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

whjohnson
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!
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    Well, I'd say the standards probably need to change, and the hubris around how great the  devices we currently have may be in a real setting needs to subside, as demonstrably they are not, until we can show something that is actually useful, reliable, and cost effective.  And as part of that rock solid pass/ fail waveforms and test methods and test gear need to be available.  Otherwise it risks becoming as laughable as the little bell pulls the Victorians put on graves so the dead could ring them and attract attention if they woke up. Or perhaps if significant money is involved, then eventually we risk a mis-selling scandal more like PPI (although hopefully not as bad as the fantastic but cautionary tale of the non-working bomb detectors.) My point is that nice presentation, endorsement by apparent authorities and a slick advertising campaign are no substitute for a useful product.


    It might just be that detecting an arc from the current waveform of an unknown and rather arbitrary load, really is a very difficult problem, and there are better ways to invest against failures. Personally  I have been involved in the design of systems fitted  with UV detectors and EMP receiver antennas for detecting early breakdowns and potentially expensive arc / flash-over  failures, and the reason this was done, and we rapidly ruled out the option of  some DSP (Digital Signal Processing) on the current waveform was because this was not adequate, given the great variety of fail modes, and the absence of a catalogue of good and bad waveforms.

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    Well, I'd say the standards probably need to change, and the hubris around how great the  devices we currently have may be in a real setting needs to subside, as demonstrably they are not, until we can show something that is actually useful, reliable, and cost effective.  And as part of that rock solid pass/ fail waveforms and test methods and test gear need to be available.  Otherwise it risks becoming as laughable as the little bell pulls the Victorians put on graves so the dead could ring them and attract attention if they woke up. Or perhaps if significant money is involved, then eventually we risk a mis-selling scandal more like PPI (although hopefully not as bad as the fantastic but cautionary tale of the non-working bomb detectors.) My point is that nice presentation, endorsement by apparent authorities and a slick advertising campaign are no substitute for a useful product.


    It might just be that detecting an arc from the current waveform of an unknown and rather arbitrary load, really is a very difficult problem, and there are better ways to invest against failures. Personally  I have been involved in the design of systems fitted  with UV detectors and EMP receiver antennas for detecting early breakdowns and potentially expensive arc / flash-over  failures, and the reason this was done, and we rapidly ruled out the option of  some DSP (Digital Signal Processing) on the current waveform was because this was not adequate, given the great variety of fail modes, and the absence of a catalogue of good and bad waveforms.

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