What happens to half a million volts when you unplug it

[ddamoore]

I read this in a newsletter from another group that I subscribe to.

Kinda cool to see the power unleashed.

http://www.arcfault.org/video.htm

[gmack5]

That was AWSOME, to say the least!
Like the guy in the video said "WOW"!

[ddamoore]

Found the video in a larger format

http://video.google.com/videoplay?do...104671&q=500kv

[lcm1947]

Man! WOW! is right. That was awesome. Thanks for the movie.

[Stick]

But........that's not a NORMAL arc. Many of you know I'm a power station operator by trade. Yes, High voltage AC switches do arc when opened or closed, but not quite like that. That's only one phase of the 3 that's arcing. There's a fault somewhere, or they're testing something. Still pretty impressive though. Normal would be all 3 phases, and straight across the disconnect arms until they're nearly opened. It's scary the first time you see it, especially when you're hand cranking the disconnect switch. Now High Voltage DC, that's another story. DC arcs don't extinguish, they'll keep going until the disconnect burns itself up. I witnessed one that was over 40 feet long, and burned for over an hour before they could get the entire station shut down to clear it. It was at night, and lit up the sky like daylight. You could see it 40 miles away.

[gsmittle]

Cool!

But........that's not a NORMAL arc. Many of you know I'm a power station operator by trade. Yes, High voltage AC switches do arc when opened or closed, but not quite like that. That's only one phase of the 3 that's arcing. There's a fault somewhere, or they're testing something. Still pretty impressive though. Normal would be all 3 phases, and straight across the disconnect arms until they're nearly opened. It's scary the first time you see it, especially when you're hand cranking the disconnect switch. Now High Voltage DC, that's another story. DC arcs don't extinguish, they'll keep going until the disconnect burns itself up. I witnessed one that was over 40 feet long, and burned for over an hour before they could get the entire station shut down to clear it. It was at night, and lit up the sky like daylight. You could see it 40 miles away.

Now THAT (the DC arc) is cool. Way back in the day, we used to use two-pin slip connectors for stage lighting. Once a spark curled around my bare hand and burned the hair on the back of my hand.

g.

[hitekrednek]

Ain't that some %!@#

When I was in the Army, one of my main jobs was dealing with high voltage DC power supples. I've seen some pretty amazing arcs coming off of a -15,000 VDC transformer but that has got to be the most amazing arc that I have ever seen.

[Stick]

Oh yeah, I should have said that I work with up to 500kV AC and +/-500kV DC. The station I'm operating right now is at 230kV AC, but the transmission lines are 160 miles to the next substation. Even with breakers open at both ends, the disconnects draw about a 4 foot arc when opening or closing, just due to inductance, which is basically static electricity either induced by adjacent conductors, or by air movement over the conductors. The longer the line, the worse it is. Our HVDC lines are over 450 miles between stations. We wear rubber gloves that insulate to 30kV to protect us from this when switching. There are insulators on the disconnects, but all it takes is a trace of dirt and it can cause a flashover, or leakage through to the operating handwheel.

What's even scarier is the live line guys. They wear a metal mesh suit, and it has a pigtail that they actually clamp on to the line and energize themselves to work on it. Like a bird on a wire, they're fine unless they contact ground. They either work from an insulated bucket truck, or from a helicopter. They don't pay enough for that kind of work....those guys are bonkers!

[just4funsies]

YOW! My backside just took a big bite out of my chair!!

[jdschulteis]

[. . .]
What's even scarier is the live line guys. They wear a metal mesh suit, and it has a pigtail that they actually clamp on to the line and energize themselves to work on it. Like a bird on a wire, they're fine unless they contact ground. They either work from an insulated bucket truck, or from a helicopter. They don't pay enough for that kind of work....those guys are bonkers!

I'd take it . . . if the only other job in the world was working on high steel!

--
Jerry

[Stick]

I did it once when I was an apprentice, just to see what it was like. Never again. They couldn't pay me enough, even though I understand it and know it's (relatively) safe, well, as safe as anything else is in my line of work. I'd MUCH rather work on "high steel"! When you go to attach the pigtail, IT draws an arc. The LAST thing you want to do is to clamp it onto the conductor, but you know you have to. You feel your whole body tingle for a few seconds. It doesn't hurt, but it feels really wierd, makes your hair stand on end, and mine is waist length! But you really have to be aware that you can't touch ground or you're history. The guys that do it all the time get a sort of "danger pay", but IMHO, it's not nearly worth it. Funny though, I can't EVER remember an injury among those guys. it's the guys working on the lower voltage distribution lines, like 66kV and lower, that get hurt. And a lot of the time it's because some wingnut has plugged a generator into his house without isolating the main breaker and it backfeeds through the lines. We've had quite few linemen injured that way. One I know now has no arms and only one leg. Yep, his own fault, they're supposed to check for voltage. He was overtired, trying to restore power after an ice storm and............

[sacherjj]

How does that country song go?

"It pays good money, but he sure can't spend it now..."