True enough. However I have seen when MOVs have been directly connected to earth when Recognized using UL 1449. If not, there are schemes where spark gaps are placed in series to limit leakage. Spark gaps do have their own special concerns.
-doug http://www.linkedin.com/in/dougp01 -----Original Message----- From: Alexey Musin <[email protected]> Date: Tue, 25 Sep 2012 08:23:24 To: <[email protected]> Reply-To: Alexey Musin <[email protected]> Subject: Re: [PSES] MOV failure detection Hi, Doug, I.e., Phoenix Contact uses a thermo-fuse, heated from failed MOV. http://stevenengineering.com/tech_support/PDFs/67PT.pdf Please, look at figure 19 > Voltage sensing the fuse is useful on any line which has enough voltage with > respect to earth. The MOV tied to the neutral is much more difficult to > detect in this way. However, I would venture to say that this MOV is not > subjected to so many impulses as the other. In my practice the using of MOVs to ground is prohibited due to their leakage currents. Best regards, Alex - ---------------------------------------------------------------- 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]>
