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Discussion in 'Misc Electronics' started by hungry1, May 27, 2004.

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  1. hungry1

    hungry1 Guest

    Is it possible to make a debouncer circuit for pressure switch
    contactors that operate on 240v?
  2. hungry1

    hungry1 Guest

    Trying to save the contacts, they get a LOT of use, they burn out very
    rapidly from arcing.
    The water pump is in use 24-7-365.
    Any ideas? I live on an island where there is not too much stuff available.)
  3. John G

    John G Guest

    If you could just double the hysteresis of the loop you
    would double the life of the contacts.

    No knowing how your pump is fitted up I can only suggest and
    you can turn it into practice if possible..
    Double the distance between turn off and turn on by whatever
    mechanical means or,
    Double the size of the reservoir if that is where the switch
    Whatever you do increase the length of each ON cycle and
    thereby increase the OFF time.
    A Solid-state relay, as already suggested, would reduce the
    current thru the contacts and thereby reduce the arcing
    again increasing the contact life.
  4. Paul Guy

    Paul Guy Guest

    If this is for a water supply, I'd check to see if your air
    reservoir has run down (causing rapid on-off of water pump). There
    should be a few adjustments to set the pump-on to pump-off
    differential on your pressure sensor. They may be set too close. For
    house water pumps, the differential is often about 20% or more
    differential (10-15 psi differential at 50 psi delivered).
    How long does your pressure switch last? The water pump controllers
    cost $20-30 (here), and I find they last 5 -15 years. The water is
    full of iron here, they usually jam full of sediment after that time,
    and seldom fail from contact wear.
    You can also put in snubbers to reduce the arcing generated by the
    inductive kickback of the motor when the contacts open. I've seen them
    for low powered circuits, but not for something like a 1/2HP motor. In
    any case, I wouldn't trust them, since if they fail, they'd probably
    catch on fire. I would imagine you could get MOV's that are rated for
    this application, and place them across the load. You need something
    to dissipate the energy "dumped" from the inductance of the motor when
    the contactor opens. I wouldn't trust MOV's either.... they start to
    change after a while, especially if you give them a lot of transients
    like you'd see in this application.
    From what I remember, you need SOME arcing to keep the contacts
    clean. Power relay contacts use a cadmium alloy that flash clears the
    gunk on the contacts when they arc. This gives power relays a long
    contact life, they'd otherwise gunk up and and give intermittant
    connections, or worse, give a bad connection, fry the contacts right
    off, and start a fire.

    Somewhere in the Nova Scotia fog
    ANTISPAM - Please remove the m's in my email address
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