What Every Startup Needs to Know About NEBS
FYI, I just had an article published in Evaluation Engineering magazine titled: What Every Startup Needs to Know About NEBS. You can view it at: http://www.evaluationengineering.com/archive/articles/0502emc.htm http://www.evaluationengineering.com/archive/articles/0502emc.htm The article details the steps we took at General Bandwidth to pass NEBS testing our first time out. There's a pretty good resource section at the end that's not in the print copy. I hope the group finds it useful. Best regards, Dave Lorusso Director of Product Integrity General Bandwidth, Inc. 12303 Technology Blvd. Austin, TX 78727 512-681-5480 (phone) 512-681-5481 (fax) dave.loru...@genband.com mailto:dave.loru...@genband.com www.genband.com http://www.genband.com/
Re: SIL Ratings
See also my posting on 21 Dec 2001, giving a link to the IEC FAQ: http://www.iec.ch/61508/ EXTRACT: What is meant by a SILn system, subsystem or component? A safety integrity level (SIL) is not the property of a system, subsystem or component. However, the above phrase is often used to denote that the system, subsystem or component is capable of providing safety functions with a safety integrity level up to n. [end of quote] It is indeed appropriate to evaluate the safety function(s) of a PLC (or other electronic sub-assembly of a safety-related system) to determine their SIL rating. This facilitates their selection and integration into a complete safety system. Of course, a standard PLC is not suitable for a safety application. To achieve the SIL rating you need to meet specific requirements for failure rate, architecture, and (most especially) diagnostic coverage. In practice, a safety PLC will almost certainly be either dual- or triple-redundant. Also, IEC 61508 takes a life-cycle approach, so it is supposed to be considered at the design stage of the PLC. (If you have good design and production control processes, you may be able to assess compliance retrospectively.) You may also be interested in an FAQ that I wrote a while back. [Disclaimer: has a small amount of commercial content.] http://www.tuvasi.com/faq-fs.htm See http://www.tuv-fs.com/plclist.htm for some certified examples. [Disclaimer: This is on a website operated jointly by two test agencies]. As to what standard your enquirer referred to, the answer probably depends on the industry and the region: -IEC 61508 is international and generic (all industries). Published in 7 parts, total 700 pages approx. -ANSI/ISA-84.01-1996 Application of Safety Instrumented Systems for the Process Industries is for the (USA/Canada) PROCESS industry. It was published in 1996 when IEC 61508 was still at draft stage. -EN 61508 is identical to IEC 61508 -A process-industry-specific functional-safety standard is at draft stage, IEC 61511 -A machinery-industry-specific functional-safety standard is at draft stage, IEC 62061 (The sector-specific standards will apply the relevant principles and methods of IEC 61508 to a specific industry.) -Some other key differences: -ANSI/ISA S84.01 uses only three SIL levels (SIL 1 to 3) -IEC 61508 uses all four SIL levels (1 to 4) -S84.01 does not address the complete product life-cycle, from design to decommissioning, IEC 61508 does. -For a complete analysis, see clause 12 of S84.01. (Clause 12 was written in 1996, hence is somewhat out-of-date.) Per ISA: This standard [S84.01] is process industry specific within the framework of the International Electrotechnical Commission (IEC) draft Publication 1508. There are significant differences in S84.01 from IEC draft Publication 1508-1995, as described in Clause 12. However, IEC draft Publication 1508 was still being developed at the time that S84.01 was published. As a result, ISA SP84 will continue to support and monitor IEC draft Publication 1508 development, and will modify S84.01 as needed when IEC draft Publication 1508 is published. Per IEC: The standard [IEC 61508] is generic and can be used directly by industry (as a 'standalone' standard) and also by international standards organisations as a basis for the development of sector standards (e.g. for the machinery sector, for the process sector or for the nuclear sector). The standard will therefore influence the development of electrical, electronic and programmable electronic (E/E/PE) safety-related systems across all sectors. best regards, glyn -- TUV Rheinland of North America, Inc. Product Safety Quality Industrial Machinery Division (Chicago Office) Glyn R. Garside Senior Engineer 1945 Techny Rd, Unit 4 NORTHBROOK, IL 60062-5357, USA Tel (847)562-9888 ext 25 email ggars...@us.tuv.com http://www.us.tuv.com Dan Kinney (A) dan.kin...@heapg.comTo: 'emc-p...@majordomo.ieee.org' emc-p...@majordomo.ieee.org Sent by: cc: owner-emc-pstc@majordom Subject: SIL Ratings o.ieee.org
Re: Thermal Testing
richwo...@tycoint.com wrote: Do any of you monitor and record component temperatures during safety testing using PCs and data capture I/O cards? If so, what hardware and software to you use? I do any monitoring any temp testing with a Fluke Hydra II and associated PC software. Set up and define probes, start software, dump into an Excel spreadsheet or report. Communication between the Fluke and the PC is done through serial ports. - 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.
