Re: SIL Ratings
Dear Dan You are correct, an IEC 61508 SIL is a property of an overall safety-related function or system. It cannot be applied to a constituent part. However, IEC 61508 gives you a list of the things that you need to provide safety-related systems designers with, so that they can decide how to use your product to achieve the IEC 61508 SIL they require. These include data on the product's : a) Quantified failure probability b) Hardware fault tolerance c) The techniques that you used to avoid and control systematic faults (in both hardware and software, not forgetting EMC) d) To what degree your product or its components have been ‘proved-in-use’ Note: SIL ratings are defined in IEC 61508 and this is probably what your customer was asking about - but the acronym SIL could possibly be used by other standards or guides, so you should check that IEC 61508's SILs is what they were really interested in. All the very best! Keith Armstrong www.cherryclough.com In a message dated 04/05/02 13:56:46 GMT Daylight Time, dan.kin...@heapg.com writes: Subj:SIL Ratings Date:04/05/02 13:56:46 GMT Daylight Time From:A HREF=mailto:dan.kin...@heapg.com;dan.kin...@heapg.com/A To:A HREF=mailto:emc-p...@majordomo.ieee.org;emc-p...@majordomo.ieee.org/A Sent from the Internet A customer called this week and asked what our SIL rating is on one of our products (Programmable Logic Controller). I had never heard of a SIL rating. I went to the web and discovered SIL stands for Safety Integrity Level and is addressed in IEC61508. My impression, from the web search, is that a SIL analysis would be accomplished on a large manufacturing process and the outcome would be based on the attributes of all of the components of the process, i.e.. sensors, controllers, output devices. I haven't seen anything on the web that indicates the individual components have a SIL rating. Does anyone have any experience with either SIL ratings or IEC61508 who might be able to shed some light? Dan Kinney Lead Qualification Engineer Horner APG, LLC Indianapolis, IN
SIL Ratings
A customer called this week and asked what our SIL rating is on one of our products (Programmable Logic Controller). I had never heard of a SIL rating. I went to the web and discovered SIL stands for Safety Integrity Level and is addressed in IEC61508. My impression, from the web search, is that a SIL analysis would be accomplished on a large manufacturing process and the outcome would be based on the attributes of all of the components of the process, i.e.. sensors, controllers, output devices. I haven't seen anything on the web that indicates the individual components have a SIL rating. Does anyone have any experience with either SIL ratings or IEC61508 who might be able to shed some light? Dan Kinney Lead Qualification Engineer Horner APG, LLC Indianapolis, IN --- 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org 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
RE: Stun Guns on Aircraft.
Actually, I understand that those devices that shoot darts are called Tasers, while stun guns have two metallic probes with about 20 kV across them when the trigger is pushed. Typically they are used in direct contact with the aggressor, so there would not be any live wires or darts bouncing around inside of the aircraft. I agree with Scott in terms of holes in the aircraft skin. There presently is a controlled leak, usually in the rear of the aircraft, which controls the pressure inside. If there were some bullet holes in the skin, the controlled leak would just adjust to leak less. However, a window would be another story, but it would not be as dramatic as shown in most movies. The windows are plastic so probably would not completely blow out, but it would make a lot of noise. John Shinn, P.E. (also a pilot) -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of sco...@world.std.com Sent: Friday, May 03, 2002 1:56 PM To: Gregg Kervill Cc: emc-p...@majordomo.ieee.org Subject: Re: Stun Guns on Aircraft. Gregg, I believe the type of device they are talking about is the kind that shoots a projectile with two electrodes that penetrate the skin. Thin wires remain attached to the gun and deliver shock pulses to the cockpit invader. I think that aircraft instrumentation has enough immunity to withstand emissions from the wires. The main trouble with this gadget (most of them are one shot deals) is if the bad guy was smart enough to bring friends. As for bullets, aircraft pressurization systems are designed with excess capacity. Even a couple of dozen bullet holes are very minor leaks for such a system. There would be a problem if a bullet damaged something but large aircraft have redundant systems for almost everything. Also, they would almost certainly only use pre- fragmented safety rounds. These are made up of very small birdshot stuck together and are designed to disintegrate on impact. I think by now it should be obvious which one I would want the pilot to have if I were one of the passengers. Scott Lacey On 3 May 2002 at 12:38, Gregg Kervill wrote: There have been several reports here (in the US) that airlines are placing guns or stun-guns on aircraft. I understand the risk of a bullet - I understand that the risk can be reduced by using a flat, disc-shaped, rubber projectile. BUT, the though of ANYONE discharging a stun gun on a flight deck full of mission critical (and sometimes not well buffered) electronics scares me more that the though of a terrorist. Please can someone tell me that I should not worry - or to stop flying. Best regards Gregg --- 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc
Re: Stun Guns on Aircraft.
Gregg, it's bad enough being in Reliability getting on a plane without thinking of the probability of failure, how old the parts are, is there enough redundancy, number of failure free trips etc. etc. etc. Please, let's not go there ... grin Reissue those special air marshall pistols from when they used to carry pistols on planes and put a couple of undercover air marshalls on the plane. Anyway, I'm not sure what kind of stun gun they're talking about - stun guns that are tasers which shoot two metal darts attached by wire to a charge source or the stun guns which have two metal prongs permanently attached to the device which you have to stab at the attacker. In any event both, if accidentally contacted equipment in a cockpit, would cause massive contact currents to circulate across the equipment. I don't think cockpit equipment is put through that much immunity testing. Regards, Doug McKean --- 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org 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
RE: Stun Guns on Aircraft.
...at least not North American trains, whose technology and infrastructure has fallen embarrassingly far behind that of much of the rest of the world. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: lisa_cef...@mksinst.com [mailto:lisa_cef...@mksinst.com] Sent: May 3, 2002 1:38 PM To: Fred Townsend Cc: emc-p...@majordomo.ieee.org; Gregg Kervill; owner-emc-p...@majordomo.ieee.org Subject: Re: Stun Guns on Aircraft. Well, I'd debate comparing lightning to a stun gun... one is on the outside, and one on the inside. Lightning has a bit more of a barrier to overcome than say 3,000 Volts to an instrument panel. I'm with Gregg... Hadn't really thought of it, but now that I have, give them the guns! Gregg, it's bad enough being in Reliability getting on a plane without thinking of the probability of failure, how old the parts are, is there enough redundancy, number of failure free trips etc. etc. etc. I think you've just put the last nail in the coffin ; - ) .and trains aren't building too much confidence these days either . Lisa --- 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org 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
