Current sensing device

Discussion in 'The Projects Forum' started by ian.blue, Dec 7, 2011.

  1. ian.blue

    Thread Starter Member

    Jul 12, 2011
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    I am looking for a way of sensing current flow in an 2 wire 250volt AC circuit.
    the flow would be about 30amps and I would need a digital signal when current flows.
    I do not want to tap into the live conductors but could this current be detected through the insulation?
     
  2. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    Yes, A Hall effect type sensor can be used.

    Is this a temporary or permanent installation?

    Clamp ammeters that can measure DC use the hall effect for measurements, or you can order current sensors that are literally snapped around one wire and you get a tap out, usually 0.01-.1V/amp or less.
     
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  3. ian.blue

    Thread Starter Member

    Jul 12, 2011
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    This is intended as permanent arrangement merely to indicate digitally that the 30amp current is flowing.
    You wouldn't have a ref no for a Hall effect sensor would you?
     
  4. strantor

    AAC Fanatic!

    Oct 3, 2010
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    when you say digitally, do you need the signal to go to a PLC or what? is just an LED ok? Check these out; I use them to indicate if my heater elements are in tact. its just a little deal you slip over the wire and the LED comes on if current is flowing. super simple
     
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  5. ian.blue

    Thread Starter Member

    Jul 12, 2011
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    Well thank you. These are so cute! What a great little product. I would never have found these in a month of Sundays. I love them.
    Unfortunately I need an output which I can use to switch on a small load.
    But I will order a couple of these for other uses anyway.
     
  6. wmodavis

    Well-Known Member

    Oct 23, 2010
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    You might also look at the
    Allegro
    ® ACS714.
     
  7. hgmjr

    Moderator

    Jan 28, 2005
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    This device requires that the conductor carrying the current to be monitored be directly connected to the device. That requirement is counter to the poster's request for a solution that does not involve placing the monitoring device in-line with the current path. The poster is looking for a non-invasive current monitor technique.

    hgmjr
     
  8. wmodavis

    Well-Known Member

    Oct 23, 2010
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    I guess I overlooked that part. It is an interesting chip however for several projects I'm thinking of.
     
  9. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    Here is a panel mount 0-500A permanent mount meter (needs power supply), uses inductive pickup.

    DigiKey has them for $72

    Here is a Hall Sensor with open output Check the datasheet to see if that is what you are looking for.

    I'm unsure what you need on the output side,the top one has a display, the bottom one is a current, needs +-15V supply.
     
    Last edited: Dec 7, 2011
  10. crobertsbmw

    New Member

    Sep 7, 2011
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    I'm looking for almost the exact same thing. A small IC which can be used to detect current. I want a 3volt output when there is current (5-40 amps @ 220ac) and a 0v output when it isn't. But I am going to mount it on a PC board with a ton of other stuff too...

    I think the Allegro is exactly what I need.
     
    Last edited: Dec 9, 2011
  11. tracecom

    AAC Fanatic!

    Apr 16, 2010
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    You could order one with a white LED, place an LDR or another LED facing it. The LDR would change resistance when the source LED came on. An LED facing the source LED would actually generate a small current. Either way, you have double isolation from the mains line.
     
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  12. strantor

    AAC Fanatic!

    Oct 3, 2010
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    true. I've made crude optoisolators like this before, with an LED and a LDR shrinkwrapped together
     
  13. wayneh

    Expert

    Sep 9, 2010
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    You might try hacking one of these. It's $6 tool that I think will detect a hot circuit. I recently bought a fancier version, and it works great.
     
  14. ian.blue

    Thread Starter Member

    Jul 12, 2011
    31
    2
  15. ian.blue

    Thread Starter Member

    Jul 12, 2011
    31
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    Just like to thank everyone for their interest and help.
    What a friendly forum this is!
     
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