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you have questions that many people have (including myself), and probably few if any have the answers they are willing to share.
These are my opinions is response to your questions:
a) the best model would be for a CAT-3, CAT-5, and CAT-6? fully coupled cable, 8 x 8 matrices of RLGC (this does not exist)
b) next best would be treating the 4 pair cable as 8 separately charged 50 ohm lossy coax cables
c) the next best would be to use a separately charged lumped cap (4000 to 6000 pf?) on each RJ-45 pin to ground
1.1) I think that this would work, but determining the TBD's is hard to do, since there is coupling in any real cable.
Also, when the RJ-45 is plugged in, the pins can mate in any order, so multiple modes can be stimulated:
differential mode (within a pair), pair to pair mode (from one pair to other pairs), and common mode.
2) cable discharge applies to any cable, in our case: CAT-3, CAT-5 (5E), CAT-6, etc...
The better the cable performance, often the worse the charge retention is, and the higher the voltages could be.
We can always find a test condition that blows things up, the hard part is finding a test condition that properly covers most
of the real world installations. No fair plugging into ethernet ports which are riding on say a Van de Graf generator.
From: Yair Darshan [SMTP:YairD@xxxxxxxxxxxxxx]
Sent: Saturday, September 16, 2000 3:01 PM
To: 'RDLove'; Dieter Knollman; stds-802-3-pwrviamdi@xxxxxxxx
Subject: RE: Static Discharge - An issue to be added to the technical issu es list
I am looking for more information regarding the issue of charges accumulated
As I remember Roger has pointed that he measured 750V due to this phenomena.
The information that I need is the following:
1. What will considered to be acceptable circuit model that we can use to
analyze worst case conditions?
1.1 Can we assume that the worst case situation is applying charged
capacitor of TBD nF with TBD voltage and connect it through TBD impedance
between the feeding port and between the feeding port and system
2. Is it applies only to cables from CAT 5E and up?
Chief R&D Engineer
> PowerDsine Ltd. - Powering Converged Networks
> 1 Hanagar St., P.O. Box 7220
> Neve Ne'eman Industrial Zone
> Hod Hasharon 45421, Israel
Tel: +972-9-775-5100, Cell: +972-54-893019
> E-mail: <mailto:yaird@xxxxxxxxxxxxxx>.
> -----Original Message-----
> From: RDLove [SMTP:rdlove@xxxxxxxxx]
> Sent: ו, ספטמבר 15, 2000 7:46 PM
> To: Dieter Knollman; stds-802-3-pwrviamdi@xxxxxxxx
> Subject: Re: Static Discharge - An issue to be added to the technical
> issues list
> Dieter, thank you for the input. I will record the following as the first
> additional technical issue to be added to our issues list:
> Decide if there is a need to specify a discharge path for the
> on the cable. If the answer is yes, decide if it should be part of the
> requirements or an informative annex. Then complete the work for
> incorporating the information in the draft.
> Best regards,
> Robert D. Love
> President, LAN Connect Consultants
> 7105 Leveret Circl
> Raleigh, NC 27615
> Phone: 919 848-6773
> Fax: 720 222-0900
> email: rdlove@xxxxxxxx
> ----- Original Message -----
> From: Dieter Knollman <djhk@xxxxxxxxxx>
> To: <stds-802-3-pwrviamdi@xxxxxxxx>
> Sent: Friday, September 15, 2000 12:53 PM
> Subject: Static Discharge
> > Hi,
> > My background is telephony. I'm totally new to 802.3, so please excuse
> > my ignorance.
> > One thing that appears strange is the lack of an intentional discharge
> > path for the potential on the cable.
> > The only means that I have found is breakdown of the common mode
> > termination capacitors.
> > Are these caps with 2 kV rating intended to be leaky?
> > On POTS line interfaces the Tip lead is typically biased around ground
> > and serves as a discharge path to earth ground for Analog Sets. Do the
> > IP Phones require a discharge path via the LAN?
> > Dieter Knollman
> > DMTS
> > Lucent
> > djhk@xxxxxxxxxx