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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 --
: Hi,
: I just found your 'high voltage arcs & sparks' video download section.
: This is utterly incredible and I never thought I would see something like
: this on video. I was lucky enough to experience a 500kV disconnect 'hot'
: open on one phase to an unloaded transformer, in Virginia. This was not a
: rotary switch, but a horizontal-to vertical knife-blade type, simular to
: those on your '345kV' video, but this one has large metal arc 'globes' on
: the end of the blade and on the switch cradle. The resulting arc was much
: like the one you have here on video, but was ungodly loud to experience in
: person. A faulty rotary sf6 puffer switch was to blame, all have been
: replaced. These were the 'old-style' types with the giant beer-keg looking
: barrel atop the long bushing. These are rapidly dissapearing now with the
: event of the new smaller horizontal high pressure bottles. BTW, I notice on
: the main interuptor stacks in a 765kV station 100 miles to my southwest,
: these are 6 in series per phase. IMAGINE watching a 765kV arc!
: I was wondering on the 'second largest jacobs ladder' voltage. Is that
: meant to be 34.5kV? The insulator stack is way too short for 345kV.
: Please feature more of these type videos if you can find them. Also I am
: looking for another utility-made video on a helicopter disaster. I'm told
: it was shown on TV a few years back: it shows the little coptor w/platform
: and lineman in his suit approaching and coupling to a phase of (what was
: said to be 800kV). Everything is OK until the copter gets to close and the
: blades get close to the top mounted ground wires. The full load arc (only
: for a split second because sf6 interuptors upstream instantly killed the
: power) kills the copters pilot, but the poor lineman on the platform was
: the worst, the voltage went directly through him, and I'm told he actually
: exploded into pieces (I assume the amperage caused his body fluids to flash
: to steam) I have never seen this video, but have heard others talking about
: it. Do you know of it?
: And your substation explosion video is amazing. That 'low voltage' side arc
: must have been anywhere from 19.9kV up to 33 or more kV. It is a violent
: & nasty sounding arc, and all the black smoke coming up before the
: transformer let go, must have been the arc working on a circuit breaker or
: small transformer, or something with oil. As I am NOT a lineman, but only a
: 'fan' of ehv/uhv electricity, tell me about the 'expulsion fuse' that
: finally cut off the high-voltage. I would like very much to know how it
: works. I note that it only goes once the transformer's oil plume ignites,
: as fire is a conductor, and it looks like the fire actually started away
: from the arcing fault, nearer to the hV side of the station. Wow! Thanks,
: for any help you can give me here, and KEEP UP the good work!
: Fred
:
:
Hi Fred,
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