Re: [PSES] PoE Injectors
Thank you to all for the comments on PoE Injectors. Good to know of some of the pitfalls when using (re:supplying) these with a product. Not sure I want to sign up for the extra workload. On 10/20/2015 1:09 PM, Richard Jones wrote: I have also seen emission failures with IP devices using POE Injectors, if I remember correctly the emission margin dropped as you went up 10MHz, 100MHz to 1GHz. I would think that you would need to try a few different types to find a good one and of course unless you're working closely with the manufacturer there is no guarantee that what you test today will still pass tomorrow :-) Rich On Mon, Oct 19, 2015 at 6:06 PM, Doug Smith <mailto:d...@emcesd.com>> wrote: Hi Chas and the group, It was the design layout of the PCB of the POE, and it was easy to see (no PHY used). The magnetics may have played a part but the layout is terrible in some of these devices. They are not designed by engineers of any competence. In my article, I was very careful to make sure the end points of the Ethernet connection and cable were not a factor, described in the article. There is no PHY in this case, just inductors to inject the DC onto the Ethernet connection. No active circuitry was involved as I remember. Doug Department for Continuing Education Oxford, Oxfordshire, United Kingdom -- Doug Smith P.O. Box 60941 Boulder City, NV 89006-0941 TEL/FAX: 702-570-6108 /570-6013 Mobile: 408-858-4528 Email: d...@dsmith.org <mailto:d...@dsmith.org> Web: http://www.dsmith.org -- On Mon, 19 Oct 2015 21:29:14 +, "Grasso, Charles" mailto:charles.gra...@echostar.com>> wrote: Hello Doug – in your tidbit you indicated that the pwb layout was (likely) responsible for the increased emissions at the below 100MHz range. It has been my experience that when the magnetics are placed inside a connector, that the emissions are more influenced from the imbalance in the cores and assembly that the layout. Nowadays there is literally no ambiguity in the layout – the traces go from the phy in the SoC to the connector - that’s it! [I am assuming that the design guidelines from the connector/phy manufacturer are being followed] Also how do you isolate the influence of the cable in your measurements? After all the internal signal wires could be twisted differently as you move the cable... Y/N?? Best Regards Charles Grasso Compliance Engineer Echostar Communications (w) 303-706-5467 (c) 303-204-2974 (t) 3032042...@vtext.com <mailto:3032042...@vtext.com> (e) charles.gra...@echostar.com <mailto:charles.gra...@echostar.com> (e2) chasgra...@gmail.com <mailto:chasgra...@gmail.com> *From:*Doug Smith [mailto:d...@emcesd.com <mailto:d...@emcesd.com>] *Sent:* Sunday, October 18, 2015 1:49 PM *To:* EMC-PSTC@LISTSERV.IEEE.ORG <mailto:EMC-PSTC@LISTSERV.IEEE.ORG> *Subject:* Re: [PSES] PoE Injectors Hi Bill, Keep in mind that many POE adapters on the market will cause an emissions problem because they are poorly designed and unbalance the Ethernet pairs creating common mode currents. See my Technical Tidbit at http://www.emcesd.com/tt2011/tt080111.htm When you open some of them and look at the design, it is obvious they were not designed by engineers. Doug Department for Continuing Education Oxford, Oxfordshire, United Kingdom -- Doug Smith P.O. Box 60941 Boulder City, NV 89006-0941 TEL/FAX: 702-570-6108 /570-6013 Mobile: 408-858-4528 Email: d...@dsmith.org <mailto:d...@dsmith.org> Web: http://www.dsmith.org <http://www.dsmith.org> -- On Sun, 18 Oct 2015 18:50:30 +, Bill Owsley <00f5a03f18eb-dmarc-requ...@ieee.org <mailto:00f5a03f18eb-dmarc-requ...@ieee.org>> wrote: Somewhere in the references at the end, you might find which devices that these standards apply to. There are number of exceptions. And there may have been changes since doc was published. In the past I have emailed Victor with questions. - Bill *From:*Scott Douglas mailto:sdouglas...@gmail.com>
Re: [PSES] PoE Injectors
