Hi Steve:
I work mostly with the 60950-1 and 62368-1 standards for ITE, so I’m not familiar with the details of the requirements in 61010-1. That being said, I’ve seen many cases where someone misinterpreted the creepage/clearance/dielectric requirements in 60950-1 and 62368-1, not realizing that their specific configuration was exempt from those requirements. So, I’d like to have more details on the specific requirement that concern you, and the specific circuit where you are trying to apply this requirement. Is the 100 Vdc secondary fully floating with respect to the ground at the AC mains, or is it referenced to the AC mains ground? Does the AC mains connection use an ordinary “Pluggable Type A” plug or is it hardwired? If it uses a Type A plug, does that plug have a ground pin? These are just some of the factors that can affect how the isolation requirements apply to this specific design. If the AC mains ground is obtained from a grounded Type A plug, there is a fault scenario that might be behind the requirement that concerns you. This is case where the presumed ground in the AC outlet is missing, or the user has installed a “cheater adapter” to convert the 3-prong plug to a 2-prong plug. In this case the ground node in the equipment becomes a floating node, which creates certain potential scenarios that might create the need for the requirement that concerns you. I agree with you that it’s best to always make sure that understand the rationale behind any requirement that is giving you trouble. Once you know the rationale, you will better understand whether the requirement should apply to your specific application. Joe Randolph Telecom Design Consultant Randolph Telecom, Inc. 781-721-2848 (USA) <mailto:[email protected]> [email protected] <http://www.randolph-telecom.com/> http://www.randolph-telecom.com From: Steve Brody [mailto:[email protected]] Sent: Thursday, December 1, 2022 3:51 PM To: [email protected] Subject: [PSES] Secondary creepage/clearance I have a client who has a secondary pwb that has traces and vias that may have 100 vdc on them adjacent to ground. Per 61010-1 there is a requirement for spacing and/or dielectric test, both depending on what the mains voltage is. The question is why is the mains voltage a consideration or concern if the 100vdc secondary voltage is several layers of impedance and circuitry from the mains? Is it a concern that a surge on the mains would trickle down to the secondary circuit, or is there another reason/rationale? I suggested that a dielectric test per Table 6 [in A1] would suffice and put the issue to rest for this product, but the question from the designers remains as to why is it a concern in the standard of what the mains voltage is. Is there anything in the standard, that I haven't found, that does not require Table 6 to be followed if there is no way for a mains surge to impact the secondary voltage? I look to the experts for an explanation. Thanks, Steve Brody [email protected] <mailto:[email protected]> C - 603 617 9116 - ---------------------------------------------------------------- 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] <mailto:[email protected]> > All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html 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: Mike Cantwell <[email protected] <mailto:[email protected]> > For policy questions, send mail to: Jim Bacher <[email protected] <mailto:[email protected]> > David Heald <[email protected] <mailto:[email protected]> > _____ To unsubscribe from the EMC-PSTC list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC <https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1> &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 <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html 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: Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]> _________________________________________________ To unsubscribe from the EMC-PSTC list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1
