I may well be needing a new solar direct pump but I don't know just yet, that's where you come in.  First off when I purchased this land the pump was installed and operating fine.  Three days ago it just quit.  I have some technical skills and have installed my own solar/wind battery system but I'm no "pump guy".  I have no confidence regarding the local techs, I know they will be learning on my expense, it's best I learn.  Here is the deal.

  • Static Head  120meters
  • Solar array 14-100watt, Vmp=18VDC,  1400 watts wired as 120volts at 11amps.
  • Pump....some Chinese..very cheap..110VDC, capable of 140meter head, 1000watt capacity. Apperantly  brushless.
  • Controller...came with the pump...says do not exceed 150VDC, 110VDC is checked on the front and I have no manual....welcome to my Mexican world. 

I opened the controller and started testing stuff.

  1. Internally it had a 30amp auto fuse...Tested fine.
  2. Turned everything on and got no potential difference between array + and - where the array enters the controller.
  3. Disconnected the array from the controller.  Potential difference now shows 120Volts.
  4. I figured the controller was shorting the array so I disconnected the pump from the array.  There are 3 cables marked on the controller as U, V and W.  I have no idea which is +, - or ground to the pump as the wires have no color coding....Mexico... Now I tested the 3 disconnected pump cables for continuity. ALL THREE LINES SHOWED CONTINUITY with each other! *Is that a sign the pump is fried?? or is it normal? 
Then I put it back together and called you this morning.

Before I buy a new pump/controller my 3 questions are.  
A) Is it normal for a DC brushless pump to show continuity between its 3 cables when disconnected from the controller.
   IF NO, well it's new pump time.
   IF Yes, B) Can I test to see if the pump is working and if the controller is toast by connecting the array directly to the pump in strong sun light?
C) Do you have any trick for testing which wire is +, - or ground on a pump 120 meters in a hole with no color designation on the cables?  The pump is on a metal pipe.  Any idea what U, V or W would indicate on the controller where the pump id connected?

If I can't get to the bottom of this and I need to buy a new pump I was thinking Grunfos SQFlex, would you agree.  Thanks for your time, Brian Richards

Comments

Richard,Trace the three wires from the pump back to the controller. Then trace them through the controller. If one of them is grounded and the positive wire is showing continuity through the ground, then most likely there is a melted board on the motor.
Greentech Renewables is well-equipped to handle solar questions - but I suggest you post a similar question on the site of a water-pumping specialty forum or just ask them directly.
Try: Oasis





Submitted
12 years 8 months ago
Asked by
Brian Richards
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