I have also seen emission failures with IP devices using POE Injectors, if I remember correctly the emission margin dropped as you went up 10MHz, 100MHz to 1GHz. I would think that you would need to try a few different types to find a good one and of course unless you're working closely with the manufacturer there is no guarantee that what you test today will still pass tomorrow :-) Rich On Mon, Oct 19, 2015 at 6:06 PM, Doug Smith wrote: > Hi Chas and the group, > > > > It was the design layout of the PCB of the POE, and it was easy to see (no > PHY used). The magnetics may have played a part but the layout is terrible > in some of these devices. They are not designed by engineers of any > competence. In my article, I was very careful to make sure the end points > of the Ethernet connection and cable were not a factor, described in the > article. > > > > There is no PHY in this case, just inductors to inject the DC onto the > Ethernet connection. No active circuitry was involved as I remember. > > > > Doug > > > > Department for Continuing Education > > Oxford, Oxfordshire, United Kingdom > > -- > > Doug Smith > > P.O. Box 60941 > > Boulder City, NV 89006-0941 > > TEL/FAX: 702-570-6108/570-6013 > > Mobile: 408-858-4528 > > Email: d...@dsmith.org > > Web: http://www.dsmith.org > > -- > > > > > > On Mon, 19 Oct 2015 21:29:14 +, "Grasso, Charles" < > charles.gra...@echostar.com> wrote: > > Hello Doug – in your tidbit you indicated that the pwb layout was (likely) > responsible for the > increased emissions at the below 100MHz range. It has been my experience > that when > the magnetics are placed inside a connector, that the emissions are more > influenced from > the imbalance in the cores and assembly that the layout. Nowadays there > is literally > no ambiguity in the layout – the traces go from the phy in the SoC to the > connector - > that’s it! [I am assuming that the design guidelines from the > connector/phy manufacturer > are being followed] Also how do you isolate the influence of the cable in > your measurements? > > > > After all the internal signal wires could be twisted differently as you > move the cable... Y/N?? > > > > > > Best Regards > > > > Charles Grasso > > > > Compliance Engineer > > > > Echostar Communications > > > > (w) 303-706-5467 > > > > (c) 303-204-2974 > > > > (t) 3032042...@vtext.com > > > > (e) charles.gra...@echostar.com > > > > (e2) chasgra...@gmail.com > > > > > > *From:* Doug Smith [mailto:d...@emcesd.com] > *Sent:* Sunday, October 18, 2015 1:49 PM > *To:* EMC-PSTC@LISTSERV.IEEE.ORG > *Subject:* Re: [PSES] PoE Injectors > > > > > > Hi Bill, > > > > > > > > Keep in mind that many POE adapters on the market will cause an emissions > problem because they are poorly designed and unbalance the Ethernet pairs > creating common mode currents. > > > > > > > > See my Technical Tidbit at http://www.emcesd.com/tt2011/tt080111.htm > > > > > > > > When you open some of them and look at the design, it is obvious they were > not designed by engineers. > > > > > > > > Doug > > > > > > > > Department for Continuing Education > > > > Oxford, Oxfordshire, United Kingdom > > > > -- > > > > Doug Smith > > > > P.O. Box 60941 > > > > Boulder City, NV 89006-0941 > > > > TEL/FAX: 702-570-6108/570-6013 > > > > Mobile: 408-858-4528 > > > > Email: d...@dsmith.org > > > > Web: http://www.dsmith.org > > > > -- > > > > > > > > > > > On Sun, 18 Oct 2015 18:50:30 +, Bill Owsley < > 00f5a03f18eb-dmarc-requ...@ieee.org> wrote: > > > > Somewhere in the references at the end, you might find which devices that > these standards apply to. > > > > There are number of exceptions. And there may have been changes since doc > was published. > > > > In the past I have emailed Victor with questions. > > > > - Bill > > > > > > > > > > > -- > > *From:* Scott Douglas > *To:* EMC-PSTC@LISTSERV.IEEE.ORG > *Sent:* Sunday, October 18, 2015 2:04 AM > *Subject:* [PSES] PoE Injectors > > > > > Hello All, &
Re: [PSES] PoE Injectors
Hi Chas and the group, It was the design layout of the PCB of the POE, and it was easy to see (no PHY used). The magnetics may have played a part but the layout is terrible in some of these devices. They are not designed by engineers of any competence. In my article, I was very careful to make sure the end points of the Ethernet connection and cable were not a factor, described in the article. There is no PHY in this case, just inductors to inject the DC onto the Ethernet connection. No active circuitry was involved as I remember. Doug Department for Continuing Education Oxford, Oxfordshire, United Kingdom -- Doug Smith P.O. Box 60941 Boulder City, NV 89006-0941 TEL/FAX: 702-570-6108/570-6013 Mobile: 408-858-4528 Email: d...