Hey Gary, Check out "Banana Skins" in EMC Compliance Journal, too.
http://www.compliance-club.com/archive1/archindex.html Dave Wilson Senior Compliance Engineer Alidian Networks Inc. tel: (408) 273 4787 fax: (408) 273 4800 -----Original Message----- From: Gary McInturff [mailto:gary.mcintu...@worldwidepackets.com] Sent: Wednesday, June 20, 2001 2:12 PM To: EMC-PSTC (E-mail) Subject: Examples of EMC problems in the real world There have been requests in the past on this forum for examples of real world events that were EMC related, as I recall we got a few but not many examples. In an email with Ralph he mentioned some work and an article that he had written chronically some of these problems. I asked him for some of his examples and he kindly sent the items below and has graciously allowed me to forward them. Thanks Ralph, and I hope that you enjoy them as much as I did. Gary -----Original Message----- From: Ralph Cameron [mailto:ral...@igs.net] Sent: Tuesday, June 19, 2001 6:14 PM To: Gary McInturff Subject: Some life threatening cases of EMI and others Gary: These cases were reviewed in an article I wrote about 14-15 years ago. Most incidents could happen tomorrow and came from a record of emi cases reported to all Canadian district offices of what used to be called Communications Canada. The reports covered a planned three month monitoring period during which time ther were 439 emi related reports and another 242 cases of swamping ( RF overload of TV, radio etc.) If you consider that Canadian incidents represented about 8% of the total number of incidents in the U.S. at that time, it may help to place the occurrences in perspective. Since that time, Industry Canada has not recorded domestic problems or complaints due to a lack of immunity ( radiated or conducted) but do have an advisory bulletin specifying field strengths communication transmitter owners cannot exceed. These limits are taken from the EU requirements for electronic equipment radiated immunity . Not surprisingly, I have found at least 95% of interference cases have been resolved not by increasing radiated immunity but, by reducing or eliminating most of the conducted component That's why I believe the simple expedient of designed in conducted immunity levels the playing field for all consumers and removes the nuisance of trying to find a solution, particularly, after sale. Examples: London Ont. A vhf broadcast radio link , owned by a commercial broadcast station , operating in a shopping mall, disrupted electronic weigh scale operation. False and incorrect weights and prices were displayed while the link was operating. Peterborough Ont. A CAT scan medical device's operation was disrupted by transmissions from a new FM broadcast transmitter. Brampton ON Radio frequency plastic sealing equipment located in close proximity to a neighbouring paint operation seized control of the six foot paddles stirring the vat of paint to the point where the shaft broke away from the motor , burst through a water tank and embedded itself in the factory wall. Toronto ON A hospital heart monitoring system displayed erroneous readings when the hospital radio despatch system was operated. Toronto ON A Federal government's computer system would "crash" when a nearby chiropractor operated his diathermy ( radio frequency generator ) machine. Edmonton Ab The telephone company lost billing data from their computer system which was attributed to the operation of a nearby private commercial radio despatch system. Calgary Ab An amateur radio operator's transmissions were heard in the recording equipment of a professional recording studio. Until the problem was resolved, the studio lost money on their operations. Grande Prairie Ab When a hospital's diathermy was used, the hospitl alert system would occasionally issue a a 'code 9' alert, in error. The diathermy also affected the physiotherapist's treadmill by accelerating the motor control mechanism. Grande Prairie Ab The mobile cranes on a logging company's railway had a collision avoidance system installed in each crane. Radio transmissions would occasionally defeat the protection offered by these systems. In Ottawa ON Ontario Hydro Electric Power Commission reported that Oil fired generating stations' control equipment on oil fired generators was affected by operation of nearby mobile radio equipment . Gas monitors, required for confined space atmosphere, continuous monitoring of toxic/ explosive gases and oxygen were found to give false alarms in 7 of 8 tested near UHF , narrowband ( 466Mhz ) transmissions and one had problems from 49Mhz narrow band signals. Because many amateur radio operators reside in urban areas, their HF operations ( covering 1.8-144Mhz ) have been demonstrated to affect the following . In some instances they could cause harmful effects: Intravenous pump in hosptial room went into the reset ( fail safe) mode when a 2W(144Mhz) handy talky was operated any closer than six feet from the pump. A manual reset is necessary to continue pump function. Although this happened on 26 separate occasions and I reported it to our Federal Dept of Health, they had the manufacturer investigate the problem and couldn't duplicate it. VCR and kitchen mantle radios generate objectionable noise when NOT powered Output transistor junctions make good detectors when energy is power line conducted. Garage door openers operate intermittently due to presence of RF many Mhz removed from their intended frequency of operation. ( Remember Pres. Nixon's Air Force One setting of many west coast garage door openers every time he decided to vacation in his California