Contactor with 120v ac coil / need manual reset in case of power outage

Discussion in 'The Projects Forum' started by Lineout, Aug 8, 2014.

  1. Lineout

    Thread Starter Member

    Nov 20, 2013
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    Is there a manual restart switch based on the power going low ?

    I want to be sure a switch or button has to physically be pushed before
    power can be re established.

    The coil is 120 volts ac.

    What are some good options to handle this ?

    Thanks...
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,542
    2,369
    Yes this is the typical starter contactor device or circuit.
    You place a N.O. aux contact on the contactor in parallel with the start P.B.
    If you lose power the contactor drop out and opens the retaining contact.
    You can also get starter boxes already configured this way.
    Telemecanique wiring diagrams
    Max.
     
    Last edited: Aug 8, 2014
  3. Lineout

    Thread Starter Member

    Nov 20, 2013
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    Thanks,

    What do you mean 'the' start button?
     
  4. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,542
    2,369
    Start, reset, engage N.O. P.B. or what ever you want to call it.
    Max.
     
  5. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,542
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    SeePage 6 fig-2 of the PDF.
    Max.
     
  6. Lineout

    Thread Starter Member

    Nov 20, 2013
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    I'm not being smart, you said 'the' , not sure what you mean.

    The pb is part of the aux or you assume I have one included ?

    I don't understand this at all , I get contactors totally ,not how to
    intergrate a an aux to make sure it doesn't come on when the power is out.

    My pc won't handle a 100 page PDF download .
     
  7. Lineout

    Thread Starter Member

    Nov 20, 2013
    64
    0
    I got it to stop loading, let me look over this page for a minute, thanks...
     
  8. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Your words, 'a switch or button' this is the N.O. P.B. I am referring to, you can also get self contained Starter boxes with start stop and the retaining contact or latch already configured.
    Using separate items, you have to wire it your self, but it is minimal.
    Max.
     
  9. Lineout

    Thread Starter Member

    Nov 20, 2013
    64
    0

    Got it, but I don't understand the diagram in terms of applying it
    to my contactor, the description of what it does is exactly what
    I need.
    This is a jard 17426 that I have right now, not sure I'll find an aux block that mates up.
    I have several of these to hook up , I'd be better off if I could buy the
    completed pkg so I could actually understand how it functions as one unit.
    Is there a specific model that would be an all in one as you mentioned ?

    Thanks....
     
  10. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,542
    2,369
    That is rated a Definite Purpose Contactor intended for HVAC & heavy duty use etc.
    You may not get a self contained unit with that rating, you would have to ask a local electrical supplier that stocks Square-D etc.
    If it has no aux contact and no allowance for one, the alternative is a small auxilliary relay with a contact on it that picks up the coil, the relay would be wired exactly as per the PDF.
    If it is HVAC etc, you most likely have a 12v/24v circuit there you could use for the small aux relay?
    Max.
     
  11. Lineout

    Thread Starter Member

    Nov 20, 2013
    64
    0
    Ok...Thanks,

    I'd have to see one put together to actually understand the whole picture.
    I couldn't make enough sense of the pdf to go buying parts I think
    would achieve what it appears is layed out.

    Until I've seen it , I doubt I'll get the whole picture.

    I might try a 555 in monostable with a P type mosfet or something and go around it another way.

    Thanks!!
     
  12. Lineout

    Thread Starter Member

    Nov 20, 2013
    64
    0
    Yep, definite purpose , a bit of over kill for the equipment but very affordable.
    I found some from China that were awesome , but shipping dates were way to far out.
     
  13. inwo

    Well-Known Member

    Nov 7, 2013
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  14. Lineout

    Thread Starter Member

    Nov 20, 2013
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  15. inwo

    Well-Known Member

    Nov 7, 2013
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    You could also use the 3 pole version, and use one pole for an aux. contact.
     
  16. BillB3857

    Senior Member

    Feb 28, 2009
    2,400
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    Or you could just do this......
     
  17. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,542
    2,369
    A small aux relay as per #10 is easier than 555 & mosfets etc?
    Or as inwo mentions get the 3 pole version.
    Max.
     
  18. inwo

    Well-Known Member

    Nov 7, 2013
    2,433
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    Could you explain the control circuit and load?

    There may be other solutions.

    The control relay solution suggested, may even be required, if the contactor is automatically controlled.

    Or for certain load, from the same supply as control, two poles may be enough.
     
  19. Lineout

    Thread Starter Member

    Nov 20, 2013
    64
    0
    A two pole contactor with a 120 volt coil / turns on a 220v table saw.

    When the power goes out in the building , the coil will de energize, but when the power comes back on the coil will re energize and turn on the circuit.

    I need a manual reset , so the coil cannot be energized unless someone
    physically pushes a reset button/switch following any power outage.

    I'm great with contactors, but have no clue how an auxillary contact block works.
     
  20. inwo

    Well-Known Member

    Nov 7, 2013
    2,433
    315
    So is this what you have now?
    Or do you use a transformer for the 120vac coil?
     
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