In the case of IEC 61010-1 Ed 3, it is possible to reduce clearance requirements utilizing Annex K.
In another case, say you have a brick power supply approve for use in OV Cat II but your application has an extended environmental condition of OV Cat III. In order to use this power supply, you must reduce the Category by one step. MOVs are just one possibility for achieving this. Of course, use of MOVs also has a certain added concerns that must be addressed. Doug Douglas E Powell http://www.linkedin.com/in/dougp01 http://www.linkedin.com/in/dougp01 -----Original Message----- From: Richard Nute <[email protected]> Date: Sat, 15 Dec 2012 11:08:53 To: <[email protected]> Reply-To: Richard Nute <[email protected]> Subject: [PSES] Why use an MOV? Presumably, the MOVs in question are connected line to neutral. I would expect the designer would design his primary circuit to withstand the normally-expected 1500 V transient. Why use an MOV??? Best wishes for the holiday season, 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://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]>
