I've been digesting the feedback and distracted by other pressing issues; this has been a great discussion.
I understand that "to ensure interoperability, both the PSE and PD devices must comply with the IEEE802.3af standard. A valid IEEE802.3af PSE device can deliver a maximum power of 15.4W per RJ-45 port and a valid IEEE802.3af PD device can consume a maximum power of 12.95W. Before applying power, the PSE must probe the PD and determine if a valid PD device is connected. The PD device must, in turn, exhibit a valid detection and classification signature prior to drawing power from the PSE. A valid PD detection signature is 25k and valid PD classes are Class 0 through Class 4." I am curious about the 15.4W PSE requirement. I have an idea; does anyone know the committee's rationale? Best regards, Don 561 912 6440 From: [email protected] [mailto:[email protected]] On Behalf Of Peter Tarver Sent: Thursday, March 26, 2009 11:28 PM To: [email protected] Subject: RE: PoE injectors On 26 Mar 2009 at 9:00, Umbdenstock, Don wrote: > > My apologies for thinking out loud "if a PD can present up > to a 13 W load, then the 25k handshake cannot be part of the > load, but rather is restricted to a handshake circuit. So > the question is whether there is a spec for current limiting > for PSE? If a PSE is by definition current limited, and AHJs > know this, then LPS or NEC Class 2 marking wouldn't seem to > be necessary. LPS, NEC Class 2, et al, all have voltage, current and possibly overcurrent protection and power limitations placed on them **at the source**. The load becomes irrelevant to such circuit designations. > The reason for the series of PoE comments is to anticipate > the needs of the AHJs. Is the above conclusion a logical > argument for anticipating questions from an AHJ? PoE, to my knowledge, isn't recognized by AHJs. They may try to impose a TNV type of designation, for their purposes, which they do recognize (I've heard of at least one case of this). Peter Tarver [email protected] - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]> - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
