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]>
