Re: [8023-POEP] 802.3af Isolation 33.4.1
Hi all,
I remember that I was surprised too to see the deletion of the 2250Vdc
option from the IEEE802.3af very close to the date when we done with the
standard and as far as I remember I was told that it is due too new
version or update of the UL1950 and I also remember that it was done due
too one of the comments we had received? However it worth checking it
again.
I do believe that the 2250Vdc option is valid too since it is "low
frequency" as 1500Vac rms 50-60Hz and this is what practically is being
done when testing isolation according to en60950...
I'll check again what the EN60950 has to say and if it is OK we can ask
for update.
Yair
Darshan Yair
Chief 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: +972-54-4893019
Fax: +972-9-775-5111
E-mail: <mailto:yaird@xxxxxxxxxxxxxx>.
<http://www.powerdsine.com>
-----Original Message-----
From: owner-stds-802-3-poep@xxxxxxxx
[mailto:owner-stds-802-3-poep@xxxxxxxx] On Behalf Of Lappin, Bob
Sent: Thursday, April 21, 2005 6:10 PM
To: STDS-802-3-POEP@xxxxxxxxxxxxxxxxx
Subject: Re: [8023-POEP] 802.3af Isolation 33.4.1
David,
Thanks for your reply. I searched the comments document and found
several references to paragraph 33.4.1, but nothing regarding the
deletion of the 2250VDC testing option.
Who should I contact regarding the approved standard IEEE Std
802.3af-2003 DTE Power via MDI?
I respectfully ask the IEEE 802.3 Power over Ethernet plus Study Group
to consider adding the 2250VDC to the list of options for electrical
strength testing.
Regards,
Bob Lappin
-----Original Message-----
From: owner-stds-802-3-poep@xxxxxxxx
[mailto:owner-stds-802-3-poep@xxxxxxxx] On Behalf Of David Law
Sent: Thursday, April 21, 2005 3:57 AM
To: STDS-802-3-POEP@xxxxxxxxxxxxxxxxx
Subject: Re: [8023-POEP] 802.3af Isolation 33.4.1
Hi Bob,
While I cannot give you an official answer, as a personal observation I
would state that as far as I am aware there have been no changes to
subclause 33.4.1 since the approval of IEEE Std 802.3af-2003.
If you are interested in the background to the development of this
subclause you may want to review the IEEE P802.3af DTE Power via MDI
Task Force web archive [ http://www.ieee802.org/3/af/index.html]. As
another personal observations, I do seem to recall that there was a lot
of work on this subclause during the devolvement of draft D4.1 in
particular. I would therefore suggest looking at the comment and
responses database for D4.0 [
http://www.ieee802.org/3/af/comments/d4.0/P802_3af_D4_0_all_final.pdf ]
and searching the file for '33.4.1'.
And finally, before the Chair of this Study Group has to remind us all,
to quote the reflector welcome message 'The IEEE 802.3 Power over
Ethernet plus e-mail reflector is provided to the members of the IEEE
802.3 Power over Ethernet plus Study Group for the benefit of moving the
work of the Study Group forward.' I will therefore note that this
question relates not to the IEEE Power over Ethernet plus Study Group,
but instead to the approved standard IEEE Std 802.3af-2003 DTE Power via
MDI.
Best regards,
David Law
> From: Lappin, Bob <rlappin@xxxxxxxxxxxxxxxxxxx>
> Date: Apr 20, 2005 7:59 PM
> Subject: [8023-POEP] 802.3af Isolation 33.4.1
> To: STDS-802-3-POEP@xxxxxxxxxxxxxxxxx
>
> I would like to know the reasoning for the change to the Isolation
> requirements in paragraph 33.4.1.
> Previously, 2250VDC was an acceptable test option. That option is no
> longer shown in the 802.3af specification.
> The MDI interface will typically have a capacitive path to frame
> ground to attenuate common mode noise. This capacitance will conduct
> AC current up to as much as 30mA during the electrical strength test.
> Could someone please explain the reasoning for not allowing the
> 2250VDC electrical strength test?
> Thanks
> Bob Lappin
> Tyco Electronics