Re: Examples of EMC problems in the real world
I was thinking more about radiated emission (30 Mhz-1 GHz) that is enhanced by cables. For some interesting results reported by Douglas Smith (cir. 1999 ) see: http://emcesd.com/tt120199.htm Effectively it is half (?) a turn if a ferrite clamp-cores are used, hence a distributed :-) Tim Foo, E-mail: f...@np.edu.sg ECE, School of Engineering, http://www.np.edu.sg/ece/ Tel: + 65 460 6143 Ngee Ann Polytechnic, Fax: + 65 467 1730 535 Clementi Road, Singapore 599489 "Ralph Cameron" To: "Wan Juang Foo" Sent by: cc: owner-emc-pstc@majordom Subject: Re: Examples of EMC problems in the real world o.ieee.org 06/28/01 09:01 PM Please respond to "Ralph Cameron" When the material of the core and the windings are as specified , the emission reduction is uniform over the range for which it is designed- 1Mhz-30Mhz. Resonance is avoided by a distributed winding Ralph Cameron - Original Message - From: "Wan Juang Foo" To: "Ralph Cameron" Cc: Sent: Thursday, June 28, 2001 1:45 AM Subject: Re: Examples of EMC problems in the real world > > The so call reduction in emmission does not happen all the time. There is > still the possibility of resonance, this I have observed in several cases > over the past 7 years . > > Tim Foo, E-mail: f...@np.edu.sg > ECE, School of Engineering, > http://www.np.edu.sg/ece/ Tel: + 65 460 6143 > Ngee Ann Polytechnic, Fax: + 65 467 1730 > 535 Clementi Road, > Singapore 599489 > > > > "Ralph Cameron" >To: > Sent by: cc: , (bcc: Wan Juang > owner-emc-pstc@majordom Foo/ece/staff/npnet) > o.ieee.org Subject: Re: Examples of EMC problems in the real world > > > 06/27/01 09:16 PM > Please respond to > "Ralph Cameron" > > > > > > > > Bob: > > It just occurred to me that list members may not be failimiar with the > application of these components after manufacture. If needed I would be > glad > to elaborate. Basically, since conducted immunity also decreases conducted > emissions its a double benefit. > > > > > --- 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 Healddavehe...@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,"
Re: Examples of EMC problems in the real world
When the material of the core and the windings are as specified , the emission reduction is uniform over the range for which it is designed- 1Mhz-30Mhz. Resonance is avoided by a distributed winding Ralph Cameron - Original Message - From: "Wan Juang Foo" To: "Ralph Cameron" Cc: Sent: Thursday, June 28, 2001 1:45 AM Subject: Re: Examples of EMC problems in the real world > > The so call reduction in emmission does not happen all the time. There is > still the possibility of resonance, this I have observed in several cases > over the past 7 years . > > Tim Foo, E-mail: f...@np.edu.sg > ECE, School of Engineering, > http://www.np.edu.sg/ece/ Tel: + 65 460 6143 > Ngee Ann Polytechnic, Fax: + 65 467 1730 > 535 Clementi Road, > Singapore 599489 > > > > "Ralph Cameron" >To: > Sent by: cc: , (bcc: Wan Juang > owner-emc-pstc@majordomFoo/ece/staff/npnet) > o.ieee.org Subject: Re: Examples of EMC problems in the real world > > > 06/27/01 09:16 PM > Please respond to > "Ralph Cameron" > > > > > > > > Bob: > > It just occurred to me that list members may not be failimiar with the > application of these components after manufacture. If needed I would be > glad > to elaborate. Basically, since conducted immunity also decreases conducted > emissions its a double benefit. > > > > > > --- 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 Healddavehe...@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,"
Re: Examples of EMC problems in the real world
The so call reduction in emmission does not happen all the time. There is still the possibility of resonance, this I have observed in several cases over the past 7 years . Tim Foo, E-mail: f...@np.edu.sg ECE, School of Engineering, http://www.np.edu.sg/ece/ Tel: + 65 460 6143 Ngee Ann Polytechnic, Fax: + 65 467 1730 535 Clementi Road, Singapore 599489 "Ralph Cameron" To: Sent by: cc: , (bcc: Wan Juang owner-emc-pstc@majordomFoo/ece/staff/npnet) o.ieee.org Subject: Re: Examples of EMC problems in the real world 06/27/01 09:16 PM Please respond to "Ralph Cameron" Bob: It just occurred to me that list members may not be failimiar with the application of these components after manufacture. If needed I would be glad to elaborate. Basically, since conducted immunity also decreases conducted emissions its a double benefit. --- 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 Healddavehe...@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,"
Re: Examples of EMC problems in the real world