I hate to pull rank here but I doubt if any of you have designed cock pit equipment, tested it, or done a FAA flight certification submittal. I have. Let me reply, below, to points made by Jeff and Gregg. Collins, Jeffrey wrote: Group, I happened to be flying on United Airlines this weekend and thought I'd run this topic by a few pilots. (I got a chance to speak with 4 pilots separately) The consensus from the UA pilots was: * The stun guns have been thoroughly tested in the cockpit and had no effect on the avionics systems. * Type of stun guns( Taser only) would be the type that shoot the electrode through the air at the target. * They all preferred hand guns with bullets over the Tasers. They all claim that tests have been done unloading several rounds of bullets into the fuselage of an aircraft at critical altitudes without having severe affects. I am in total agreement. High Voltage guns, whatever you call them, deliver a high voltage at a very low current. I have not tested with Tasers but I have done ESD. Tasers are roughly equivalent to an ESD test. ESD Tests showed occasional minor damage to microphones, particularly those mounted on the wall to the side of the pilot or the autopilot might disengage if the yoke were zapped. Pilots are trained for autopilot disengagement. Redundancy was tested in many ways. One was to shoot virtual bullets at equipment. Virtual paths were selected at random. All equipment in the path was suddenly turned off by tripping the breakers. No single virtual bullet ever effected the flyability of the airplane. Two bullets on opposite sides of airplane could be troublesome but probably not fatal. All tests were conducted using simulation on the ground. L The field of my survey was small and only targeted a single airline so I don't know how this would correlate across the entire pilots union. Just thought I'd share this piece of info for what its worth. Regards, Jeff Collins IGregg Kervill wrote: Dear All, Many thanks for your comments - I think it may be worth making some comments in summary: 1- Lightning has the same effect. Disagree - lightening is an external effect - Physics 101 and the Ice Pail experiment. If anyone doubts the difference go and visit the Munich Science Museum where every day (I think they still do it) a volunteer climbs into a metal 'pod' and is winched between two electrodes (about 20 feet apart) and becomes part of the discharge path. Seeing it sure beat reading about it at school. Any discharge on the inside of the Ice Pail is transferred 'instantaneously to the outside surface - this is, after all, the principle upon which the Van de Graff(sp?P generator is based. (Note the volunteer does NOT wave out of the window!!!) You are partially correct. Lightning is a much bigger problem. The E field is external to the airplane. The B field enters the airplane and penetrates most shielding and therefore is internal. Stun guns are mostly a E field problem. The Ice Pail shows immunity to E fields. The same is true of the cockpit equipment. It is almost perfectly contained within ice pails called ATR boxes. The same protection is afforded to stun guns. ATR boxes usually do not protect against B fields making lightning the bigger problem. Because lightning is not a question of IF, but rather of WHEN, and because lightning is bigger problem, equipment is designed to survive lightning. 2- Holes in structure versus hole and carriers in semiconductor substrates (yes it was a pun). I agree with those who preferred the idea of perforated eardrums (depressurization) to perforated electronics. 3- Dead Pilot versus Dead Electronics. Neither is ideal - but many (most) commercial aircraft are fly be wire - One of my clients make Simulators - and I flew (for the first time ever) and Air Bus (simulator) from London Heathrow to London Gatwick - Landed (ON THE RUNWAY) and taxied (the most difficult part) to the airport. I had full control of the simulator and was flying by instruments. The controls are ALL electronic and if there had been multiple (i.e. non-random) fails then even a pilot would not have been able to move the control surfaces. I'm not sure what your point is here. Air Buses use fiber optics for most flight critical systems. 4- Testing - at 50kV? any comments from ESD engineers out there? My tests only went to 25KV. I think it largely a matter of current which is determined by the size of the storage capacitor, more than the voltage. 5- TASER versus Stun gun - thanks for correcting my misunderstanding - Two comments - First - if the stun gun is discharged through the airframe there will be an induced potential in local electronic systems. Correction. There will be an induced current. The potential will be almost zero across the very low resistance of airframe. Second - if I must turn off my tape
stun guns on aircraft
and other safety considerations keep the hijackers off planes using ground security an airplane in flight is not the place to have gun fights too many lives are at risk the first priority is to get the plane safely on the ground, anywhere then at least the passengers have a chance Most citizens of most countries enjoy the security that comes from having thrashed out land rights, territorial disputes, and the systems of law and law enforcement before firearms were invented. America is one of the few places in the West that relies on firearms as a negotiating tool. This is poor judgement. Firearms are offensive weapons not negotiating tools. Giving someone a gun escalates an already dangerous situation. Now you want the pilot to not only assure the safety of the plane but also be an effective executioner. Asking too much IMHO. Unfortunately America was taken by force and is defended by force and is unlikely ever to change. --- 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: Be set last
