[RE-wrenches] Grundfos SQ Flex

[Nathan Jones]

Kirpal,
I have several of these units operating with pressure tanks with no problems there. Glad to see the pressure swich being used as disconnect. We have had multiple installs where the CU200 command to stop pumping was ignored by the pump and pressure relief protection saved the day. The DC will burn the points off the pressure switch in short order if it is not DC rated. Square D makes a line of heavy duty switches with this capability. I have an idea of what happens on the current carrying wires during the switch from AC to DC but will let someone who knows for sure educate me also. If you have problems finding the pressure switch, should you need one let me know. I've got the series numbers with all the range of pressure set points back at the office.
Nathan Jones
Power Source Solar
417 827 0738

On Wed Apr 6th, 2011 3:55 PM CDT Kirpal Khalsa wrote:

>Hi all....so I have a pumping project using a grundfos SQ Flex pump....It
>will operate on the grid when grid is present and then switch back to solar
>ready if the grid power should fail.....here is the set up...
>5-Sanyo HIT 220's Vmp non temp adjusted is 213VDC
>Pump is SQFlex 16 SQF-10 will have CU 200 controller and IO101 AC input
>box....
>
>System has a pressure tank and pressure switch which will be used instead of
>float switch as there is no storage tank at or above ground level....
>This system is a retrofit project to an existing well pumping system......
>Here is my questions:
>1. Pump and CU 200 controller are rated for upto 300VDC but IO 101
>Controller is only rated for 225VDC.....is that open circuit or max power on
>the modules....
>2. The Grundfos wiring diagrams only show 2 wires and a ground leaving the
>IO101 going to the CU200.....What is happening when there is 240VAC
>supplying the system and what happens when it switches back to DC how is the
>power transmitted on those wires?  What happens to the second leg of the
>240VAC generator/grid input?
>3. Has anyone done one of these Grundos SQFlex back up water pumping systems
>connected to a pressure tank and did it operate as expected?
>Grundfos does not offer tech support.......that is kind of a bummer....
>Thanks for any advice or help....
>
>
>--
>Sunny Regards,
>Kirpal Khalsa
>NABCEP Certified Solar PV Installer
>Renewable Energy Systems
>www.oregonsolarworks.com
>541-218-0201 m
>541-592-3958 o