@dsmith.org Web: http://www.dsmith.org -- On Mon, 19 Oct 2015 21:29:14 +, "Grasso, Charles" wrote: Hello Doug – in your tidbit you indicated that the pwb layout was (likely) responsible for the increased emissions at the below 100MHz range. It has been my experience that when the magnetics are placed inside a connector, that the emissions are more influenced from the imbalance in the cores and assembly that the layout. Nowadays there is literally no ambiguity in the layout – the traces go from the phy in the SoC to the connector - that’s it! [I am assuming that the design guidelines from the connector/phy manufacturer are being followed] Also how do you isolate the influence of the cable in your measurements? After all the internal signal wires could be twisted differently as you move the cable... Y/N?? Best Regards Charles Grasso Compliance Engineer Echostar Communications (w) 303-706-5467 (c) 303-204-2974 (t) 3032042...@vtext.com (e) charles.gra...@echostar.com (e2) chasgra...@gmail.com From: Doug Smith [mailto:d...@emcesd.com] Sent: Sunday, October 18, 2015 1:49 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] PoE Injectors Hi Bill, Keep in mind that many POE adapters on the market will cause an emissions problem because they are poorly designed and unbalance the Ethernet pairs creating common mode currents. See my Technical Tidbit at http://www.emcesd.com/tt2011/tt080111.htm When you open some of them and look at the design, it is obvious they were not designed by engineers. Doug Department for Continuing Education Oxford, Oxfordshire, United Kingdom -- Doug Smith P.O. Box 60941 Boulder City, NV 89006-0941 TEL/FAX: 702-570-6108/570-6013 Mobile: 408-858-4528 Email: d...@dsmith.org Web: http://www.dsmith.org -- On Sun, 18 Oct 2015 18:50:30 +, Bill Owsley wrote: Somewhere in the references at the end, you might find which devices that these standards apply to. There are number of exceptions. And there may have been changes since doc was published. In the past I have emailed Victor with questions. - Bill - From: Scott Douglas To: EMC-PSTC@LISTSERV.IEEE.ORG Sent: Sunday, October 18, 2015 2:04 AM Subject: [PSES] PoE Injectors Hello All, I am wondering if PoE injectors need to be ErP compliant? If so, what efficiency level? Does anyone know of any such injectors that are compliant? The injector would be used to power a product and not a switch, router, or access point. Any and all comments appreciated. Regards, Scott - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald: - 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 <emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-ps
Re: [PSES] PoE Injectors
Hello Doug – in your tidbit you indicated that the pwb layout was (likely) responsible for the increased emissions at the below 100MHz range. It has been my experience that when the magnetics are placed inside a connector, that the emissions are more influenced from the imbalance in the cores and assembly that the layout. Nowadays there is literally no ambiguity in the layout – the traces go from the phy in the SoC to the connector - that’s it! [I am assuming that the design guidelines from the connector/phy manufacturer are being followed] Also how do you isolate the influence of the cable in your measurements? After all the internal signal wires could be twisted differently as you move the cable... Y/N?? Best Regards Charles Grasso Compliance Engineer Echostar Communications (w) 303-706-5467 (c) 303-204-2974 (t) 3032042...@vtext.com (e) charles.gra...@echostar.com (e2) chasgra...@gmail.com From: Doug Smith [mailto:d...@emcesd.com] Sent: Sunday, October 18, 2015 1:49 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] PoE Injectors Hi Bill, Keep in mind that many POE adapters on the market will cause an emissions problem because they are poorly designed and unbalance the Ethernet pairs creating common mode currents. See my Technical Tidbit at http://www.emcesd.com/tt2011/tt080111.htm When you open some of them and look at the design, it is obvious they were not designed by engineers. Doug Department for Continuing Education Oxford, Oxfordshire, United Kingdom -- Doug Smith P.O. Box 60941 Boulder City, NV 89006-0941 TEL/FAX: 702-570-6108/570-6013 Mobile: 408-858-4528 Email: d...@dsmith.org<mailto:d...@dsmith.org> Web: http://www.dsmith.org -- On Sun, 18 Oct 2015 18:50:30 +, Bill Owsley <00f5a03f18eb-dmarc-requ...@ieee.org<mailto:00f5a03f18eb-dmarc-requ...