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Re: [8023-POEP] Fwd: [8023-POEP] 802.3af Isolation 33.4.1



Hi Bob,

As far as I can recall the initial sponsor ballot draft D4.0 included the
2250V DC test and, as we can see in the comment archive, in the response
to draft D4.0 comment #88 it seems to be removed. It therefore seems to me
that the DC test was removed between the initial sponsor draft D4.0 and
recirculation ballot draft D4.1 - unfortunately that's the best I can do.

In respect to IEEE Std 802.3-2002, while I cannot give you any official
statement, as far as I can see the isolation test references are not to
subclause 6.2 of IEC 60950-1:2001 as you state, but instead are to
subclause 5.3.2 of IEC 60950: 1991.

Best regards,
  David



> From: Lappin, Bob <rlappin@xxxxxxxxxxxxxxxxxxx>
> Date: Apr 21, 2005 10:52 PM
> Subject: Re: [8023-POEP] 802.3af Isolation 33.4.1
> To: STDS-802-3-POEP@xxxxxxxxxxxxxxxxx

>
> Hi Dave,

> Yes I read #88 and understood that the isolation statement in the
> 802.3af was intended to align itself with the IEC60950.  I was hoping to
> see some explicit statement to remove the 2250VDC option that was part
> of the D3 revision of the 802.3af in Nov. 2001.

> Interestingly enough, the 802.3 specification allows 2250VDC isolation
> testing and references the same sub-clause 6.2 in the IEC60950
> specification.

> Thanks for your help.

> 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 2:30 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