Major arcing!

[HFRH28]

http://www.wiseguysynth.com/larry/day.htm

The above link will take you to a page that contains a video of a ½ million volt switch failing to interrupt the arc when operating. (Interesting read also) MAJOR arcing! Just a reminder that we all need to keep our heads up anytime we're working around wires and electricity or even better, KILL THE POWER!


Direct link to video:
http://oldcrows.net/~oldcrow/Lugo_SWR.mpg

[Nail200]

Thanks

[Berks2Montco84]

Wow, I had no idea what the guy was talking about, but that was a cool video...

[DaSharkie]

Somebody want to put some water on that or what?

[HFRH28]

Hey sharkie, get the probie to go urinate on that electric fence!

[Dave1983]

Damn, I HATE electricity! Its the one thing we encounter that really scares the sh** out of me.

[ftfdverbenec770]

thats a great video. thanks for sharing.

[PattyV]

I agree, electricity give me the creeps. Its got so much uncertainty with it. Without fail i always assume it is alive until i have checked and double checked with the energy guys. I hate the uncertainty of it.

[CAPPYY]

COOOOOL! Thanks, I turned the sound up on my system and it made my hair stand up!

Arrive on scene, wires down, arching or not I order all units to stay at least one and a half poles away. Notify electric company, give pole numbers from a pole down the street, shut down the street, evac the area, people out the back of there houses if necessary, run caution tape, watch for overload fires that might break out in the area and keep an eye out for that kid who always comes riding his bike around the corner at full speed. Then sit, order up coffees and wait the electric company 30 minute response time (usually 1-2 hours).


God bless and pull the ceiling as you go.

[PattyV]

keep an eye out for that kid who always comes riding his bike around the corner at full speed.

Just slash his tyres and you wont find him coming around the corner anymore. Where i live it always seems to be a motor cyclist, especially on saturdays and sundays when they go for a ride out in the mountains.

[nmfire]

http://205.243.100.155/frames/longarc.htm

Has that video and several others. My personal favorite is the substation explosion.

[fireguy919]

Check out this video of a power sub station trying to put it's self out. What ever the supression system is just ****es it off.

http://www.big-boys.com/articles/transblow.html

[District821]

That transformer explosion looks to me more like what we call a boil over in the oilfield, than an extinguishing system.

[nmfire]

That's not an extinguishing system. There is a serious arc to ground on the low side of the substatation which is overheating this poor transformer. The oil inside was heated to the point of boiling. The vapor pressure blows off a relief valve which vents this flamable vapor cloud. The arc ignites the vapor cloud and ba-boom. The last big flash is the breaker finally tripping, day late and a dollar short might I add. There's more details in the link I provided abouts. I showed this to someone I know who manages a large transmission system and your could tell it was painful to watch something so expensive explode in your face.

[RLFD14]

nmfire is right, but I will clarify a few additional things.... but ignore this post if you want to avoid three times as much information than you are probably really interested in.

The bang is probably not the breaker, it is probably a fuse. Breakers make a machine-like clang (plenty loud to be sure), but when high voltage fuses go they generally make a classic explosion sound.

High voltage transmission and distribution systems are not protected with solid state equipment like your house, thus a high voltage breaker in and of itself will not generally self-operate because of a large amount of fault current passing through it. Breakers are operated through relay protection. A relay is a piece of equipment that can be programmed to detect faults in specific directions at specific distances. Depending on which relay(s) detect a fault, certain breakers are instructed by the relays to operate to isolate the problem.

Getting even further in depth:
A typical protection scheme involves something called "zones of protection". Three zones is the common application. Zone 1 watches for faults from the breaker down about 80% of the line. Zone 2 watches for faults from the breaker down about 120% of the line, over-reaching the other end. Zone 3 watches for faults behind the breaker (bus and transformer faults). Most relays are not capable of or programmed to watch for faults on the other side of any transformers, though. There are a myriad of systems to respond to faults in different ways depending on which relays see the problem and how far away the problem is. Some relays will "talk" with each other and compare notes before taking action (another topic entirely), but generally the necessary breakers will be open within 5 cycles or less (5/60ths of a second) from the time the fault occurred, which is awfully damned quick for the fault to happen, to be seen, for the computers to analyze it, the trip signals sent, and the mechanical breakers to operate.

In some cases, a substation may be located on a "tap" off a transmission line. There are breakers at either end of the line, but not necessarily one on the tap. The relays at either end can see faults on the line and tap up to the transformer, but can't see faults between the transformer and the low side breaker or bus. In these cases, a fuse is often placed on the high side of the tap to the transformer and it should pop for high fault current anywhere between itself and the other side of the transformer (areas invisible to the low side relays) without the whole transmission line coming out because of a problem on the tap. I suspect that this was the situation in the video. If I had to guess, the fuse that popped was the wrong rating (like replacing a 5 amp fuse in your car with a 30 amp fuse), therefore the fault current was sustained through the fuse while outside the detection range of the high-side breaker relays (which could not see the fault on the low side of the transformer), and the low side breaker relays (invisible to Zone 1 and Zone 2, Zone 3 may have detected it but had no programmed remedial action to take). Eventually, the fuse gave out, but it was too late, the multi-million dollar transformer was itself transformed: into slag.

Mostly this long windbag post of mine is just conjecture on what happened in this specific situation, but if a couple of people found it interesting then it was worth posting.

Stay safe!

[nmfire]

Alright, fuse

I love learning about transmission and distribution systems, you won't hear me complain. The guy I showed the video to had a similar explanation but it was like 2 years ago so I don't remember all the details like you just layed out (video is old). He immidiately had me put it on a CD for him so he could send it to all his co-workers.

[TCFire]

Thanks RLFD and NM...as usual, very informative discussion!

[tfpd109]

So we have the probie hit it with a 2 1/2", right?

[roundmtnvfd3]

nah, give em a super soaker

[HFRH28]

Na, Give him a water can!