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Jacarta intelliAmp - Would L & N not cancel each other out?

Discussion in 'Electrics UK' started by eveares, 25 Sep 2017.

  1. eveares

    eveares

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    So I saw this in a magazine at work today:


    The PDF on it is here: http://www.jacarta.com/wp-content/uploads/2016/07/Jacarta-intelliAmp-2016.pdf

    Apparently, it can measure power and current by simply clipping it over an active and already existing 3 core 16A/32A cables! (As in the ones that look like caravan electrical connectors.)

    How does this work as I would have thought the magnetic fields of the Line and Neutral conductors in the cable would cancel each other out, hence why normally you put current clamps just over one current-carrying live cable!?

    Regards: Elliott.
     
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  3. JohnW2

    JohnW2

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    Dunno - I would have thought the same as you, whether it uses inductive coupling or Hall Effect devices.

    Hopefully someone will enlighten us!

    Kind Regards, John
     
  4. aptsys

    aptsys

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    A series of hall effect sensors can measure current in a device like this. I worked on a prototype many years ago but at the time it was cost prohibitive.
     
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  5. JohnW2

    JohnW2

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    Thank - interesting. How does even that work since, just like eveares, I would have thought that the L and N magnetic fields would simply cancel?

    There presumably must be some 'problem' (still cost) since, otherwise, I would have thought that such things would be very common - since it would address the main drawback of 'clamp meters/sensors'.

    Kind Regards, John
     
  6. ban-all-sheds

    ban-all-sheds

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  7. Edddd

    Edddd

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    A cable with parallel cores could be seen as an extremely elongated, single-turn solenoid. So from a position above or below the plane in which the cores lie you would detect a magnetic field.

    Problem is, unlike in a normal clamp meter, you can't capture the flux for accurate measurement by enclosing it with an iron loop. Because as you say, the total flux through any loop around the entire cable is zero. So any measurement from a hall sensor would be highly dependent on its precise position relative to the cores.

    Maybe with an array of hall sensors you can solve this with a function of all the measurements. Or maybe it requires calibration from a known load in every installation. Or maybe it makes assumptions about the physical dimensions of the cable.
     
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  8. JohnW2

    JohnW2

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    Thanks. One interesting point about the 'Specification' in the pdf posted by eveares is the absence of mention of anyhthing to do with accuracy.

    Kind Regards, John
     
  9. winston1

    winston1

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    Even if it can measure current it cannot possibly measure power. To do so it needs to also measure voltage and phase angle neither of which it does.
     
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  11. aptsys

    aptsys

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    On the system I worked on, there was an array of hall effect sensors around the circumference of the clamp. You could then simultaneously sample all of the sensors and evaluate where the individual cores of the cable were and then use an algorithm to calculate the current flowing through the cable.
     
  12. Edddd

    Edddd

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    You could measure the phase of the voltage by capacitance. Place conductors on either 'side' of the cable and measure the electrostatically-induced voltage between them. Measuring the amplitude of the voltage would be more difficult because of the cable size/placement/arrangement uncertainties.

    Or maybe there is a plug-in unit that measures voltage centrally for multiple clamp sensors: 'Multiple sensors can be monitored from a single monitoring device'
     
  13. JohnW2

    JohnW2

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    Very true, but it doesn't claim to measure anything other than 'true RMS current', so your comment is not really relevant to this product.

    Kind Regards, John
     
  14. JohnW2

    JohnW2

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    AS I've just written to winston, it doesn't claim to measure anything other than current.

    Kind Regards, John
     
  15. Edddd

    Edddd

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    Sounds clever! Did it work, despite the cost?
     
  16. EFLImpudence

    EFLImpudence

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    I am puzzled why it states this:

    upload_2017-9-26_12-24-7.png

    and then this:

    upload_2017-9-26_12-25-12.png
     
  17. ban-all-sheds

    ban-all-sheds

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    But the cores do not lie in a plane.
     
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