-- Virus Warning Message (on gemini2) Found virus WORM_KLEZ.H in file SK The file is deleted. If you have questions, contact virus-ad...@ieee.org - Thank you! 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 - summary and comments GK
Regarding the perforation of the aircraft by bullets, and the supposed gradual depressurization that should occur, it might be worth remembering the disaster of the world's first fleet of jet passenger aircraft, the British Comet. In the early 1950s they were falling out of the sky in some numbers. Very inconvenient. This was some 5 years before Boeing came out with its 707. Stress cracking caused a single, small window (about the same size as normal side windows) that the plane had on the top of the cabin, to begin to weaken. At some point the window began to crack and then suddenly gave way. The result was that nearly the entire contents of the cabin were explosively sucked through the open window. It took years to understand what had happened since all they could find was plane wreckage (usually under water) with bodies and seats scattered over an improbably large area. The result is that until the problem was found some years later, and corrected, the aircraft was taken out of service. It was this that allowed Boeing with its 707 (and shortly later, Douglas with its DC8) to catch up and dominate the market at the time. Suggesting that the only problem with bullet holes is that the pressurization system couldn't keep up with the air leakage, is therefore rather simplistic. The real problem is what happens when a window is hit and the pressure differential takes over causing explosive decompression. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Gregg Kervill [mailto:gkerv...@pgtv.net] Sent: May 6, 2002 9:42 AM To: emc-p...@majordomo.ieee.org Subject: RE: Stun Guns on Aircraft - summary and comments GK Dear All, Many thanks for your comments - I think it may be worth making some comments in summary: 1- Lightning has the same effect. Disagree - lightening is an external effect - Physics 101 and the Ice Pail experiment. If anyone doubts the difference go and visit the Munich Science Museum where every day (I think they still do it) a volunteer climbs into a metal 'pod' and is winched between two electrodes (about 20 feet apart) and becomes part of the discharge path. Seeing it sure beat reading about it at school. Any discharge on the inside of the Ice Pail is transferred 'instantaneously to the outside surface - this is, after all, the principle upon which the Van de Graff(sp?P generator is based. (Note the volunteer does NOT wave out of the window!!!) 2- Holes in structure versus hole and carriers in semiconductor substrates (yes it was a pun). I agree with those who preferred the idea of perforated eardrums (depressurization) to perforated electronics. 3- Dead Pilot versus Dead Electronics. Neither is ideal - but many (most) commercial aircraft are fly be wire - One of my clients make Simulators - and I flew (for the first time ever) and Air Bus (simulator) from London Heathrow to London Gatwick - Landed (ON THE RUNWAY) and taxied (the most difficult part) to the airport. I had full control of the simulator and was flying by instruments. The controls are ALL electronic and if there had been multiple (i.e. non-random) fails then even a pilot would not have been able to move the control surfaces. 4- Testing - at 50kV? any comments from ESD engineers out there? 5- TASER versus Stun gun - thanks for correcting my misunderstanding - Two comments - First - if the stun gun is discharged through the airframe there will be an induced potential in local electronic systems. Second - if I must turn off my tape recorder (powered but a single AA cell) because it may affect systems then how is discharging 50k considered to be safe and OK??? 6- Design of interfaces to cope - some of the prototype systems that I did safety and reliability work on in (1995)uses surface mount components to provide lightening protection - these devices would not provide Creepage distances of more than a couple of millimeters. 7- Ground computers - I agree that this is worrying - the UK has even more out of date equipment and then the new system (that will control air traffic in the South of England) used equipment (and software) purchased in the late 80's early 90's. I just hope that it still works when they take it out of the box. The point is that RANDOM failures exist and there procedures have been developed (and practiced) to deal with them. Anything that induces non-random and multiple failures is - I suggest - another ball game. 8- The chances are low - I agree - I was flying back from the west coast the morning of 9-11 and I did not get a warm fuzzy feeling about probability when I watched the news footage - but I have made many flights since and it will not stop me from flying. I am grateful for the fact that Europe and the middle East are sharing their security experiences with the US. Security is a cultural thing and the US has a long way to go before it provides the same level of security from officials AND MORE IMPORTANTLY from
Be set last
-- Virus Warning Message (on gemini2) SK is removed from here because it contains a virus. -
RE: Stun Guns on Aircraft.
Relax. The worst would be a modern Windows-based system that must be rebooted after the 'blue-screens' and 'general protection faults'. David -Original Message- From: Fred Townsend [mailto:f...@poasana.com] Sent: Friday, May 03, 2002 2:24 PM To: Gregg Kervill Cc: emc-p...@majordomo.ieee.org Subject: Re: Stun Guns on Aircraft. Do you think the EMI from a stun gun can compare to the airplane being hit by lightning? World wide, airplanes are hit by lightning every day. They don't crash. Relax If you want something to worry about... worry about the FAA flight tracking computers that were built the 1970s that fail every day somewhere across the USA. Be very worried. Fred Townsend 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 mailing list