@ieee.org>> wrote: Somewhere in the references at the end, you might find which devices that these standards apply to. There are number of exceptions. And there may have been changes since doc was published. In the past I have emailed Victor with questions. - Bill From: Scott Douglas mailto:sdouglas...@gmail.com>> To: EMC-PSTC@LISTSERV.IEEE.ORG<mailto:EMC-PSTC@LISTSERV.IEEE.ORG> Sent: Sunday, October 18, 2015 2:04 AM Subject: [PSES] PoE Injectors Hello All, I am wondering if PoE injectors need to be ErP compliant? If so, what efficiency level? Does anyone know of any such injectors that are compliant? The injector would be used to power a product and not a switch, router, or access point. Any and all comments appreciated. Regards, Scott - 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 mailto:emc-p...@ieee.org>> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas mailto:sdoug...@ieee.org>> Mike Cantwell mailto:mcantw...@ieee.org>> For policy questions, send mail to: Jim Bacher: mailto:j.bac...@ieee.org>> David Heald: mailto:dhe...@gmail.com>> - 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 <emc-p...@ieee.org<mailto:emc-p...@ieee.org>> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe)<http://www.ieee-pses.org/list.html> List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <sdoug...@ieee.org<mailto:sdoug...@ieee.org>> Mike Cantwell <mcantw...@ieee.org<mailto:mcantw...@ieee.org>> For policy questions, send mail to: Jim Bacher <j.bac...@ieee.org<mailto:j.bac...@ieee.org>> David Heald <dhe...@gmail.com<mailto:dhe...@gmail.com>> - This message is from the IEEE Product Safe
Re: [PSES] PoE Injectors
Hi Bill, Keep in mind that many POE adapters on the market will cause an emissions problem because they are poorly designed and unbalance the Ethernet pairs creating common mode currents. See my Technical Tidbit at http://www.emcesd.com/tt2011/tt080111.htm When you open some of them and look at the design, it is obvious they were not designed by engineers. Doug Department for Continuing Education Oxford, Oxfordshire, United Kingdom -- Doug Smith P.O. Box 60941 Boulder City, NV 89006-0941 TEL/FAX: 702-570-6108/570-6013 Mobile: 408-858-4528 Email: d...@dsmith.org Web: http://www.dsmith.org -- On Sun, 18 Oct 2015 18:50:30 +, Bill Owsley wrote: Somewhere in the references at the end, you might find which devices that these standards apply to. There are number of exceptions. And there may have been changes since doc was published. In the past I have emailed Victor with questions. - Bill - From: Scott Douglas Subject: [PSES] PoE Injectors Hello All, I am wondering if PoE injectors need to be ErP compliant? If so, what efficiency level? Does anyone know of any such injectors that are compliant? The injector would be used to power a product and not a switch, router, or access point. Any and all comments appreciated. Regards, Scott - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald: - 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 <emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <sdoug...@ieee.org> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher <j.bac...@ieee.org> David Heald <dhe...@gmail.com> - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] PoE Injectors
Somewhere in the references at the end, you might find which devices that these standards apply to. There are number of exceptions. And there may have been changes since doc was published.In the past I have emailed Victor with questions.- Bill From: Scott Douglas To: EMC-PSTC@LISTSERV.IEEE.ORG Sent: Sunday, October 18, 2015 2:04 AM Subject: [PSES] PoE Injectors Hello All, I am wondering if PoE injectors need to be ErP compliant? If so, what efficiency level? Does anyone know of any such injectors that are compliant? The injector would be used to power a product and not a switch, router, or access point. Any and all comments appreciated. Regards, Scott - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald: - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
[PSES] PoE Injectors
Hello All, I am wondering if PoE injectors need to be ErP compliant? If so, what efficiency level? Does anyone know of any such injectors that are compliant? The injector would be used to power a product and not a switch, router, or access point. Any and all comments appreciated. Regards, Scott - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
