Re: [8023-POEP] 802.3af Isolation 33.4.1
Thanks David,
I guess it worth checking again.
Yair
-----Original Message-----
From: David Law [mailto:David_Law@xxxxxxxxxxxx]
Sent: Thursday, April 28, 2005 11:35 AM
To: Yair Darshan
Cc: STDS-802-3-POEP@xxxxxxxxxxxxxxxxx
Subject: RE: [8023-POEP] 802.3af Isolation 33.4.1
Hi Yair,
Firstly I have to prefix the following by paraphrasing our esteemed
Study
Group chair and say that I don't pretend to be an expert on IEC 60950,
nor
do I play one on TV. That being said I agree with you that the
difference
between the IEEE Std 802.3af-2003 isolation requirements compared with
other IEEE 802.3 MAU/PHYs is something I personally find odd.
Due to that, and the maintenance work mentioned in the reply to comment
#88, I've actually been looking into this area over the last few weeks -
hence why I was able answer Bob so quickly when he first sent his
e-mail.
Based on this work, and with the help of a others, I intend to make a
presentation on this subject at the upcoming May interim session.
Bets regards,
David Law
"Yair Darshan" <YairD@xxxxxxxxxxxxxx> wrote on 22/04/2005 13:15:35:
> Hi David,
> Yes you are correct this was the reason for excluding the 2250Vdc
> option, however it is worth checking it again since technically it
> doesn't make sense.
> Checking 1500Vac 50-60Hz and checking with 2250Vdc is technically the
> same unless the EN60950 wish to check the ac current through the
> capacitors and insulation which can not be done with DC?
> Yair
> -----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 11:30 PM
> To: STDS-802-3-POEP@xxxxxxxxxxxxxxxxx
> Subject: Re: [8023-POEP] 802.3af Isolation 33.4.1
> Hi Bob,
> I had a look through the comment database and I would have thought
that
> comment #88 on page 22 would be of the most interest
>
[http://www.ieee802.org/3/af/comments/d4.0/P802_3af_D4_0_all_final.pdf#P
> age=22].
> It seems to be saying that subclause 6.2 of IEC 60950-1 only includes
> two
> tests, a AC test and a impulse tests, and the suggestion therefore
that
> subclause 33.4.1 should be aligned to this. The text in the response
> seems
> to indicate acceptance of this as it doesn't list the DC test.
> Best regards,
> David Law
>
> > From: Lappin, Bob <rlappin@xxxxxxxxxxxxxxxxxxx>
> > Date: Apr 21, 2005 5:09 PM
> > Subject: Re: [8023-POEP] 802.3af Isolation 33.4.1
> > To: STDS-802-3-POEP@xxxxxxxxxxxxxxxxx
> >
> > 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