Doug, The ony experience I ever had with "bad" fuses blowing prematurely was a soldered-in picofuse laying across a heavy copper trace on a PCB. This trace was retaining enough heat after soldering to weaken the fuse, causing premature failure in the field. Raising the body of the fuse off the board solved the problem.
Incidently, the problem was caught early through statistical analysis of field returns. Scott Lacey P.S.: It is well known in the automotive field that the old glass tube fuses often failed prematurely due to repeated stress and vibration. The newer blade type fuses are far more reliable. On 23 May 2003 at 16:56, POWELL, DOUG wrote: > > Hello all, > > Recently, in my company, we've been discussing what exactly > constitutes a good or bad fuse. In this industry we often hear that > the trouble with a defective product was, "the fuse was bad." I > occurred to me that the fuse is not bad, it performed exactly > intended. In fact if the problem that caused the fuse to "operate" is > still present, then the fuse is still good even though it is now an > open circuit. The only time it can be a bad fuse is if it did not > operate, resulting in shock or a fire. > > I have now have my ears tuned-in to this concept of a "bad fuse" and > find it is commonly used all over the industry. In fact you can go to > any number of websites that provide trouble shooting notes, and find > instructions on how you can measure a bad fuse from a good fuse using > an Ohm meter, photos included. And some of these instructions are from > reputable manufacturers. Another term often used is "defective fuse", > which in some way sounds more scientific, but is still fundamentally > wrong. > > I recently saw a newspaper article that gave the explaination why > electrical service was lost for over 100,000 people as a bad fuse. An > investigation was under way to determine why the fuse went bad. This > is a little like hearing the technologically uninitiated say "it must > be a short somewhere", when the television set stops working. > > Maybe I am finicky, but this affects how companies view real product > defects. When the "defect" is the bad fuse, then the real problem may > be covered up. Often the answer is, increase the fuse size to prevent > nuisance trips. The risk, of course, is that for every incremental > increase in fuse value, you increase the risk of fire proportionally. > > Any thoughts or experiences? > > BTW - To all US citizens in the group, have a relaxing Memorial Day > weekend. > > > -doug > > Douglas E. Powell > Regulatory Compliance Engineer > Advanced Energy Industries, Inc. > Fort Collins, CO 80535 USA > > _______________________________________________________________ > This message, including any attachments, may contain information > that is confidential and proprietary information of Advanced > Energy Industries, Inc. The dissemination, distribution, use > or copying of this message or any of its attachments is > strictly prohibited without the express written consent of > Advanced Energy Industries, Inc. This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
