Some of you may be able to activate the video by clicking on the pix to the left side of the screen at this site. I could not, but when I used this address, it came through fine: http://oldcrows.net/~oldcrow/Lugo_SWR.mpg
The website explained that the POCO had been having a lot of difficulty with this switch clearing the line, so they had set up this video test to pinpoint the problem. Look closely at the front left-hand horizontal insulator (actually a SF6 interrupter bottle) at the very start of the video. You'll see a flashover arc because it's companion on the right failed to open properly, allowing the flashover. That part of the arc goes out as the bottle contacts reclose.
The proper cyle for this switch is: open commanded-linkage starts to open-interrupter bottles open[internal contacts]-main contact begins to swing open-interrupter bottle contacts reclose-main contact finishes opening.
The main arc went out because the POCO had an upstream Oil Circuit Breaker open. (Another source reported that the OCB was also badly damaged by this incident.)
Luckily there was no wind at all or that arc could have easily gone phase-to-phase. My POCO friend explained that if that had happened, it was highly likely none of those workers in the video would have escaped unhurt.
Stupid should be painful.
Re: Mother Of All Sparks#59851 12/18/0502:22 AM12/18/0502:22 AM
My PoCo experience tells me that you should stay right out of the way of things like this. I'm suprised that there are no fences around a thing like this. Is it just my connection, or are those arms slow in moving?. At 500kV, they would need to be a lot quicker moving than that. All of our 66kV and 110kV sectionalisers use spring loading to pull them apart after you operate them with a handle from below.
Re: Mother Of All Sparks#59852 12/18/0503:28 PM12/18/0503:28 PM
My understanding of that type of switch is that the SF6 interrupters do the actual load make and break, they operate at a very high speed. The arms are to provide a visible break and substantial clearance to prevent arc restrike.
Since the one bottle failed in this situation it allowed the arc to form.
The arm travel on my highspeed connection with the video going normally takes about 3-5 seconds.
The reclosing sequence goes something like this: reclose commanded-bottles contacts open-arms close and seat-bottles reclose.
This was also at a very large power plant (not a substation as mentioned) so I'm willing to bet there is a fence around the whole switchyard.
Footnote: Anyone curious about these kinds of things should get the book I have, "Standard Handbook For Electrical Engineers" (Thirteenth edition) Authors Donald G. Fink/H. Wayne Beaty; Published by McGraw Hill. Might have a later edition out by now, mine is several years old.
It has a lot of information and comprehensive section on transformers including maintenance recommendations.
Stupid should be painful.
Re: Mother Of All Sparks#59853 12/22/0512:13 AM12/22/0512:13 AM
Wauuuuw, what a spark. The ABS switch seem to be rather slow in opening. The arcing appears to be across 1 of the phases. It looks to me that one of the load breaking OCB's or gas switches didn't break the load propery and one of the phases was still being switched by the ABS under an enormous amount of inductive type of load.
Great videoclip, amazing that a camera was handy to take the shots.
The product of rotation, excitation and flux produces electricty.