Spectacular grounding problem.
Spectacular grounding problem.
(OP)
When was the last time you drove down the highway without seeing a commercial truck hauling goods?
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Spectacular grounding problem.
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RE: Spectacular grounding problem.
I wonder if our line fuses will do the same? Cable running outside house - very close to wooden wall...
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Spectacular grounding problem.
RE: Spectacular grounding problem.
Also the German transformer burning over the horizon was very eerie I couldn't help but think of War of the Worlds - it even had strange birdish sounds after it stopped.
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Spectacular grounding problem.
http://www.youtube.com/watch?v=NfSYQRorDgM&NR
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Spectacular grounding problem.
RE: Spectacular grounding problem.
Don
RE: Spectacular grounding problem.
When I first saw it in another website, it was labeled as a "grounding" problem and it was so long that I was still actually watching it when I posted the link, so by the time I figured out what was really happening I had already posted it. I suppose it still was a "grounding" issue in that one and eventually all of the phases were going to ground!
At first I thought the PoCo worker was extremely nonchalant about this, but I suppose he has seen it a lot more than the rest of us do and understood what was happening. I'll give him the benefit of the doubt that he was just being careful. Knee-jerk reactions to dangerous situations are often worse than just watching and waiting.
RE: Spectacular grounding problem.
Normal fusing is 250% of full load current. I have seen wye/delta banks fused at 1000% and more. Although available short circuit current may be in the range of 2000% to 4000%, in the real world, primary voltage drops and secondary impedances can easily limit the short circuit current to a value that the 1000% fuse will support for some time. It appeared from the arcs that a primary recloser somewhere upstream had disconnected and was reclosing avery several seconds. That would give the fuse some cool-down time and allow it to hold in longer.
Another factor, if the primary neutral is floating, when one fuse blows the other two transformers go in single phase series line to line. They now have an average of 87% of rated voltage. This will reduce the available short circuit current and allow the fuses to hold in longer.
short story. The fuses should be 250% and the short circuit current should be 2000% to 4000%, more than enough to blow the fuses.
Out on the pole (in the real world), the fuses may be rated higher and the short circuit current may be less so that the fuse don't clear.
respectfully