I read in !emc-pstc that [email protected] wrote (in <39.45102936.2d826 [email protected]>) about 'Wide Voltage Range ITE Product with a 250 V 3.0 / 3.15 A fuse' on Thu, 11 Mar 2004:
>So far I do not recall a discussion of why the fuse has failed in the >first place. If this is due to some foreseeable external event (such as >shorting the wires to loudspeakers) then it is understandable why the >fuses would be user replaceable. Shorting loudspeakers is such a common event that hardly any designs use fuse protection for this fault now. It's difficult anyway; FF fuses may be required and they are not readily available retail as replacements. Instead, either a relay disconnection (if the time required can be accepted) or electronic current limiting is used (together with a measure of load-line protection, allowing for load reactance). This means that for many products within the scope of IEC 60065, no user-accessible fuse is necessary, thus overcoming by elimination the problem of whether replacing a fuse by one of higher (or otherwise incorrect) rating is 'foreseeable misuse'. -- Regards, John Woodgate, OOO - Own Opinions Only. The good news is that nothing is compulsory. The bad news is that everything is prohibited. http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ieee-pses.org/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
