Help with pump control circuit

Discussion in 'The Projects Forum' started by Oaksniffer, Apr 2, 2008.

  1. Oaksniffer

    Thread Starter New Member

    Apr 2, 2008
    i have been tasked with making a copy of the below circuit but not being a designer im not sure if it works correctly i would greatly appreciate some feedback and advice if poss.

    It should control two pumps one in a main holding tank (pump a) and one in a resevoir tank (pump b).

    The system needs to be set to run on a timer.

    The holding tank pump fills the resevoir then cuts out once full, the resevoir pump then kicks in and pumps fluid back in to holding tank. Put basicall fluid from holding tank to resevoir then back again.

    Can i use a standard plug in mains timer to control the sequence ?
    I have some DPDT 240v octal relays i want to use up, are the pin numbers the same a standard square base relays as shown in the diagram ?

    Many thanks for any help in advance !
  2. SgtWookie


    Jul 17, 2007
    First, let's review the sequence of events.
    1) Timer closes circuit, supplying power to relay logic.
    2) If the main tank is not full, and there is still fluid in the reservoir, run the main fill pump.
    You wouldn't want to run the main fill pump if the reservoir was out of fluid, would you?
    How do you want to handle a case where there was not enough fluid in the reservoir to fill the main tank, or is this not a problem?
    3) Main fill pump turns off, and it's circuit is disabled for the remainder of the cycle.
    4) While there is still fluid in the main tank, and the reservoir is not filled, run the reservoir fill pump.
    Is there a possibility of the reservoir not being able to hold all of the fluid being transferred back from the main tank?
    5) Reservoir fill pump turns off, and it's circuit is disabled for the remainder of the cycle.
    6) Timer eventually breaks contact, re-setting the relay logic.
    Cycle repeats.

    As far as the relays go, get the manufacturer name and part number from them, and look up the datasheets. It would be a really good idea to check and see if they (or equivalent substitute parts) are still being made, otherwise replacements will be hard to get (and VERY expensive.) If they are obsolete, I strongly recommend that you abandon the idea of using them, because as soon as you run out of them, you'll be re-designing the circuit again.