Thanks ! A very clear answer. Not the one I wanted, but clear.
>________________________________ > From: Boštjan Glavič <[email protected]> >To: Bill Owsley <[email protected]> >Cc: "[email protected]" <[email protected]> >Sent: Saturday, May 11, 2013 12:29 PM >Subject: Re: [PSES] safety 60950 and surge suppression circuits > > >Hi Bill, > >You can use MOV (VDR) primary to PE as long as you have reliable earth. >Reliable earth is considered for pluggable equipment type B or permanently >connected equipment. For pluggable equipment type A, you would need additional >earthing point, what is usually not acceptable for clients. > >Unfortunately, if you use combination VDR + GDT, GDT needs to comply with >requirements for basic insulation (1500Vac) for any kind of equipment. I know >the requirement is strange but also new hazard based standard 62368-1 has the >same requirement. > >GDT alone cannot use bridge basic insulation primary to PE. > >But please note, this is valid for primary circuit only. For secondary >circuits no such requirements are applicable. > >Best regards, >Bostjan > > > >On 11. maj 2013, at 18:09, "Bill Owsley" ><[email protected]<mailto:[email protected]>> wrote: > >I'm running into a dilemma. Not being a Safety Engineer myself, but rubbing >elbows with them... >On a piece of ITE equipment, I need some surge suppression for worldwide >markets with one annoying requirement for 4 kV, otherwise just 2 kV line to >earth, and using either plugable cords or permanent connection, whichever is >worse. >Now the Safety guys tell me that MOV's alone cannot bridge the insulation >(Basic or Functional, I forget.) between primary and earth, when using one of >power cable options mentioned above. >But a proper qualified (GDT) gas discharge tube can do the bridging. So we >figured to use them in series. >On a quick and dirty bench test it works to 4 kV. >Then the Safety guys pull out the rest of the story and point out 5.2.2 which >seems to indicate that the GDT is to meet the Hi-Pot test, 1500 vac. >Previously, section, 1.5.9.4 (?) indicates that the surge protection devices >can be removed during the Hi-Pot test. >But now I have a Surge suppression circuit that has to withstand the same >Hi-Pot as the rest of the board. >Question is how does a surge protection circuit protect the board when it has >to meet the same Hi-Pot test? >In other words, when a surge comes along, which is going to break over first? >The surge protection or the board? >Is the purpose of surge suppression is to keep the clamped voltage below a >problem level? >What am I missing in this? > >Thanks... >- Bill > >- >---------------------------------------------------------------- > >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 > >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://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]<mailto:[email protected]>> >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]>> > >- >---------------------------------------------------------------- >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://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.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://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]>
