Conformity Magazine - July 2008 - (Page 50)

on by Tom Skopal, Acopian Power Components he highest reliability attainable in a single power supply is not nearly as good as that of a redundant power system, in which the outputs of two (or more) power supplies are connected so that – even if one were to fail – the other(s) would continue to provide uninterrupted power to the load. For illustration, if the mean time between failures (MTBF) of the power supplies were 100,000 hours and the mean time to repair (or replace) a supply were less than one hour, the MTBF of a twosupply redundant power system would theoretically approach the square of 100,000 hours – almost 150 years! And by using power supplies with a higher inherent reliability, or by including three or more supplies in a redundant power system, the MTBF could easily be extended even further. Of course, practical considerations (such as the drying of electrolytic capacitors) would require periodic refurbishment/ replacement of the individual power supplies. But, with thoughtful mechanical design, this can be done in seconds or minutes and not significantly affect the system MTBF. Therefore, a redundant power system should be used for any equipment where the highest possible reliability is essential, and an unexpected loss of power would be disastrous. Such applications include communications systems (both voice and data types), computer systems (volatile memory systems in particular), process controls, utility and municipal systems, and security/safety alarm systems. Some Considerations for Using Redundant Power Supplies T © Scott Maxwel | Dreamstime.co Maxwell Dreamstime.com 50 Conformity JULy 2008 http://Dreamstime.co

Table of Contents Feed for the Digital Edition of Conformity Magazine - July 2008

Conformity Magazine - July 2008 Contents Editor's Note FCC Adopts 6 Million Dollars in DTV Enforcement Orders Commission Enforcement Bureau Adopts V-Chip Consent Decree FDA Seeks 2 Million Dollars from Medical Device Manufacturer FDA Answers Questions About CFLs and UV Radiation EPA Issues Energy Star Specs for TV, Video Boxes Canada Unveils Sweeping Product Safety Legislation How the Evolution of CISPR Standards Continues to Shape the Requirements for Anechoic Chambers ESD Open Forum Reach Compliance for Non-EU Article Manufacturers The iNARTE Informer Preamplifier Considerations for Emission Measurement Systems Effective Shielding in Medical Electronics Applications Product News Focus On...Power Components Buyer's Guide Updated Standards List for the EU's ATEX Directive EOS/ESD Symposium Set for September CPSC Actions in the News Researchers Work to Develop Non-Flammable Batteries Safety Link Launches Redesigned, Enhanced Web Site IEC Standards Update UL Standards Update Product Reviews Telcordia Standards Update From Our "You Can't Make This Stuff Up" Department Looking Back: Items from Past Issues of Conformity Advertisers

Conformity Magazine - July 2008

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