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