Bob: It just occurred to me that list members may not be failimiar with the application of these components after manufacture. If needed I would be glad to elaborate. Basically, since conducted immunity also decreases conducted emissions its a double benefit. regards Ralph Cameron EMC Consulting and Suppression of Consumer Electronics (After sale) - Original Message - From: To: "Ralph Cameron" Cc: Sent: Wednesday, June 27, 2001 6:51 AM Subject: Re: Examples of EMC problems in the real world > > Ralph, what is a toroidal cord? Is it a power cord with toroids? > > Bob Heller > 3M Product Safety, 76-1-01 > St. Paul, MN 55107-1208 > Tel: 651- 778-6336 > Fax: 651-778-6252 > > --- 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 Healddavehe...@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,"
Re: Examples of EMC problems in the real world
Bob, I wish it were then I wouldn't have to wind it. No my eyesight is getting poor and I mean toroidal ( ring / donut shaped ) core. of powdered iron material. Ralph - Original Message - From: To: "Ralph Cameron" Cc: Sent: Wednesday, June 27, 2001 6:51 AM Subject: Re: Examples of EMC problems in the real world > > Ralph, what is a toroidal cord? Is it a power cord with toroids? > > Bob Heller > 3M Product Safety, 76-1-01 > St. Paul, MN 55107-1208 > Tel: 651- 778-6336 > Fax: 651-778-6252 > > --- 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 Healddavehe...@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,"
Re: Examples of EMC problems in the real world
Ralph, what is a toroidal cord? Is it a power cord with toroids? Bob Heller 3M Product Safety, 76-1-01 St. Paul, MN 55107-1208 Tel: 651- 778-6336 Fax: 651-778-6252 --- 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 Healddavehe...@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,"
Re: Examples of EMC problems in the real world
Ed: I use toroidal cores on anmost everything and they work by reducing the conducted common mode RF on the poweline to the equipment, the cable to VCrs or TVs or telephones ext. Toroid cores are nonn intrusive, void no warranties, do not compromise safety and may be removed an retruned to the owner when they're no longer needed. They are the perfect after sale for improving conducted immunity of electronic equipment. So to answer your quesrion, I'm talking about preventing the energy from entering the conducted port of the victim equipment. How we define sonducted port may differ from the common notion that the energytravels on the sheath of coax cable and if its not inhibited in some way it gets onto chassis ground and then its too late. I use the term isolate the DUT from the energy but do it with passive means. BTW if we all understand that acronym, I've been using the same technique successfully in most cases ( >95%) for 25 years. Its an ideal after sale solution which has been ignored. Ralph - Original Message - From: "Price, Ed" To: "EMC-PSTC (E-mail)" Sent: Tuesday, June 26, 2001 8:20 PM Subject: RE: Examples of EMC problems in the real world > > >-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. > > SNIP > > Ralph: > > When you describe the success of eliminating the "conducted component", are > you talking about preventing the energy from exiting the source equipment or > preventing the energy from entering the conducted port of the victim > equipment? > > If it's the former, then you are also reducing the radiated component (which > radiates from the common powerlines). > > BTW, I have a 1 MB zip file with plots of the RF field strength that I > measured at a number of the San Francisco BART stations. I'll email the > package to anyone who would like a copy (email me directly, not through the > list). The strongest field strengths were less than 10 V/M, and all > originated from personal communication devices. > > Regards, > > Ed > > Ed Price > ed.pr...@cubic.com > Electromagnetic Compatibility Lab > Cubic Defense Systems > San Diego, CA USA > 858-505-2780 (Voice) > 858-505-1583 (Fax) > Military & Avionics EMC Services Is Our Specialty > Shake-Bake-Shock - Metrology - Reliability Analysis > > --- > This message is from the IEEE EMC Society
RE: Examples of EMC problems in the real world
>-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. SNIP Ralph: When you describe the success of eliminating the "conducted component", are you talking about preventing the energy from exiting the source equipment or preventing the energy from entering the conducted port of the victim equipment? If it's the former, then you are also reducing the radiated component (which radiates from the common powerlines). BTW, I have a 1 MB zip file with plots of the RF field strength that I measured at a number of the San Francisco BART stations. I'll email the package to anyone who would like a copy (email me directly, not through the list). The strongest field strengths were less than 10 V/M, and all originated from personal communication devices. Regards, Ed Ed Price ed.pr...@cubic.com Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA USA 858-505-2780 (Voice) 858-505-1583 (Fax) Military & Avionics EMC Services Is Our Specialty Shake-Bake-Shock - Metrology - Reliability Analysis --- 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 Healddavehe...@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,"
RE: Examples of EMC problems in the real world
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) mod
