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Too Quiet1
Posted by Fred Berry on 9/20/2006, 6:51 am I was also excited when you finally heard from a Florida utility man on the actual reason/cause for the low-side arc. You were right, it was a capacitor bank. I still wonder what the low-side voltage was. My guess is 19.9kV, maybe higher, but for certain, not lower. That arc was too strong for anything lower. The linkbelt crane is still one of the most awesome displays of the power lurking in those overhead lines. THAT is a full-load arc. Note that in one photo the arc is on the left side of the crane, then on the right side. I thought it might have been arcing off the stabilizers on each side on the rear, but the metal wheel on each tire is closer to ground. Still don't know, but seeing the concrete being broken up by that amperage is scary. At 'only' 46,000 volts, that is one unGodly imppresive arc. This spring/summer I was treated to some glorious nite-time light shows during the spring storms that occur here every year. I live in a high rise, and enjoy sitting on my balcony to watch the CG's and 'cloud-crawlers'. As I can look over towards Annadale (VA.) I always see when a CG hits a power line. You see the bright white stroke, immediately after, the sky is filled with a blue-green glow of the arcing powerline it hit. Then part of the lights of the city are gone until the recloser re-engergizes the effected circuit. Often as not, the green glow re-appears, usually now mixed with dull orange as a bushing or other piece of equipment is burned, meaning a permantent fault. And lastly, I was treated to a sight I never saw before. On the intersection of Beuregard and Duke street, there is an intersection of utility lines, large 19.9kV jobs. There is also a very large flock of pigeons that hang around there. Well I happened to be waiting at the traffic light there when this huge flock came in for a landing across all three phases of the line and the wooden poles holding the line. Some unlucky bird (or group) connected the center phase of the line to ground (flapping wings?) The dragon appeared briefly, and over a dozen cooked and smouldering pigeons fell to the ground! I still cannot understand why these birds are able to land on an energized line. Even medium volteges like 4 to 7kV will make corona discharge-to-air which would mildly shock a large bird. 19.9, and even 33.3kV lines around here often harbor perching birds. Why? I DO note that larger lines are never touched by birds at all. Anything new in videos?
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Re: Too Quiet1
Posted by Bert Hickman on 9/21/2006, 11:12 pm, in reply to "Too Quiet1" Thanks for the kind words! We've got other videos. We'll add them when we get a chance (and more bandwidth). : Looking at that amazing photo of the close positive lightning strike...the I agree... but it's still quite an awesome shot, isn't it... :^) I suspect you're correct. Another lineman indicated that the substation had a primary voltage of 138 kV and a secondary side of 21 kV. I've updated the page to reflect this information. (I hope it's correct..) I also agree. A couple of folks have suggested that the mist was part of a water-based fire suppression system, but I recently found out that this substation did not use active fire suppression... Yeah... I wish there was some video footage of that even though... :^) : : And lastly, I was treated to a sight I never saw before. On the Wow! I've seen squirrels explode when getting across transformer bushings. And larger birds are a big problem in the western states with their large pole-top nests and wingspans that can create phase-to-phase crosses. : Birds apparently do detect the E-field long before actually getting zapped with corona on higher voltage lines. I've seen birds shy away from 235 kV lines from distances of 6 feet or more. However, perhaps smaller birds don't develop sufficient capacitive charging current when approaching lower voltage lines. Or maybe they're just stoic... :^) I've got a few more videos that I may eventually add - however, I increase the bandwidth on the site before doing so. : Take care, Best wishes, Bert
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