Hi Piotr USB circuit is internal circuit. There are no transients expected on USB. Clause 5.4.11 is not applicable for power supply with USB output.
Paired conductor is a telecommunication network that we had in old times (analogue network, ISDN,...). I hope this helps. If you need more info, you can contact me. Best regards, Boštjan -----Original Message----- From: Piotr Galka <piotr.ga...@micromade.pl> Sent: Tuesday, May 7, 2024 5:40 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: [PSES] IEC 62368-1: To understand chapter 5.4.11 CAUTION: This email originated from outside of our organisation. Do not click links or open attachments unless you recognise the sender and know the content is safe. Trying to understand 62368-1... I have got laptop with type A power supply so it looks being not excluded from 5.4.11 by rules in 5.4.11.1. For me USB are external circuits indicated in Table 14, ID numbers 1 and 2 (I think USB is 'Paired conductor', but even not it certainly is 'Any other conductors'). The note in Table 14 about not taking into account transients for external circuits installed wholly within the same building is only about transients so I think it doesn't make USB being not indicated in table. USB cable can be used to connect laptop to printer and in printer USB can be earthed, I think. Dos this means that according to first sentence of 5.4.11.2 each USB port in this laptop should be separated from its other USB ports? I don't believe there is such requirement. My real problem to understand is as follows: Typical access controller have several not separated from each other inputs (several RFID reader inputs, door state control input, tamper inputs and others). I need to understand if the access controller powered from (external to it) 12V DC buffered (= having accu in it) supply is permanently connected equipment or not? To disconnect it from 12V supply you need tools, to disconnect 12V supply from mains you need tools, but 12V supply has isolation in it so access controller is not electrically connected to mains and 3.3.3.4 says about needing tools to disconnect from mains (if something is not connected than tools are not needed to make it being disconnected, I think). Being permanently connected equipment is the easiest way for controller to be excluded from 5.4.11. But if it is not permanently connected than its inputs are in the same situation as laptop USB ports I described first as more common to everyone. What I miss or wrongly understand? Regards Piotr Galka P.S. Last month free time I spend browsing about 2800 EMC-PSTC posts collected by my mail program for few years. - ---------------------------------------------------------------- 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-PSTC@LISTSERV.IEEE.ORG All emc-pstc postings are archived and searchable on the web at: https://www.mail-archive.com/emc-pstc@listserv.ieee.org/ Website: https://ewh.ieee.org/soc/pses/ Instructions: https://ewh.ieee.org/soc/pses/list.html (including how to unsubscribe) List rules: https://ewh.ieee.org/soc/pses/listrules.html For help, send mail to the list administrators: Mike Sherman at: msherma...@comcast.net Rick Linford at: linf...@ieee.org For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> _________________________________________________ To unsubscribe from the EMC-PSTC list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1 - ---------------------------------------------------------------- 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-PSTC@LISTSERV.IEEE.ORG All emc-pstc postings are archived and searchable on the web at: https://www.mail-archive.com/emc-pstc@listserv.ieee.org/ Website: https://ewh.ieee.org/soc/pses/ Instructions: https://ewh.ieee.org/soc/pses/list.html (including how to unsubscribe) List rules: https://ewh.ieee.org/soc/pses/listrules.html For help, send mail to the list administrators: Mike Sherman at: msherma...@comcast.net Rick Linford at: linf...@ieee.org For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> _________________________________________________ To unsubscribe from the EMC-PSTC list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1
