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
