Hi Brian:
> While our design technically conforms to the requirements of > 60950-1, I do > not feel 'right' about a single component bridging either > primary/secondary, or primary/floating metal in a Class II > unit until I > can learn more about Y1 cap reliability and typical failure > modes, so I > have no information for a case-by-case basis. Stress and reliability requirements for Y-capacitors are specified in IEC 60384-14 and UL 1414. If the capacitors are certified, these standards are quite good at getting reliable parts. Study the standards, and you may feel better about using a single Y1 cap. Y1 capacitors are rated for reinforced insulation, and can be used in Class II equipment between mains and accessible parts, including SELV. I've had no hesitation in using certified Y1 caps in such applications. And, I've had no failures of certified Y1 or Y2 caps. Since EMC requirements came into effect, virtually every product has employed certified Y1 or Y2 caps. This is a very good base for judging reliability. I'm not aware of any Y-cap field failure problems. For typical failure modes, contact your Y-cap manufacturer. Failure modes are likely unique to each manufacturer. If you are still concerned about reliability, and if cost is not an issue, use two Y caps in series. Y2 caps are rated for basic or supplementary insulation. Or, to be super-conservative, use two Y1 caps in series. Best regards, Rich - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
