[60820] in North American Network Operators' Group
RE: East Coast outage?
daemon@ATHENA.MIT.EDU (McBurnett, Jim)
Sun Aug 17 09:09:49 2003
Date: Sun, 17 Aug 2003 09:09:09 -0400
From: "McBurnett, Jim" <jmcburnett@msmgmt.com>
To: <hackerwacker@tarpit.cybermesa.com>,
"Michael Painter" <tvhawaii@shaka.com>
Cc: "Chris Adams" <cmadams@hiwaay.net>, <nanog@merit.edu>
Errors-To: owner-nanog-outgoing@merit.edu
--Huh ? Where in the physics of ohms law is Hz a factor ? Having lived =
off
--the grid, where systems are often at max 48v, yes the wires have to be
--several 0's of gage to carry the lagre amperages. Much the same in A/B =
DC legs in
--a colo. Up the volts and the amps go down to produce the same power =
(watts
--or work).
HMM, it's been a LONG time but I remember high amp, low voltage
The formula makes it a swap out. Raise the voltage drop the current, or =
lower the
voltage and raise the current if the resistance stays constant.
--I am a little rusty on this one, but I seem to remember that AC =
travels
--only on the outside skin of the wire but DC uses all the wire.
This is called the skin effect, and from my RF days we did not consider =
it
to be an issue until you get to close the KHz range. In high voltage
transmission lines it may get a little higher than 60 Hz, but I don't =
think by much.
I have many UPS that track HZ and I have seen it coming in from 59.8 to =
60.2.
The skin effect was a really big deal in the L band systems where I used =
to work.
1.2 GHz to 1.6 GHz. And in the S Band we had to use pressurized =
dehumidified=20
transmission Waveguide due to freq and power levels (2 Megawatts).
We did AC/DC conversion and worked with 400 Hz power for those systems, =
and we were
not concerned with skin effect at all. But we were concerned with RF =
induction into
the power systems supply lines that could dirty up the power input and=20
create problems for the ac/dc conversion for the discrete electronics.
anyway-it's been awhile...
J
