Conformity Magazine - February 2009 - (Page 20)

Appropriate QC activities are required for maintenance, repair, refurbishment, modification and firmware upgrades to ensure that the required EM and physical characteristics are not compromised over the vehicle lifecycle. Vehicle service schedules might need to include certain checks, tests or component replacements. EMC checks or tests might also need to be devised, and equipment provided for use by relatively unskilled technicians in dealers’ service departments for use at scheduled intervals. Computerized diagnostic programs might need to be modified to detect certain EM or physical characteristics. Repair instructions should include activities that maintain the vehicle’s EM/physical characteristics, possibly followed by EM and physical verification to specification. User manuals should recommend activities that help maintain the required EM/physical characteristics over the vehicle’s lifecycle, and may need to describe, in layman’s terms, how the user can identify EMI as the cause of a problem, and perhaps how to deal with it (in some circumstances). Documentation – the Safety Case To help manage functional safety, and for a good defense in case of a legal challenge, a safety case should be created that documents all the activities described above and shows how they achieve tolerable safety risks over the vehicle’s lifecycle. The Amount of Work Required Depends on the Level of Risk The greater the excess safety risk is above the tolerable level of risk (making increased risk-reduction necessary), the more critical the need that all of the activities described above are more detailed, comprehensive and in-depth, and that they are performed by people who are more knowledgeable and more competent in the necessary techniques. Conclusions This article has described a dozen reasons why it is generally not possible to rely solely on EM testing to help achieve tolerable functional safety risks. We have also shown that rare and untested EMI events that could cause a safety incident only once during a 10-year vehicle life could expose drivers to safety risks comparable with those of the world’s most dangerous occupations. These safety risks are most unlikely to be detected by a car dealer, even when a customer complains about the symptoms. EMI must be treated like any other possible cause of hazards, including malfunctions in firmware [35]. Appropriate techniques in assessing the EM/physical environments, and in design, verification and validation, manufacture, maintenance, repair, modification and upgrade are required to ensure that tolerable safety risks are achieved over the vehicle’s anticipated operational lifecycle. Keith Armstrong is a principal with Cherry Clough Consultants (www.cherryclough.com) and a frequent contributor to Conformity. He can be reached at keith. armstrong@cherryclough.com. The author would like to extend his thanks to functional safety expert John Cryer of the UK’s Health and Safety Executive, and automotive industry experts Steve Offer of Robert Bosch Australia, and James Gordon-Colebrook of 3C Test, Silverstone, UK, for their invaluable assistance. This article is based on a paper presented at the 2008 IEEE EMC Symposium. A longer version of the original IEEE paper was published by the Automotive DesignLine Newsletter in two parts in September 2008. Visit www.automotivedesign-europe.com and search by “EMC.” References 1. D A Townsend et al, “Breaking All the Rules: Challenging the Engineering and Regulatory Precepts of Electromagnetic Compatibility,” 1995 IEEE International EMC Symposium, Atlanta, pp 194 – 199. 2004/104/EC, the “Automotive EMC Directive,” Official Journal of the European Union, L 337/13 – L 337/58, November 13, 2004. Keith Armstrong, “New Guidance on EMC-Related Functional Safety,” 2001 IEEE International EMC Symposium, Montreal, August 13-17, 2001, ISBN 0-78036569-0/01, pp. 774-779. Keith Armstrong, “New Guidance on EMC and Safety for Machinery,” 2002 IEEE International. EMC Symposium, Minneapolis, August 19-23, 2002, ISBN: 0-7803-7264-6, pp. 680-685. Keith Armstrong, “Review of Progress with EMC-Related Functional Safety,” 2003 IEEE EMC Symposium, Boston, August 18-22, 2003, ISBN 0-7803-7835-0, pp 454-460. Automotive EMC Laboratory Recognition Program (AEMCLRP), www.conformity.com/2631. IEC TS 61000-1-2, basic safety publication, draft second edition, 77/356/DTS February 2008, “Electromagnetic Compatibility (EMC) – Part 1-2: General – Methodology for the achievement of the functional safety of electrical and electronic equipment with regard to electromagnetic phenomena.” IEC 61508, basic safety publication, “Functional Safety of Electrical/Electronic/Programmable Electronic SafetyRelated Systems,” (seven parts). IET guide on “EMC for Functional Safety,” August 2008, www.conformity.com/2632. 2. 3. 4. 5. 6. 7. 8. 9. FAST Link www.conformity.com/2630 20 Conformity february 2009 http://www.cherryclough.com http://www.automotivedesign-europe.com http://www.conformity.com/2631 http://www.conformity.com/2632 http://www.conformity.com/2630

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Conformity Magazine - February 2009 Contents Editor's Note FCC Clarifies Closed Captioning Requirements for DTV Receivers Commission Cracks Down (For the Fifth Time!) On Junk Fax Marketer FDA Requests Comments on Global Harmonization Documents Australia Now Requires Solar Panel Testing and Certification EU Drafting New Directive on Toy Safety EU Commission Revises Standards List for EMC, R&TTE Directives Additional Standards Published For the EU's Medical Devices Directive EU Commission Publishes Additional Standards for Directives on Active Implantable, In Vitro Medical Devices EMC For the Functional Safety of Automobiles ESD Open Forum The ILAC Arrangement: Facilitating Trade Efficient Methodology for the EMI Analysis of Optical Transceivers Including PCBs and/or Flex Circuits The EuP Directive - Implementation, Design Requirements and Issues Chambers, Shielding, and Accessories Buyer's Guide CPSIA Lead Requirements Apply to Existing Inventory, Says CPSC CPSC Clarifies Certifcation Requirements Other CPSC Actions in the News IEC Standards Update Product Reviews UL standards Update Telcordia Standards Update From Our "You Can't Make This Stuff Up" Department Looking Back: Items from Past Issues of Conformity Advertisers

Conformity Magazine - February 2009

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