The standard says:
The equipment, circuit diagrams and component specifications are examined to determine those fault conditions that might reasonably be expected to occur. The paper http://industrial.panasonic.com/www-data/pdf/AOC0000/AOC0000PE10.pdf explains that these types of components fail o/c, so my argument is that short-circuit failure mode is not "reasonably expected to occur". Regards Charlie -----Original Message----- From: John Woodgate [mailto:[email protected]] Sent: 17 November 2014 10:27 To: [email protected]<mailto:[email protected]> Subject: Re: [PSES] Surface mount resistors failing short circuit In message <[email protected]<mailto:[email protected]>>, dated Mon, 17 Nov 2014, Charlie Blackham <[email protected]<mailto:[email protected]>> writes: > >The NRTL insist on short-circuiting the single 560R current limiting >resistor and I am unable to find any evidence that thick-film or >thin-film surface mount resistors can fail short-circuit as they appear >to fail open-circuit They are citing the standard, which doesn't have an exception for not shorting SM resistors. It's probably too late to take them into account in 60950-1, but this should be considered for 62489-1, if it hasn't been already. Will the resistor manufacturers give assurances that S/C failures do not occur? -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk<http://www.jmwa.demon.co.uk> When I turn my back on the sun, it's to look for a rainbow John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - ---------------------------------------------------------------- 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://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 <[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://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 <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
