Re: [8023-POEP] Query of Protection for PoE
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