Electric Arc of Death?

January 16, 2004 5:12 AM

Maybe you've seen the Electric Arc of Death video.OK, so maybe it's just capable of death if you get too close. But, if you work in the power industry like I do, I was amazed to see this rather impressive video of a switchyard problem. Electric arcs involving switchgear for transmission lines are nothing new, and this link provides an excellent analysis of why this arc is occuring. Make sure you turn the volume up for an extra charge of excitement.
posted by insulglass (22 comments total)

Wow! That is cool. It's also one of the reasons I say (even though it's not true) that I got into IC design instead of power. I started working with 2.5 volts and it's been dropping every 6 months.

The corrected URL for the video

What's the URL to the explanation insulglass?
posted by substrate at 5:19 AM on January 16, 2004

Ahh, I think this would be it.
posted by substrate at 5:19 AM on January 16, 2004

Whoops, sorry, my this was already linked by you.
posted by substrate at 5:21 AM on January 16, 2004

Well, I've been reading MetaFilter for years and have participated in some lively discussions. However, this is my first post and sure enough, managed to bung the video link up. Oh well.

BTW... there is a huge arc potential to ground anytime you are near such high voltages and there is a large exclusion zone for personnel who are grounded. Take my word that you wouldn't want to walk within a few feet of that equipement, there's a reason that it is so high in the air.

I have been out in our 500KV switchyard on occasion and the air is literally charged with static electricity.
posted by insulglass at 5:51 AM on January 16, 2004

This is insanely cool. However, I have no idea what's going on. I barely remember the whole "[amps|volts] is like water pressure" schtick from a physics class I once took. Could someone explain it in easy terms?
posted by bonaldi at 6:14 AM on January 16, 2004

So we're sure this is real?

I can do this in about 10 minutes in After Effects. Given some more time, I could arc electricity from Goatse to the queen mum's nose.

Just wondering...
posted by jpburns at 6:19 AM on January 16, 2004

From the audio I'm convinced it's real. When the ionized air finally stops conducting the arc, if you listen carefully you can hear the echo the spark gave travel across the valley floor.

Tesla would be proud. From the link to the explanation substrate gave, the expert estimates the arc grew to about 3 stories before dissipating.
posted by Civil_Disobedient at 6:39 AM on January 16, 2004

Excellent! Thanks, insulglass. You can hear the beginning of one guy's "Whoaa!" right at the end of the clip.
posted by carter at 7:19 AM on January 16, 2004

Wow! That's just amazing to see. Thanks!
posted by riffola at 7:40 AM on January 16, 2004

jpburns, I will treat you to a couple of pints of Guinness any time you're in Birmingham if you will spend 10 minutes making a video of an arc from goatse to the Queen Mother's Nose, then email me the URL. (4 pints if you can do it via Tubgirl and Mother Theresa).
posted by Pericles at 8:02 AM on January 16, 2004

what bonaldi said -- can anyone do a quick "electricity for non-scientists" summary and explain in layman's terms what's happening here?
posted by sodalinda at 8:58 AM on January 16, 2004

(4 pints if you can do it via Tubgirl and Mother Theresa).


BUWAHAHAHAHAHAHA I will also contribute !!
posted by a3matrix at 9:11 AM on January 16, 2004

I can do this in about 10 minutes in After Effects. Given some more time, I could arc electricity from Goatse to the queen mum's nose.

Can you put in the guys on the ground and their reactions as well? All four of them are looking at the event. One of the guys on the lower right is crouching behind his truck (he is the one that jumps up and shouts "Woo!" right after the event). And two of them (one on the lower right and one on the lower left) are backing up while the event occurs.
posted by moonbiter at 9:24 AM on January 16, 2004

Current (measured in amps) is sort of like the amount of water flowing out of a hose. Voltage (measured in ... volts) can be compared to the pressure of the water.

