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Pump start wire toooo long

Discussion in 'Irrigation' started by Let-it-mow!, May 22, 2007.

  1. Let-it-mow!

    Let-it-mow! LawnSite Member
    Messages: 91

    Here's a system I'm trying to get going.

    The irrigation controller is located at the field being irrigated. The booster pump is far from the field being irrigated.

    There is an existing 2-conductor wire that runs from the controller to the booster pump to operate the pump. This wire runs several hundred feet under a paved parking lot so replacing the wire would be a bigger job than I want to do.

    When the timer calls for the pump to start, I get 27V at the pump start terminals of the controller. At the other end of these undersized wires, I get only 9 volts which isn't enough to close the relay to start the pump.

    Now, I could swap the relay for a 12V relay and probably get buy except that there is a second timer that also operates this pump from a different location and the second pump is close enough to provide the 24V the relay needs. So the 24V relay must stay.

    Here's two Rube Goldberg ideas I've come up with but I'd like something less home-made.

    Idea 1: Install a 50V power supply at the field controller and use a relay to let the controller send 50V from this power supply to the pump. This might get me over the threshold to make this thing operate.

    Idea 2: (Only nerds like me need read on) Install a "full bridge rectifier" at the field controller so I'm sending DC over the wires instead of AC. The pump start relay magnetic winding will provide a large amount of impedence to AC but less so to DC meaning the current in the relay coil should be higher with DC. Higher current means a stronger magnetic field and maybe the relay will close.

    Obviously I'm grasping at straws here. Any good ideas appreciated.
  2. Keith

    Keith LawnSite Gold Member
    Messages: 3,979

    What size is the wire from the controller to the pump start? What controller are you using?
  3. Bigred350

    Bigred350 LawnSite Senior Member
    Messages: 810

    Sounds like the wire is gone bad to me. What size wire do you have. A 18 ga wire should work over 500 ft no problem.
  4. bicmudpuppy

    bicmudpuppy LawnSite Silver Member
    Messages: 2,781

    If your sure you can get a relay that will open and close properly on the 9 or so volts provided, why not use that relay operate a 24v transformer that will fire the pump start? This will allow the other controller to still use the pump start, but work around your wiring problem.
  5. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,582

    Of course, the wiring may degrade further, and make any current workaround obsolete.
  6. Dirty Water

    Dirty Water LawnSite Fanatic
    Messages: 6,794

    If I understand this right, you have a 2 conductor line running from one timer (500' away) that has too much voltage leak/resitance.

    Then you also have another timer that has wire running to this pump start?

    I think Bryan has it right. You already have 110 to the pump, so get another 24 transformer, and use a relay on the 9v or so you get to cycle the 24v to the pump start relay.

    Or if there is a spare wire in the other line coming from the other timer, run constant hot 24v and use the 9v to switch the relay there, so you don't need an extra transformer.
  7. WaterGuru

    WaterGuru LawnSite Member
    from Florida
    Messages: 39

    Yup Yup

    You could always start with a fault locater and see if you can locate the source of the bleed off.
    Any chance of a splice that is not in the asphalt?

    Personally, if the system worked at one time, I would spend sometime trying to find and fix the problem (assuming you have not already wasted countless hours doing so)
  8. bicmudpuppy

    bicmudpuppy LawnSite Silver Member
    Messages: 2,781

    Or fix the problem with programming and sync the two controllers. Use controller B to fire a phantom zone to jazz the pump start, and run controller A in this time frame. Only problem here is if there is no pressure/saftey switch if you don't get the timing right.
  9. Midlo Snow Maker

    Midlo Snow Maker LawnSite Member
    Messages: 183

    trace your wire cut it half way and see what you got, your ideas will probably only work for a short time
  10. Mjtrole

    Mjtrole LawnSite Member
    Messages: 226


    did it get figured out?

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