Randy and Duane Hello, I don't have my UL1459 handy, but if I recall correctly UL1459 also has the option of construction in lieu of testing or a combination of both construction and testing. Also UL1459 tests are similar to UL1950 except for the test equipment simulator fuse value, 1.6 A vs 2.0 A. Please correct me if I am wrong.
Also, I would like to take this opportunity to share with all treggers something I learnt over the past few years. A UL1950 3rd Edition modem (or other UL1950 3rd Ed. telecom device) can be acccepted in a UL1459 end-product (eg rack system) but a UL1459 compliant modem cannot be accepted in a UL1950 3rd Edition end- product unless additionally evaluated for construction and/or testing. Date sent: Tue, 26 Jan 99 17:08:19 EST To: <[email protected]> From: "Randolph Ivans" <[email protected]> Subject: re: Ul 1459 Test Question Send reply to: [email protected] > The tests are intended to deal with power system faults on the network. > These are known to happen and publications like UL1459, CSA225, > UL1950/CSA950 and Bellcore GR-1089-CORE all have requirements that address > this. In UL1459 the only option is testing. For your info, the test you > mention does have limiting....to 40A. I believe that 15ohm resistors are > used in series with the 600V source to accomplish this. > > Prior to the merging of the telecom and ite standards, modems typically > were not evaluated for overvoltage conditions. Even though the installed > base was not as large as telephones, and a lot were connected behind pbxs > etc., there still appeared to be little to suggest ite connected to teleco > lines were having problems. This led the standards development group to > look at the construction typically employed by modems at the time and the > result was a set of "construction requirements" that most felt would > deliver an equivalent level of safety as passing the overvoltage tests. > These made their way into the 3rd edition of Ul1950/CSA950. Another > significant change is that the UL1950 philosophy of being only an equipment > standard eliminated the "simulator fuse" that was intended to represent (if > it opened) damage to the network wiring. Only the equipment cord is a > concern and this can be addressed by using a min 26AWG size telecom wire. > > If you look at the flowchart included with the standard you can see the > left path is "construction" and the right path is "testing" and there are > various interconnecting paths allowing some construction and some testing. > > FYI, GR-1089 still requires testing and even requires the unit to be > functional after some of the tests. > > > > Randy Ivans > Underwriters Laboratories Inc. > Business Sector Coordinator > Telecommunications Industry > email: [email protected] > ------------- > Original Text > From: "Duane J. Marcroft" <[email protected]>, on 1/26/99 1:16 PM: > Hi Treg'rs > > I don't have a copy of UL 1459 and I'm having a problem trying to > understand why a particular UL test is being performed. Could I impose on > someone to explain what UL1459,59.5,b),1) is testing and why? > > The test is being performed on a modem DAA by a piece of automated > equipment. As a consequence the person performing the test is unable to > explain much about the test. > > The TIP & RING circuit being tested consists of a 300V Sidactor, two 4.7 > ohm resistors and a RJ-11. The resistors are series with T/P and are there > to limit current when Sidactor hits break-over point. > > The UL test is applying a longitudinal 600V @ 40A to TIP and RING via the > RJ-11, with modem on-hook. There is no current limiting in the test > equipment except a fuse. > > Heres whats happening: > > When the test is run the Sidactor, one of the resistors fails and current > limit fuse in test equipment blows. But, the DAA circuit does pass the > Part 68 transient test. > > Is this a valid test? I have designed many modems and never had to pass > this test before. Can someone please advise? > > Thank you in advance. > > Duane Marcroft > Telecom Consultant > 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: [email protected] Visit our Website: http://www.itl.co.il
