In my experience (and opinion), only slightly more than 15 watts is necessary to raise plastic material to ignition temperature.
If a MOV is used as a SPD, then it should only operate (be conductive) in the event of a transient over-voltage. If the transient event is the 1.2x50 waveform, the MOV should conduct for about 100-500 usecs. How long before the MOV returns to quiescent resistance? I ask this question because the recovery time will determine the heating power dissipation (from the mains voltage). Rich -----Original Message----- From: Ralph McDiarmid [mailto:ralph.mcdiar...@schneider-electric.com] Sent: Friday, November 17, 2017 10:05 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Regulatory requirements for MOVs placed line-to-ground on AC mains ports? I wonder if a 1A fuse would protect against MOV flameout just as well as a 100mA, if these MOV fail as an avalanche. (get hotter = more leakage) I've seen some standards use 240VA (assume 240W) as a power limit for protection against fire. However, I wonder if a MOV could burn nicely at say 0.5A without further increase in current. Ralph McDiarmid Product Compliance Engineering Solar Business Schneider Electric - ---------------------------------------------------------------- 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 <emc-p...@ieee.org> 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 <sdoug...@ieee.org> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com>