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Solenoid amperes ???

Discussion in 'General Electronics Discussion' started by abuhafss, Jun 29, 2018.

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  1. abuhafss

    abuhafss

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    Aug 3, 2010
    Hi

    How can we determine the amperes required for a coil to energize its coil and to hold the piston?

    I have Chinese 12V Solenoid valves but without label.
    I need to select proper power supply for them.

    Valve.jpg
     
  2. dave9

    dave9

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    Mar 5, 2017
    Either find an identical looking Chinese solenoid and get the specs from that, or implement that one while connected to a bench supply capable of current limiting to see at what point the solenoid is overcome by the pressure of what it is valving, then add a little margin.

    On the other hand, you could consider the small size and thermal density while powered, assuming it is rated for continuous duty (or you intend it for that purpose). It is hard to "assume" from a picture with nothing else in it to determine scale, but supposing the pipe diameter is no larger than 1" to judge scale, I would guess that it shouldn't need 2A, probably around 1A to 1.5A and a 3A PSU would be plenty with some margin.
     
  3. davenn

    davenn Moderator

    13,617
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    Sep 5, 2009

    isn't that a label I can see on the bottom side ??

    if not, my other comment would be …. you bought a solenoid without knowing the spec's ??
    go back to where you bought it
     
    Tha fios agaibh likes this.
  4. Minder

    Minder

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    Apr 24, 2015
    So do you know if it is AC or DC? , there is alot of difference.
    Easy If DC just measure the resistance.
    I never use AC solenoids if at all possible, DC are much more reliable.
    M.
     
  5. abuhafss

    abuhafss

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    Aug 3, 2010
    I am sorry, I should have mentioned that.
    The pipe Dia is 1/2 inch and it is normally closed.
     
  6. abuhafss

    abuhafss

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    Aug 3, 2010
    I bought it from a local hardware store.
    He confirmed that there is no label on it but it is 12V DC. I have also checked it is working on 12V but I need to know the correct amperes.
     
  7. hevans1944

    hevans1944 Hop - AC8NS

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    Jun 21, 2012
    The "correct amperes" is whatever the solenoid current is when 12 V DC is applied. Put a multimeter in series with the coil and select the 10 A range. Energize the coil from a 12 V DC supply (such as a fully charged automobile battery) and observe how much current is supplied to the coil. Alternatively, measure the un-powered coil resistance in ohms with a multimeter and divide this into 12. The quotient is the current in amperes required to operate the solenoid. See @Minder's post #4 above.

    Is the photo you posted the actual part that you have? If so, please photograph the round metal tag underneath the nut and let us see what is written there. If not, why did you post this photo?
     
  8. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,411
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    Jan 21, 2010
    If you're just interested so you can make sure your power supply is capable of driving it, OK. But remember that your power supply only needs to be able to supply enough current (not the exact current).

    If the total load is 2.5A, a power supply capable of 2.5A or more is OK (personally I'd leave some breathing room -- Say 25% to 50% more capacity in the power supply than the total current drawn.

    Do what my learned colleague above suggests to determine the actual current drawn.
     
    abuhafss likes this.
  9. Minder

    Minder

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    Apr 24, 2015
    If it is a DC coil measure the resistance and it will tell you, (Ohms Law!) the current for a typical DC sol of that size is around 1a to 1.5a
    If it is very low resistance then it is the AC variety.
    Also if switching it electronically, you will need a BEMF diode across the coil, in4002,,-7 etc
    M.
     
    Last edited: Jun 30, 2018
  10. abuhafss

    abuhafss

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    Aug 3, 2010
    No, I just copied it from the net (to save time).
    Both of my parts are almost identical to it. except that both have plain round tag without anything mentioned.
     
  11. abuhafss

    abuhafss

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    Aug 3, 2010
    Bundle of thanks to all of you for sparing moments for me.
     
  12. davenn

    davenn Moderator

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    Sep 5, 2009
    so that photo you supplied ISNT you unit … can you see how that doesn't help us help you
    It is always good to supply the correct info :)
     
  13. dave9

    dave9

    930
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    Mar 5, 2017
    Well, IF that's an accurate photo of his, it might help because I found some info on the one pictured.

    https://www.m.nu/vatten/brass-liquid-solenoid-valve-12v-1-2-npt


    [​IMG]
     
    abuhafss and hevans1944 like this.
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