Thanks for your answers! Now I know where the 'bang' comes from when a fuse blows. I have seen these go on 19.9 kV poles. These are the smaller vertical fuses that swing down when blown. And yes, when they go, the resulting explosion is terrifyingly loud. The small woven metal wire link is always clean (no burning)also the ends is frayed open like it was exploded outwards. And these are small fuses. I have seen real long fuses on some 230kV stations on the incoming hV side. I can just imagine the sound of one of these going...
Was there any followup on the substation arcing fault? What caused the arc and what was arcing? Looking at your video, the arc appears to be midway up the bus support structure.
I would love to see the video of the hV to lV crossover with houses arcing. That must be a mess! Also, your photos of the linkbelt crane becoming energized and exploding the concrete. I saw the aftermath of a simular incident, but a bit more ugly: I live just outside of Washington DC. A local family man was caught spying. Several TV stations sent their satellite trucks to his residence where they set up for video. One of them raised the extendable antenna tower on their van up into a 3-phase set of 19.9kV lines in front of the house. One of the TV men was sitting in the open side door of the van with his legs dangling. When the van became engergized, the mans legs arced to ground creating a three foot wide crater!! His legs and feet were vaporized and he was dead at the scene. Now just imagine the same scenario, but with 765kV and the several thousand (up to 8000 surge amps) amps and imagine what that arc would look like!
: --Previous Message--
: : Hi Fred,
: Thanks for the kind words. I have a number of friends and contacts in the
: utility industry, and from time to time they send me
: "interesting" pictures and video clips.
: You may be right about the 345 kV arc actualy coming from a lower voltage
: system. The utility industry contact who sent it to me indicated that the
: footage was captured in their system, and was being used in their training
: program. He also said that it came from a 345 kV switch... but the
: insulator strings do look a bit short for this.
: I hadn't heard about the helicopter incident before. It sure sounds quite
: gruesome! I'll have to look for it. There's also another video where a
: higher voltage circuit gets crossed onto a lower voltage distribution
: circuit, resulting in a batch of homes catching fire (with lots of arcing).
: Unfortunately, some of this footage is copyrighted as part of commercial
: safety/training programs, so I may not be able to show it on my site.
: An expulsion fuse uses a fusible link surrounded by insulating material
: inside a heavy fiberglass tube. The material surrounding the fusible link
: (usually borax) breaks down when the fuse blows from the heat of the
: resulting arc. This liberates a large volume of hot gases. These hot gases
: are explosively ejected from the tube, carrying away the metallic vapor
: from the fuse element. The evolved gases help cool the arc, and the high
: velocity blast extinguishes the arc at the next zero current crossing. BTW,
: when one of these devils blows, the dynamite-like bang is guaranteed to
: scare the living crap out of anyone within a 100 yard radius... :^)
: Best regards,
: -- Bert --
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