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When is a spark an arc? OR - When is an arc a spark?

Just watched some chap on the E5 youtube channel visiting Eaton in Austria. Eaton AFDDs have been something of a subject of ridicule in youtubeland, with various respected electrical content providers demonstrating through various real-world means that they don't function. So, off this chap goes to Eaton's HQ in Vienna where they provide him with a aluminium case full of test kit, complete with the Eaton logo and fitted out with various Eaton devices inside.

One of the devices is the Eaton AFFDD which has famously failed to operate on numerous youtube video presentations.

Of course, it trips when tested with their own test kit. After all, no point in trying to sell something which isn't really needed unless you can demonstrate that it actually works, so Eaton helpfully provides the 'right' arc signature so that the device can trip on command in front of all those cynical doubters.


Apparently, all those heath robinson youtubers have been getting it wrong because they have unhelpfully been simulating real world arcing events which these devices won't actually pick up. You see, according to the 'experts' you need an arc instead of a spark to trip the device! What the hell is the difference?


Oh how I laughed! Is this how far they'll go to flog you some old tat you don't really need?

Just how many different arcs and sparks are there out there? Has anyone told David Attenborough of all these new species to explore?


Feel free to jump in!
Parents
  • I don't think "arc" or "spark" are defined in Part 2 definitions of BS7671 (given the time I am cheating and looking at an online pdf copy of the DPC for convenience rather than my official copy which isn't next to me right now).


    It is possible that IEC 62606 (standard for AFDD) has a specific definition for these terms*, if not then for an IEC based standard the definitions in the International Electrotechnical Vocabulary usually apply.

    This can be searched free online here: http://www.electropedia.org/


    Searching for "arc" includes the following result:

    arc
    arcing




    luminous discharge of electricity across an insulating medium, usually accompanied by the partial volatilization of the electrodes

    Note 1 to entry: A complete sinusoidal current half-cycle is not considered to be an arcing half-cycle.






     

    [SOURCE: IEC 62606:2013, 3.1]





    and searching for "spark" includes the following:

     




     



     

    (electric) spark




    small luminous electric arc of short duration


    so from that it would seem that a spark is a short arc (which is effectively what Mike said earlier)


    * it turns out that the primary definition for "arc" is actually within IEC 62606 as this is referenced in the IEV entry.


Reply
  • I don't think "arc" or "spark" are defined in Part 2 definitions of BS7671 (given the time I am cheating and looking at an online pdf copy of the DPC for convenience rather than my official copy which isn't next to me right now).


    It is possible that IEC 62606 (standard for AFDD) has a specific definition for these terms*, if not then for an IEC based standard the definitions in the International Electrotechnical Vocabulary usually apply.

    This can be searched free online here: http://www.electropedia.org/


    Searching for "arc" includes the following result:

    arc
    arcing




    luminous discharge of electricity across an insulating medium, usually accompanied by the partial volatilization of the electrodes

    Note 1 to entry: A complete sinusoidal current half-cycle is not considered to be an arcing half-cycle.






     

    [SOURCE: IEC 62606:2013, 3.1]





    and searching for "spark" includes the following:

     




     



     

    (electric) spark




    small luminous electric arc of short duration


    so from that it would seem that a spark is a short arc (which is effectively what Mike said earlier)


    * it turns out that the primary definition for "arc" is actually within IEC 62606 as this is referenced in the IEV entry.


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