To Rich, Doug and All Members, I just got clarification from UL that opening of a trace during Overvoltage Tests is OK as long as unit passes either the Leakage and Dielectric Tests. However, opening of a trace during component abnormals would be considered an unacceptable result.
Thank you everyone for all the input. Date sent: Tue, 5 Jan 1999 16:08:51 -0800 (PST) From: Rich Nute <ri...@sdd.hp.com> To: dmck...@corp.auspex.com Subject: Re: UL1950 Overvoltage Tests Copies to: emc-p...@majordomo.ieee.org (Product Safety Technical Committee) Send reply to: Rich Nute <ri...@sdd.hp.com> > > > Hi Doug: > > > > Isn't this a variation of using the traces as a fusing element > > instead of using a real fuse? > > Not necessarily. > > In Peter's situation, the test was that of the integrity > of the insulation between the TNV circuit and the other > circuits. > > So, if the "fused" trace did not bridge the insulation, > then there should be no consideration that the trace was > being used as a fuse. It is simply a failure, and a > particular kind of failure -- open-circuit. > > Many, many fault-condition (abnormal) tests end up with an > open circuit. We don't treat all component open-circuits > as fuses. So, why should we treat an open trace as a fuse? > > It is unlikely that fusing of a trace will bridge a safety > insulation. On the other hand, fusing of a transformer > winding wire may be associated with enough heat to damage > the solid safety insulation within the transformer! > > On the other hand, if the fusing of the trace should > prevent an overheating situation (fire?), then the trace > probably should be evaluated for its fusing action. > > So, one needs to understand the nature of the test in > order to evaluate the results of the test to determine > whether the opening of a trace is a fusing action as > opposed to simply the end of a fault-condition test. > > > Best wishes for the New Year, > Rich > > > > ------------------------------------------------------------- > Richard Nute Product Safety Engineer > Hewlett-Packard Company Product Regulations Group > AiO Division Tel : +1 619 655 3329 > 16399 West Bernardo Drive FAX : +1 619 655 4979 > San Diego, California 92127 e-mail: ri...@sdd.hp.com > ------------------------------------------------------------- > > > > > > --------- > This message is coming from the emc-pstc discussion list. > To cancel your subscription, send mail to majord...@ieee.org > with the single line: "unsubscribe emc-pstc" (without the > quotes). For help, send mail to ed.pr...@cubic.com, > j...@gwmail.monarch.com, ri...@sdd.hp.com, or > roger.volgst...@compaq.com (the list administrators). > PETER S. MERGUERIAN MANAGING DIRECTOR PRODUCT TESTING DIVISION I.T.L. (PRODUCT TESTING) LTD. HACHAROSHET 26, P.O.B. 211 OR YEHUDA 60251, ISRAEL TEL: 972-3-5339022 FAX: 972-3-5339019 E-MAIL: pe...@itl.co.il Visit our Website: http://www.itl.co.il --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
