Mike, In addition to imposing NEBS requirements, carriers such as SBC, AT&T, etc., will typically complement NEBS with general equipment specifications which contain power requirements (among other requirements) for their own or for co-located equipment. A carrier's co-location requirements do not address equipment availability. Examples include: AT&T Network Services - Network Equipment Development Standards (NEDS), December 30, 1999; Bell Atlantic - RNSA-NEB-95-0003, Rev 10, Issued: January 26, 2000; SBC Local Exchange Carriers - Equipment Requirements TP76200MP, December 30, 1998
Often specified is a primary power source that is dual (A and B) -48 VDC. This, by itself, does not require dual-redundant power supplies or converters. If not otherwise specified, it may become more a matter of system availability calculations. A single high-MTBF power supply can result in a lower (poorer) system availability than dual-redundant, lower MTBF power supplies, provided that no system down time is incurred during the failure and subsequent replacement of one of the redundant supplies. This, of course, assumes field replaceable, hot swappable power supplies. Another useful industry standard for carriers is, ANSI T1.315-1994, Voltage Levels for DC-Powered Equipment - Used in the Telecommunications Environment - (ATIS/Committee T1), which specifies power sources, but is not concerned with equipment availability and redundant power supplies. I do not know of any NEBS requirement for dual redundant power supplies. Gerry Dooley Vivace Networks, Inc. -----Original Message----- From: nebs-appro...@world.std.com [mailto:nebs-appro...@world.std.com]On Behalf Of Scott Baer Sent: Tuesday, September 12, 2000 3:14 PM To: nebs@world.std.com; michael.prus...@spikebroadband.net Subject: Re: NEBS redundancy requirements Mike, I don't believe that you'll find any requirement in GR-63-CORE or GR-1089-CORE for dual-redundant power supplies. What you probably have is a specification specifying a "High Availability" system, which is often associated with the near-100% uptime that is expected of telecommunications facilities. The benefit of dual-redundant power is that it removes one opportunity for a single-point failure from your equipment shelf. NEBS is frequently required of telecommunications equipment if it is either (1) purchased by Bell South, SBC, Qwest, or Verizon, and/or (2) be placed in one of their central offices by a co-locator. So, NEBS and "High Availability" are often mentioned in the same breath. However, NEBS doesn't dictate your power supply architecture as to whether it is redundant or not. You may find it more cost-effective in some applications to consider a single high-MTBF power supply. Scott Baer ====================== Scott J. Baer, P.E. Product Compliance Engineer AG Communication Systems A Subsidiary of Lucent Technologies Michael Prussel wrote: > Greetings all - > > A question has come up regarding the need for dual-redundant power supplies > residing within a Compact PCI system chassis. One of our people claims this > feature ties to NEBS compliance. > > Is there a specific NEBS requirement(s) that would dictate dual redundant > power supplies? If so, where can I find it? > > Would a single high-MTBF power supply be an alternative way to meet such a > requirement? > > Thanks very much for your help. > > Mike Prussel > Regulatory Engineer > Spike Broadband Systems > Nashua, NH > michael.prus...@spikebroadband.net
