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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical 3-phase bleedover (was Re: Summary: Bay Area Power (2000-06-14))
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 2000-06-16-15:40:11 John Hall: > When you lose a part of a multi-phase circuit, you usually get > bleed through enduser devices that are still getting power through > the other phases. Your story is a lot flashier than mine, but I had a really memorable experience with 3-phase bleedover myself, once upon a time. I was working at a research lab in the Duke Medical Center, in a small building they called the Old Laundry Building, because it was. It had a really ancient and heavy-duty building power distribution panel; it had several 3-phase circuits running various big items; and it had of course loads of regular power circuits. Including our machine room. Well, the building power panel breaker for the leg that carried our machine room died. Actually I think it might have been a gigantic fuse that blew, it's been so long I don't remember. Anyway, our machine room was suddenly being powered by bleedthrough. Turns out those 3-phase-powered appliances had a pretty darned significant impedance, so our voltage available was suddenly remarkably sensitive to how much load we applied to it. Unload the circuits and the available voltage rose right up to about nominal, comfortably over 110VAC or so; load everything on and the voltage dropped down to something way way too low, like 40-50VAC or some such, again the details are lost to me, I'm sorry. Well, much of our machine room load was things like big SMD drives - --- Fujitsu Eagles, Hitachi DK-815s, and the like. Weighed a ton, drank power, and had sufficiently smart power supplies to take themselves offline and spin down when the power dropped too far. At which point the available power climbed up again, and they came on again. They were cycling up and down every minute or so until we managed to shut everything off. I think we only lost a couple of power supplies and one HDA, if I recall correctly. Gear sure was tougher then. Today I'd expect that kind of silly-buggers games to let the magic smoke out of every box in a machine room, with the possible rare exception of something indestructable like a 2511, too mean to die. And of course laptops, which ties in nicely to another thread I've committed hereabouts:-). - -Bennett -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.0 (GNU/Linux) Comment: For info see http://www.gnupg.org iD8DBQE5SpR8L6KAps40sTYRAjx2AJ9cFyczUkWqnDKbd0Mv6H52TMg4NgCaAr9O IEhUZyKjwQshKGd2QnDfw+c= =KRwh -----END PGP SIGNATURE-----
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