ranch). Just last year, a commercial aircarft undergoing maintenance at an Air Canada hangar in Montreal was suspended from a crane while undergoing mechanical as well as radio maintenance. Upon installation of the SSB HF radio, the maintenance personnel operated the radio within the hangar to discover that the crane began to lift the aircraft without human intervention. Only a quick thinking oeprator prevented serious consequences. While not life threatening , but adding a aura of mystique, was one I personally investigated in a home located about 1/4 mile from a broadcast transmitter. It was a "talking " card table, caused by rectification in a rusty leg joint. After getting over the shock of that the homewoner commenced to tell me that that was nothing his neighbour " had a talking waterbed". Yes, thermostats can rectify. !! There are many more similar cases to the above and all involve radio sensitive equipment. Fifteen years ago, electronic test equipment manufacturers were designing immunity into their products as the ambient was estimated at one volt conducted and more than one volt radiated. I wonder what it is today?. Ralph Cameron EMC Consluting and Suppression of Consumer Electronic Equipment (After sale) ----- Original Message ----- From: "Gary McInturff" <gary.mcintu...@worldwidepackets.com> To: "'Ralph Cameron'" <ral...@igs.net> Sent: Tuesday, June 12, 2001 10:35 AM Subject: RE: Wireless Network Issues > Ralph, > Readers have in the past, requested examples of EMC problems, I > wonder if you could share some of your experiences you mention in the last > paragraph. > Gary > > -----Original Message----- > From: Ralph Cameron [mailto:ral...@igs.net] > Sent: Monday, June 11, 2001 8:11 PM > To: kyle_cr...@dell.com; emc-p...@majordomo.ieee.org > Subject: Re: Wireless Network Issues > > > > Kyle: > > Take a look at www.Intellon.com . They detail a link to some of the > problems associated with proximity of Bluetooth devices to 802.11 LAN > specs. These are claimed to be potential interference problems related to > hop frequency differences in the two spread spectrum systems. > > There is also concern with the power line conducted control systems and the> Continental Automated Building Associated attempted to address some of the > issues related to compatibility during their conference held at the end of > May. There are some 26 different standards all independantly developed > which I'm sure is enough for a statistical study of the problem. > > There have been several papers on lack of EMC in hospitals - some > originating from McGill University in Montreal. The main problem there seems > to be lack of any emc equipment requirements ( although changing due to > liability ) and the solution has been to isolate the areas containing the > radio sensitive equipment. > > Tha Radio Advisory Board of Canada's EMC sub committee did address some > concerns toward cable TV radiation and possible effects on some aircraft > frequencies. With those problems largely overcome by regulating the cable > operators , another issue has arisen and that could affect radio aids to > navigation and it may have to do with radiation from home wiring above 2Mhz > . This is conceivable with ever increasing data rates and unshielded wiring. > > When I was chairman of the RABC EMC committee for a couple of years, there > were many instances of life threatening incidences related to lack of EMC. > > > Ralph Cameron > Electromagnetic Compatibiliy Consulting and Suppression of Consumer > Electronics > ( after sale) > > > ----- Original Message ----- > From: <kyle_cr...@dell.com> > To: <emc-p...@majordomo.ieee.org> > Sent: Monday, June 11, 2001 5:23 PM > Subject: Wireless Network Issues > > > > > > Hi All, > > I am currently researching wireless intereference issues for a > > project and I was wondering if anyone could answer a few of my questions. > > First off, any links to information that deals directly with wireless > > interference on airplanes or in hospitals would be appreciated. Secondly, > I > > am curious how similar cell phone wireless technology is to wireless > network > > technology(Wi-FI), from an EMI standpoint. The reason I ask is that I can > > find a lot of information about cell phone intereference, but I have found > > nothing about wireless network interference. I am still learning a lot > > about this, so any information that you could provide would be > appreciated. > > > > Thanks, > > Kyle > > > > ------------------------------------------- > > 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: > > Michael Garretson: pstc_ad...@garretson.org > > Dave Heald davehe...@mediaone.net > > > > 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://www.rcic.com/ click on "Virtual Conference Hall," > > > > > > > ------------------------------------------- > 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: > Michael Garretson: pstc_ad...@garretson.org > Dave Heald davehe...@mediaone.net > > 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://www.rcic.com/ click on "Virtual Conference Hall," > ------------------------------------------- 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: Michael Garretson: pstc_ad...@garretson.org Dave Heald davehe...@mediaone.net 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://www.rcic.com/ click on "Virtual Conference Hall," ------------------------------------------- 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: Michael Garretson: pstc_ad...@garretson.org Dave Heald davehe...@mediaone.net 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://www.rcic.com/ click on "Virtual Conference Hall,"