Hi folks; I agree that 62368 attempts to allow for more flexibility the process of designing a safe product, but in the specific case of fire enclosures there is in fact a considerable impact where some existing product can not be certified to the new standard without significant product redesign. Where 60950 only required compliance with clause 4.6.1's 5 degree projection rule, and allowed for as much as 5mm side openings, 62368 (where PIS's are within 15mm of ventilation openings in the fire enclosure) can require 3mm openings (depending on where in the expanded fire cone your openings fall). All other things remaining equal, you'd have to then decide between: -Having smaller openings with a resultant increase in thermal impedance (which will probably result in faster/noisier fans with more power consumption and lower operational lifetime) -Physical changes to the enclosure; growing the enclosure to pull the ventilation openings away from components (doing this on an ITE product may put you outside of the desired rack envelope), -Pulling the PCB back 15mm from the sides (physical designers will probably say that that it is not possible to keep the same functionality on a PCB when you've chopped off 15mm from the front and rear) The standard does allow for you to do component-level testing but with hundreds or thousands of components on PCB edges, this is not practical for some existing products.
-Ken On Wed, Jun 29, 2016 at 1:27 PM, Ted Eckert < [email protected]> wrote: > Hello Brian, > > > > This is a fairly simplistic view, but it’s the best I can do without > copying whole sections of the standards. It takes some time to learn the > new standard, but it may be well worth getting a copy to go over if you > will be using it in the future. > > > > IEC 60950-1 has requirements that go back to the days when transformers > and other components were sealed with waxes and varnishes. There are other > assumptions based on materials that used to be common but are now rarely > used. Many of the fire enclosure requirements were based on the assumption > that these materials could melt, catch on fire and drip out of the > enclosure. The requirements are partly based on the concept of looking at > the failure modes of the past and designing them out. > > > > IEC 62368-1 carries over many of the IEC 60950-1 fire enclosure > requirements as an option for compliance, but there are options to use > other constructional requirements that could give designers more > flexibility. Potential ignition sources are determined based on either > energy levels or other factors such as arcing. These potential ignition > sources must be provided protection, but it can be handled differently. You > will need to look at the standard to learn about concepts such as the fire > cones. Designers have more options for ways to isolate ignition sources. > They can have separation through barriers or distance. It’s not easy to > describe, but the designer should be able to do things that were not > previously allowed. There are certainly more options that allow for better > airflow and cooling that would have been difficult under IEC 60950-1. The > IEC 60950-1 requirements are included partly to make it easier to ensure > that IEC 60950-1 fire enclosures will meet IEC 62368-1 without going > through more work. However, if you are willing to do the work, you will see > that there is more flexibility in the design options if you use the new > requirements over the old. > > > > Ted Eckert > > Microsoft Corporation > > > > The opinions expressed are my own and do not necessarily reflect those of > my employer. > > > > *From:* Kunde, Brian [mailto:[email protected]] > *Sent:* Wednesday, June 29, 2016 9:24 AM > *To:* [email protected] > *Subject:* Re: [PSES] [BULK] Re: [PSES] Fire requirements in standards > > > > IBM Ken, > > > > My main interest at this time is with the fire enclosure. Our products > fall under the 61010-1, and it’s been years since I have read 60950, but I > can see where improvements in the constructional requirements in a fire > enclosure could be made. It seems our mechanical engineers sometimes > struggle to understand the requirements of Fire Enclosure, RF Enclosure, > Limit Access for electric shock, etc.. 61010-1 always seems to be lagging > so I was hoping to learn as much about future improvements as I can to give > more time to train our engineers. > > > > Thanks, > > The Other Brian > > > > *From:* IBM Ken [mailto:[email protected] <[email protected]>] > *Sent:* Wednesday, June 29, 2016 11:32 AM > *To:* Kunde, Brian > *Cc:* [email protected] > *Subject:* [BULK] Re: [PSES] Fire requirements in standards > *Importance:* Low > > > > Hi Brian; Do you mean specifically the changes to the fire enclosure > requirements or the overall differences between 60950 and 62368? If it's > the latter, ECMA TR/106 might be helpful (but be forewarned, this document > compares 60950 to the 1st edition of 62368). The best part is that it's > free! > http://www.ecma-international.org/publications/files/ECMA-TR/ECMA%20TR-106.pdf > > > > On Wed, Jun 29, 2016 at 8:53 AM, Kunde, Brian <[email protected]> > wrote: > > This subject is very interesting to me. If I wanted to know more, is > getting a copy of 62368-1 worth reading or will I have to wait for the > proposed changes to 60950-1 to come out, or what do you recommend? Are the > proposed changes quite large or can they be summarized? What are the weak > areas of the current construction requirements? I would like to inform our > mechanical people as soon as possible of changes like these. > Regards, > The Other Brian > > > -----Original Message----- > From: Richard Nute [mailto:[email protected]] > Sent: Tuesday, June 28, 2016 3:23 PM > To: [email protected] > Subject: [PSES] Fire requirements in standards > > > During last TC 108 meeting there was no real > consensus > > about this topic. Also there was an issue raised > that fire > > enclosure of some product will fail requirement > of new > > standard while it was OK for IEC 60950-1 and > they will > > make a proposal to change the requirement in the standard. > > This is true. A new standard implies that some aspects of the old > standard are inadequate. > > 62368-1 is better at preventing fires and preventing escape of fires than > 60950-1. Changing back to 60950-1 means continued fire incidents. I have > said many times that fire is our biggest problem. See the weekly recall > list from In Compliance magazine. > > > Best regards, > Rich > > - > ---------------------------------------------------------------- > 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 > > 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 <[email protected]> > Mike Cantwell <[email protected]> > > For policy questions, send mail to: > Jim Bacher: <[email protected]> > David Heald: <[email protected]> > > ________________________________ > > LECO Corporation Notice: This communication may contain confidential > information intended for the named recipient(s) only. If you received this > by mistake, please destroy it and notify us of the error. Thank you. > > > - > ---------------------------------------------------------------- > 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 > > 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 <[email protected]> > Mike Cantwell <[email protected]> > > For policy questions, send mail to: > Jim Bacher: <[email protected]> > David Heald: <[email protected]> > > > ------------------------------ > *LECO Corporation Notice:* This communication may contain confidential > information intended for the named recipient(s) only. If you received this > by mistake, please destroy it and notify us of the error. Thank you. > > - > ---------------------------------------------------------------- > > 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 > > 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 <[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.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 <[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.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 <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
