Re: [8023-POEP] Liaison letter from IEC TC65/SC65C/JWG10 - Power over Ethernet performance in industrial environments
Hi David and all,
It is not clear from the letter what portion of the PD or PSE or both were damaged?
Is it the PHY portion or the af/at interface and power circuitry?
What kind of transients the system was exposed too? Voltage, current ?
What is the PD/PSE Environment type? (A or B, it is relevant for immunity to transients etc.)
We need to compose a questionnaire to get this info prior to our response for guidelines.
From: owner-stds-802-3-poep@xxxxxxxx [mailto:owner-stds-802-3-poep@xxxxxxxx] On Behalf Of David Law
Sent: Tuesday, June 02, 2009 2:12 AM
Subject: Re: [8023-POEP] Liaison letter from IEC TC65/SC65C/JWG10 - Power over Ethernet performance in industrial environments
Thank you for your comments - I wanted to get some thoughts on this letter
prior to the meeting - and that seems to be working, which is good. As I
hope I made clear in my email, I was indicating my intent to delegate the
drafting of the response to this Task Force - but, as always, the actual
delegation will occur in the IEEE 802.3 Opening Plenary where the liaison
letter will be reviewed - and the actual decision could be different from
In respect to item #2, I do think this is an area that IEEE P802.3at has
some expertise in as  the question relates to the effects of transients
that are created on Power over Ethernet and  there has been work done
in IEEE P802.3at on the limits of the transient envelope. The draft, for
example, contains a PD specification related to limiting transients in
subclause 22.214.171.124 'Peak transient current' which specifies the maximum
transient current drawn by the PD in terms of mA/µs.
I do, however, take your point that we also need to involve twisted-pair
copper PHY experts. I believe the best place to find them is currently in
IEEE P802.3az. Based on that, I propose to take two actions:
1. When IEEE P802.3at considers this letter they make sure they coordinate
with IEEE P802.3az
2. I will send an email out to the IEEE P802.3az reflector to make sure
those interested can also participate.
In respect to the outcome reported at the IEEE closing plenary, I'm more
than happy if more time to work on this is what needed, and I agree that,
based on my reading of the letter, that may well be the case.
owner-stds-802-3-poep@xxxxxxxx wrote on 01/06/2009 19:26:20:
> After examining the letter, I would assert that the P802.3at Task Force
> does not have the expertise to address all of the issues raised in the
> letter. In particular, question #2 lies fully outside the expertise of
> the Task Force and should be brought before the Working Group on Monday.
> I would guess that Q2 might more appropriately be assigned to either
> maintenance or to the copper sub-task force of 802.3ba for a response.
> With respect to both questions, my guess is something more than just an
> anecdotal response should be considered. As such, it might be more
> appropriate to carry over the action item of a full response so that our
> members can gather up more information or (perhaps) solicit more
> specific failure information.
> Best regards,
> Geoff Thompson
> On 6/1/09 4:09 AM, David Law wrote:
> > All,
> > The IEEE 802.3 Working Group has received a liaison letter from IEC
> > TC65/SC65C/JWG10, Industrial process measurement, control and
> > automation/Industrial networks with respect to Power over Ethernet
> > performance in industrial environments.
> > I just wanted to inform you that I intend to delegate the generation
> > draft response to the IEEE P802.3at DTE Power Enhancements Task Force
> > during the plenary week in July. The draft response will be consider
> > then voted upon at the closing IEEE 802.3 Working Group plenary as
> > the IEEE P802.3at closing report. You therefore may wish to review the
> > letter prior to the meeting, the letter can be accessed at the URL [
> > ].
> > Best regards,
> > David Law
> > IEEE 802.3 Working Group Chair