Hi all,
Regarding the protection of PSE and PD
ports:
The current IEEE802.3/af is taking care of
these issues as follows:
Environment A: All system segments are
within the same building, Power source gnd is referenced to a single system
gnd.
-
1500Vac rms isolation between MDI to chassis GND
-
Port toport isolation is not required
Environment B: Parts of the system
segments are locating outside the building, system may be powered from
different power sources with different GND.
-
1500Vac rms isolation between MDI to chassis GND
-
1500Vac rms isolation from port to port
Protection measures (circuits) against
transient voltage, lightning etc are implementation specific and are out of
scope of the IEEE802.3af.
Yair
From: owner-stds-802-3-poep@xxxxxxxx
[mailto:owner-stds-802-3-poep@xxxxxxxx] On
Behalf Of Mukundan R
Sent: Monday, January 31, 2005
7:44 AM
To:
STDS-802-3-POEP@xxxxxxxxxxxxxxxxx
Subject: Re: [8023-POEP] Query of
Protection for PoE
Thanks Geoff Thomson,
Waiting for the group to give its thoughts and action points..
Regards
Mukundan
Geoff Thompson wrote:
Mukundan-
Now that your question has been refined to be within what I believe is the
scope of the group, I will turn it over to the group for consideration when we
come to that part of the project.
To date I have not heard anything said about raising any of the minimum
isolation requirements set forth in the current standard.
Best regards,
Geoff
At 03:20 PM 1/29/2005 +0530, Mukundan R wrote:
Hi Geoff Thomson,
Yes, EFM could be where this can lead to more problems. But in PoE, how are we
going to protect the PoE PSE and PD ICs' from failure? Will the 1500V isolation
and the fuse present enough to handle this? the query i have raised can
happen in indoor cabling also.
There will be people in this group who would have dealt with these issues
earlier itself. And when we are trying to provide comments for the cabling
addedum, i wanted to bring this dimension also..ie, for example do we think of
a protection mechanism in the cabling itself? But that will not make the
standard attractive.
Thanks and Regards
Mukundan
Geoff Thompson wrote:
Mukadan-
There was nothing wrong with your query. The scope has not yet been formally
set for PoEplus. I would say (only my opinion) that the predominant sentiment
is to confine the work to augmenting the power available via clause 33 (and
changes appropriate to support that).
I believe what you are asking for is power for use in copper outside cabling. I
believe that would be a separate project directed at the copper PHYS specified
in IEEE Std 802.3ah, Ethernet in the First Mile.
I believe that it is unlikely that there will be a change in the 802.3 standard
that will include the use of 10BASE-T/100BASE-TX/1000BASE-T in outdoor
situations.
Again, just my opinion.
Best regards,
Geoff
At 09:57 AM 1/28/2005 +0530, Mukundan R wrote:
Geoff Thompson-
Thanks for the information provided.
Yes, i saw this clause in the standard and know its beyond the scope of the
IEEE Std.
But, the reason i raised this query is to try get a systems approach to the
PoE. Just by having a standard we cannot forward that, we need to use that
standard to design products that the customer might require and install at
totally different real world infrastructure.
And as the PoE is now trying to go for higher wattage, i wanted to check
whether we are considering in this angle also.
It would be grateful if the correct forum / any archive discussing this issue
earlier is pointed, so that i need not query at the wrong place.
Thanks and Regards
Mukundan
Geoff Thompson wrote:
Mukadan-
This is not considered to be within the application space.
9.7.2 Environment B
requirements
The attachment of network segments, which cross
environment A boundaries, requires electrical isolation of 1500 V rms, 1 min
withstand, between each segment and all other attached segments and also the
protective ground of the repeater unit.
If segments are of an electrically conductive medium,
it is recommended that this isolation be provided by the use of external MAUs
connected by AU Interfaces. If internal MAUs are used for attachment to
conductive media segments, then the segments shall be installed such that it is
not possible for an equipment user to touch the trunk cable screen or signal
conductor. A repeater of this variety requires professional installation.
The requirements for interconnected electrically
conducting LAN segments that are partially or fully external to a single
building environment may require additional protection against lightning strike
hazards. Such requirements are beyond the scope of this standard.
It is recommended that
the above situation be handled by the use of a nonelectrically conducting LAN
segment (see 9.9 or Clause 15).
See also 27.5.3.2
See also 41.4.3.2
Best regards,
Geoff Thompson
At 09:29 PM 1/27/2005 +0530, Mukundan R wrote:
Hi,
This is Mukundan from madras, India.
We are implementing PoE in our Metro Ethernet Switches.
Thanks for this mail on the telecom cabling standard for DC power requirements!
We are checking on what is the protection /safety procedure to be implemented
for PoE protection in the designs. ie, when we say PoE, the concept is to power
remote products / appliances and this cabling could be across buildings / intra
building.
IEEE 802.3af as such does not indicate on the GR / ITU-T standards like GR1089
/ K.21 / K.20 power crossing requirements. Indoor cabling has more issues with
power crossing than lightning whereas outdoor ethernet cabling is prone to
lightning.
The PoEplus is striving for nearly 40watts of power, which exaggrates the
requirement for a secure cabling infrastructure especially burn proof in case
of short circuiting - an extreme state of power crossing.
The Query: Whether the meeting proposed on the cabling structure can take in
this
dimension of query ?
or
Whether the interims session meeting will be the appropriate forum?
Thanks and Regards
Mukundan
Michael McCormack wrote:
I apologize for the
late notice; however, I am giving as much as I have received . . .
There will be a meeting this
evening to determine if a response is warranted from the 802.3 to the TIA
regarding their latest draft of " P-4425-AD6-D (TIA/EIA-568-B.1-6)
'Commercial Building Telecommunications Cabling Standard Part 1: General
Requirements. Addendum 6: Additional Cabling Requirements for DC Power'
" and if a response is warranted, then what the response should be.
This response needs to be drafted from the viewpoint of the existing 802.3
standard. The meeting will take place in the Windsor Room of the Hyatt
Hotel this evening at 6:00 PM Vancouver time.
All interested parties are invited
to attend; however, I would like to extend a special invitation to anyone who
has worked on the current specification (i.e. worked on 802.3af) and / or has
crafted previous responses to previous revisions of the TIA document to please
make every effort to attend this meeting.
Mike
P