Dickson wrote:
Our Grundfos
pump distributor has always warned against using
the SQF pumps in pressure pumping situations. I can’t quite
remember why, but you may want to check into that. The Lorentz HR’s
have been the choice in these situations.
Best
regards,
Mark
Dickson,
NABCEP
Certified Solar PV
Installer ™
Oasis
Montana
Inc.
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