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Re: Potential heating problem with standard patch Cat5 panels



Title: RE: Potential heating problem with standard patch Cat5 panels
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 >>