Brian, I have a copy of Issue 6, December 1997 and on page 1-1 there is a definition for device, unit, and serial system.
Device - Refers to a basic component (or part) listed in Table 11-1 (formerly Table A) of this document. {I believe these would be components like a transistor, resistor, capacitor, diode, etc.} Unit - is used herein to describe any customer replaceable assembly of devices. This may include, but is not limited to, circuit packs, modules, plug-in units, racks, power supplies, and ancillary equipment. Unless otherwise dictated by maintenance considerations, a unit will usually be the lowest level of replaceable assemblies/devices. {It is kind of ambiguous because they almost seem alike with one exception, the unit is multiple devices or a complete assembly} Serial System - Refers to any system for which the failure of any single unit will cause a failure of the system. {Think of several modules connected together in series, a power supply that powers a module that controls a tuner. If the module that controls the tuner dies then the tuner will not function. Therefore the whole system has failed.} As far as software tools for reliability, I have used Relex software to calculate the reliability of my system. www.relexsoftware.com Seymour Morris of Quanterion also gives a good 3 day course on reliability. smor...@quanterion.com The Relex software is pretty good, it will produce a report and calculate reliability of a system or even down to the sub-assembly level. The software has a library of failure rates for components that is okay, I found the best way was to contact the manufacturer of each component and request the FIT rate (failures in time) for each component and then I would plug those values into the software. I hope this helps. Regards, Brad Segarini -----Original Message----- From: Brian McAuliffe [mailto:bally...@iolfree.ie] Sent: Wednesday, September 19, 2001 4:09 AM To: NEBS Subject: Reliability predictions: SR-332 Hi 1. SR-332 (issued in May 2001) refers to the terms "device, "unit" and "serial system". Can anybody give examples of each ? 2. Is there anywhere in existence an idiots guide to performing reliability predictions as per the requirements of this document? 3. Presumably these predictions are best performed with the aid of a software tool. Can anybody give pointers to such tools - commercial, shareware, freeware ? As SR-332 is a recent issue, maybe 2. and 3. above do not exist. Do they exist for TR-332 Issue 6 ?? thanks in advance Brian McAuliffe MCA Compliance Consulting 13 Silver Grove, Ennis, Co.Clare, Ireland Tel: +353.65.6823452 Mobile: +353.87.2352554 Email: i...@mcac.ie