Just as it takes a high pressure water stream to get a stream of water to shoot 50 feet, it takes a high voltage difference for an arc of appreciable size to form.
posted by lalas at 9:54 AM on January 16, 2004

Put simply:

If you look closely at the beginning of the video (first few frames), you can see 3 sets of switches opening. Each switch is two horizontal bars that are swinging away from each other, one with a ball on the end, the other with a receptacle for that ball. The massive arc occurs across one of these switches as it opens.

These switches had a whole lot of current flowing through them. lalas has the right analogy, it's like a lot of water flowing very fast through a pipe. Over at the right of each switch is a massive inductor (behind the truck). Inductors have the property that the current flowing through one cannot change instantaneously (because of ugly magnetic effects with weird Greek letters and such).

When the switches open, there is no longer a path for the inductors' current to flow, but it can't stop immediately. Instead, it continues flowing, building up a massive voltage. There are a lot of electrons sort of jammed up against the end of the now-open switch, and they would really much rather be on the other side. Think water pressure, what happens when you quickly shut off a high-flow-rate pipe? Pressure builds up and there can be a physical jolt of some sort in the pipe.

In a pipe, there is nowhere for the water to go, unless the pipe bursts. With electricity, it can go through nearly anything if it has enough motivation (voltage). So this massive voltage builds up until it rips apart the molecules in the air and creates a path for the current to flow.

In short, it's like instantaneously shutting a valve in a very high-flow pipe, then having the sudden buildup of water pressure break through the valve.

It happened because one of the two horizontal gray things to the right of the switch closest to the camera failed. Those are supposed to split the voltage over themselves, so each takes half and the switch itself gets none while it's opening (I think).
posted by whatnotever at 10:35 AM on January 16, 2004

Saw this on memepool a couple of days ago and it sounded to me like the "analysis" was more of a hypothesis. The guy who wrote the explanation was not present, nor does he work at the same facility. Sounds like he's making very educated guesses and knows some of the equipment by sight, though. I thought that should be underscored.
posted by scarabic at 10:45 AM on January 16, 2004

Be careful that you don't become part of my PATH TO GROUND!
posted by Hildago at 10:53 AM on January 16, 2004

scarabic: True. But the explanation of why/how arcing occurs stands regardless of the specific equipment. All switches can arc a little. This was just a big switch, and the stuff that usually keeps it from arcing didn't, for whatever reason.
posted by whatnotever at 10:55 AM on January 16, 2004

You think they knew this arc would happen or a potential existed, why else the camera? Thanks insuglass, great find.
posted by thomcatspike at 11:04 AM on January 16, 2004

Scarabic, true about the analysis. While I occasionally work on some switchyard components, the equipemnt involved and the current flow characteristics and properties are a science unto itself.

I claim no special knowledge or years of experience, but the writer of this article seems to have the right background to make a plausible analysis. Other people I do work with have very similar theories (if not the same one), and I trust their judgement. My power plant is currently undergoing a MAJOR switchyard renovation and there are plenty of knowledgeable and experienced people here on site.

I have been told by a friend of a friend (for what it's worth) that the switches - one for each phase - are supposed to work at the same time, but in this case they had problems with one "sticking" a bit. That's why there was film taken, SoCal Edison had similar problems before and were documenting it every time the switches opened.

The right combination of voltage and equipment, the lagging switch, and environmental conditions such as temperature and humidity all came together just right for this arc. Arcs are common in switching activities, just not of this magnitude and duration.
posted by insulglass at 11:06 AM on January 16, 2004

Another interesting factoid: while air requires a lot of current to become conductive, fire is an excellent conductor of electricity. Be careful if you ever mix the two.
posted by Civil_Disobedient at 12:51 PM on January 16, 2004

Civil_Disobedient: fire is an excellent conductor of electricity

i had no idea, but the mad scientist in me now really wants to build a flamethrower/ taser. Just think of it, it's not bad enough that you are lighting someone on fire, you are also zapping them with electricity.

How deliciously evil.
posted by quin at 4:17 PM on January 16, 2004