As came up in a conversation…
To learn about the impact of an arc fault in a full range of electrical equipment with both copper and aluminum conductors, the researchers took their commercial high-speed and infrared cameras to KEMA Laboratories in Chalfont, Pennsylvania, an independent testing lab with unique electrical equipment capable of generating high energy arc fault conditions.
Optical engineer Anthony Tanbakuchi and lead technologist Byron Demosthenous put the cameras behind a cinder-block wall to get them close to the arc fault while also protecting them from the heat. They pointed the cameras toward high-grade mirrors and recorded the reflection of the explosion at more than 1,000 frames per second.
The team recorded an arc fault that lasted four seconds with 26,000 amps of current. Reviewing the high-speed footage, the researchers saw how the steel panel enclosing the switchgear vaporized within half a second of the arc initiation.
“In seconds, a perfectly good cabinet was destroyed,” LaFleur said.
Of particular interest:
High speed of the cabinet vaporizing: https://share-ng.sandia.gov/news/resources/news_releases/images/2019_video/high%20speed%20vaporizing.mp4
High speed thermal imaging: https://share-ng.sandia.gov/news/resources/news_releases/images/2019_video/high%20speed%20thermal.mp4
And high speed HDR of the cabinet vaporizing: https://share-ng.sandia.gov/news/resources/news_releases/images/2019_video/high%20speed%20HDR.mp4
Takeaway? Don’t mess with arc faults.
Man, the arcing/flames coming out of the cabinet spews out so fast it hardly looks like high speed video. Just the smoke looks slow.
Also the HDR video looks more dramatic than any CGI explosion I’ve ever seen.
According to a coworker, people have been “vaporized” by arc faults.
Didn’t realize it was ‘slow motion’ until I looked at the counter.
Speaking of arc faults… since Syonyk had some unwanted guests in a battery box, I was reminded of something a few years back: Wasp-induced arc faults.
Wasps, being particularly annoying (and potentially deadly to some like myself) have the most irritating ability to infiltrate any not-so-usually-opened-up space for their nesting pleasure. I’ve seen them in camera housings, the reciever of my RV’s tow hitch, telecom boxes on polls, and so many other places… but usually you have to get rid of them with some wasp spray before you can resume whatever you’re doing.
Not the case a few years back for one particular nest: The one inside a high-voltage box.
Apparently some wasps had, as they are wont to do, made a nest inside one of those boxes you see in and around industrial buildings that have “DANGER! HIGH VOLTAGE!” plastered all over them. Evidently, the wasp nest just kept getting larger and larger, until one day, an unlucky wasp must have managed to cause a momentary short either to ground or across two of the phases, and bang! pop! Just like that, some equipment shut off and everyone came running to see what was going on. Upon opening the box, charred remains of wasps and their nest were found. Not a single remotely-alive one though!
I can only speculate as to how exactly these wasps managed to get this /just right/ to arc this AC supply across their bodies and/or nest before stuff tripped, but I guess it likely didn’t take that long with 500 Amps or so at a few hundred volts to cook them way past well-done.
Usually, arc faults aren’t good news, but in this case, it seems like one did us a favor, and gave a sizable group of wasps what they had coming to them. XD
Maintenance sucked the debris out, blew it out with some compressed air, and reportedly was able to just reset everything and turn stuff back on.