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No, I'm not saying that 175ma
will necessarily be OK. Our existing (non-802.3af compliant :} )
system draws up to about 250ma per MDI, so nominally 125ma per trace assuming
equal resistance w/o runaway, so we tested various patch panels with a current
limited lab supply and a simulated load. First vendor we tried as it turns
out failed - consistently blew the traces. On examination, the traces are
very very thin - I can't really tell you exactly what the copper weight of the
failed vendor was (yes, it's copper on what appears to be ordinary FR4), but by
inspection they're quite thin, corresponding to a surface layer signal trace on
a normal PCB.
We found two patch panel vendors (OK I can
name them - AMP and Lucent) who use fairly thick traces (tested them at 500ma
per trace with no problem) so we just use those two vendors, i.e. we didn't do a
statistical survey. I will say that the vendor who failed is considered a
fully reputable supplier in the industry.
Hope this helps,
SC
----- Original Message -----
Sent: Friday, May 04, 2001 11:24 AM
Subject: RE: Potential heating problem
with standard patch Cat5 panels
Scott,
are you saying that we will still be OK since we will be
actually using 175ma per trace,
which is 350ma total through our loop?
Are these traces copper or something
else?
-----Original Message-----
From: Scott
J. Carter [SMTP:scott_j_carter@xxxxxxxxx]
Sent: Friday, May 04,
2001 10:42 AM
To: Brooks, Rick [SC5:321:EXCH]; Jack Andresen;
stds-802-3-pwrviamdi
Subject: Re: Potential heating problem with standard patch Cat5
panels
We have seen Cat5E patch panels (from a vendor
who shall remain nameless) blow traces at about 250ma. Some vendors
use very thin traces indeed.
----- Original Message -----
From: Rick Brooks <mailto:ribrooks@xxxxxxxxxxxxxxxxxx>
To: Jack Andresen
<mailto:jandresen@xxxxxxxxxx> ; stds-802-3-pwrviamdi@xxxxxxxx <mailto:stds-802-3-pwrviamdi@xxxxxxxx>
Sent: Friday, May 04, 2001 6:58 AM
Subject: RE: Potential heating
problem with standard patch Cat5 panels
From my personal experience, a 12
degree C rise is trivial and would not cause any
PC board
discoloration, unless the PC board was operated above 100 degree
C.
Or the PC board material is faulty. I wonder if it is
FR4.
If the patch panels are being
damaged, there must be a whole lot more current involved than
350ma,
or the traces are very thin, or it has a different
cause.
- Rick
-----Original Message-----
From: Jack Andresen [SMTP:jandresen@xxxxxxxxxx]
Sent: Thursday, May 03, 2001 2:21 PM
To:
stds-802-3-pwrviamdi@xxxxxxxx
Subject: Potential heating problem with
standard patch Cat5 panels
A customer mentioned panels burning up
when one of his customers senr
power down the network.. I did some canculations and
found a potential
problem.
Jack Andresen << File: DTE power.doc
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