Re: [PSES] fusing outputs of small power supplies

[Doug Powell]

Bob, The quickest way to determine the need for output fusing is to do the test. That is a short to the output should not result in a hazard such as spread of fire, electric shock, ejecting of parts, lifted circuit traces, melted insulation, etc.   You use the word small, but 4 x 24= 816 watts.   By the reckoning of most safety standards ‎this is not low energy, meaning you can achieve ignition.   Thanks, - doug Douglas Powell http://www.linkedin.com/in/dougp01   From: Bob LaFrance Sent: Tuesday, December 23, 2014 11:39 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Reply To: Bob LaFrance Subject: [PSES] fusing outputs of small power supplies Greetings,   I am curious to know what guidelines to use when fusing power supplies.  I have a machine with some small 4amp 24v power supplies.  I have placed breakers on the input side of supplies.  I don’t know if the current limit circuits within the power supply can be expected to protect output wiring.  I am mainly concerned with NFPA 7 & NEC, but I would like to hear UL or IEC thoughts on the subject.  The power supply manufacturers I have asked don’t seem to know – that struck me as very odd.   Many years ago I worked for a manufacturer of motor drives.  We developed a software implementation of a motor overload relay and got UL 508 blessing.  I am looking for similar arrangement.   Thank you and Merry Christmas.     Bob N9NEO     - ---------------------------------------------------------------- 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> - ---------------------------------------------------------------- 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>