Joe, I don't have much technical to add but was wondering why you are looking into this standard. Have you customers that are asking for this requirement to be met or is it simply a planning exercise? If it's customer-driven, could you share what type of customer (ILEC, PTT, North America, European, Asian, etc.)?
I haven't seen this standard being used at all but I'm presently focussed on North America Service Provider requirements. BTW I agree with the comments that GR-1089 compliant products have proven to be extremely robust in the real-world. Cheers, Marko From: j...@aol.com [mailto:j...@aol.com] Sent: Thursday, April 17, 2003 12:54 PM To: t...@world.std.com; emc-p...@majordomo.ieee.org Subject: Lightning coordination in K.20 (2000) versus GR-1089 Hello All: I have been studying the new 2000 edition of K.20, "Resistibility of Telecommunication Equipment Installed in a Telecommunication Centre to Overvoltages and Overcurrents." There appears to be an important change >from the previous edition that will have a big impact on line interface design. I would like to get some feedback on whether I am understanding this properly. The change that concerns me is that for test 2.1.2 (4000 volt surge on twisted pair phone lines), K.20 now requires that the primary protector *must* operate. If there is any kind of secondary overvoltage protection internal to the equipment under test (EUT), requirement 2.1.2 pretty much forces the EUT to contain series resistors in front of the internal protection. Otherwise, the internal protection will prevent the external primary protector from operating. The requirement for the primary protector to operate can be waived if the protection internal to the EUT itself meets the requirements for a primary protector. However, this includes passing the test of 2.1.5 with vaguely specified surges of 1000 amps per wire and (presumably) open circuit voltages of 4000 volts. I note that in Telcordia GR-1089, the requirement to coordinate with the primary protector can be waived if the EUT can survive a 10x1000 uS, 100 amp surge (clause 4.6.7.1 of the 2002 edition). This requirement is fairly easy to meet without using series resistors. I find it interesting that series resistors have never been required for compliance with GR-1089, which itself is a pretty rigorous standard, nor were they required for previous editions of K.20. Now, it appears that manufacturers must decide at the outset whether their GR-1089 compliant products might ever go into a market where K.20 compliance is required. If so, the resistors have to go in the design. The series resistors needed to pass the new K.20 requirement are not ordinary resistors. Typically, they are large, wirewound, surge tolerant, flameproof resistors with steady state ratings of several watts. Two of these per port on a high density, multiport board is a big hit on board area. Furthermore, the added resistance is very detrimental to some types of DSL transmission. In other words, this change in K.20 looks like it will have a big impact on line interface design. My questions are as follows: 1) Is my understanding of the new coordination requirement in K.20 correct? 2) Is there a simpler way to comply with the requirement other than using series resistors? 3) Has there been any industry feedback to the ITU complaining about the coordination requirement as presently written? 4) Is there evidence that the 10x1000 uS, 100 amp waiver in GR-1089 is inadequate, justifying the much more stringent waiver requirement in K.20? Any and all comments on the above would be most welcome. I'm just trying to make sense out of the new requirements. Joe Randolph Telecom Design Consultant Randolph Telecom, Inc. 781-721-2848 j...@randolph-telecom.com http://www.randolph-telecom.com 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: davehe...@attbi.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
