Can help you on question 2) The L10 figure is indeed often used by fan manufacturers and does specify the statistical time after which 10% of the fans will have failed. It is an expression for components whose failure rate is dependant on time of service, i.e. they have a non constant failure rate. MTBF figures are only appropriate for components that have a constant, time independent failure rate. To calculate and predict time dependant failure rates, you need to use a Weibull equation and require the correct shape and scale parameters for the component in question. Getting these out of manufacturers can be difficult. But with on of the three, shape, scale or L10, you can calculate the others.
For question 1) Covering redundancy and equipment availability in a complex system, a SEMI standard E10-0701 has been issued to cover this. However I am still waiting for my copy to arrive so have not been able to read it yet. Andrew Carson - Senior Compliance Engineer, Xyratex, UK Phone: +44 (0)23 9249 6855 Fax: +44 (0)23 9249 6014 -----Original Message----- From: Gary McInturff [mailto:[email protected]] Sent: 19 February 2002 15:52 To: [email protected]; [email protected] Subject: RE: Bellcore Redundancy Requirements? I'd be interested as well, for two reasons. 1) I think the requirement is a bit out of date, and really only discusses bringing in two DC power feeds, A and B. That however seems more adapted to the days of simpler systems that would take the power through some steering diodes and take it straight to a back plane and power all of the cards in the box. As things have become more complex systems inject system power supplies (DC-DC for example) into the network but the standards don't seem to address the need for redundancy at this point. Unfortunately, I don't have the document in my hands, it was a question that came up during some recent testing. 2) Isn't L-10 a fan type of specification. The point at which 10% of the fans fail. I have been chasing this question on and off for awhile. Thanks Gary -----Original Message----- From: [email protected] [mailto:[email protected]] Sent: Saturday, February 16, 2002 7:25 AM To: [email protected] Subject: RE: Bellcore Redundancy Requirements? Hello All, If any members of this forum have any response copies that were sent out to John's question below, would you please forward a copy to me? Thanks In Advance, Kaz Gawrzyjal [email protected] -----Original Message----- From: Kretsch, John [mailto:[email protected]] Sent: Wednesday, February 14, 2001 12:37 PM To: '[email protected]' Subject: Bellcore Redundancy Requirements? Does anyone in the collective know about _where_ Bellcore spells out any sort of redundancy requirements. There is a buzz about "L-10" requirements and I'm not sure where this comes from. TIA. Regards, John Kretsch ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: [email protected] Michael Garretson: [email protected] For policy questions, send mail to: Richard Nute: [email protected] ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list" ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list" ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
