Re: odd immunity problems ?
15 yrs ago, I tested some gaming equipment. There were some unique test specs, including those to emulate catle prods. One of the specs was around 35kV with some strange C and R value equivalents. They (gaming mfgs) are very aware of the neccessity for hard equipment. Hans
Re: odd immunity problems ?
Lisa: Come to think of it, I have never seen a slot machine that wasn't encased in metal. Wonder if they use EMI gaskets?. Mike Conn Owner/Principal Consultant Mikon Consulting
Japan EMC/Safety Requirements
Group, What is your opinion / experience with Laboratory Test equipment entering the Japanese market? We certify our equipment to CE EN55011 EN50082-1 for EMC and UL3101 IEC 61010 for product safety. Does this type of equipment require VCCI, Dentori, or some other Japanese known agency marks?? Regards, Jeff Collins Perkin-Elmer Applied Biosystems EMC/Product Safety Engineer colli...@perkin-elmer.com
Re: Odd immunity problems.
Thanks Chris! I love the gas flame one! (pity its not EMC) Expect to see these in print one day. Keith Chris Dupres wrote: Hi Keith. As we wander round this world of Electro-fizz, pop and 2dB-over-limit, we come across all sorts of strange EMC behaviour, some directly witnessed, some without an actual source (I heard of a friend of the wife of the chap who reads the gas meters - etc.) A few more amusing ones have slippped into Urban Legend, or latterday Folklore, some are much more recent. 1. There is the story of the lady on the ninth floor of a block of flats who whenever she heated her milk for her bedtime drink, twenty seconds later there was a loud 'Donk' noise from the wall. Subsequent investigation showed that whenever the ladies Microwave was started, the lift was called from the ground floor and stopped at the ninth. The ladies kitchen was against the lift shaft and the noise was that of the lift doors closing. - Unattributed 2. There is the story of the short-term car park gates at Gatwick airport being opened simply by holding an electronic cigarette lighter up to the exit card reader, and flicking it a few times. This was discovered by careful TV surveillance, and the surveillance technician using his lighter to see the time! Indirectly attributable to the BAA. 3. A metal detector on a coffee packaging plant dumping 50 lbs of instant coffee into the scrap-sack whenever a CelNet phone was used within 20 metres. Witnessed by Chris Duprés. 4. A Tissot Two-Timer digital/analogue wrist watch which went into time travel mode (about x 60 )whenever a particular Motorola Micro-Tac portable phone nearby had someone actually speaking into the mouthpiece. Witnessed by Chris Duprés. It was my damn watch! 5. Motor Vehicles with Capacitor Discharge ignition systems stranded, unable to run, parked on the A5 at Clifton-on-Dusmore, near Rugby, UK. The fact that this road goes right through the middle of the NATO 16kHz transmitter may have been significant. ( Is this EMC, or just total overload?) Attributable to an AA patrol in The Halfway House Inn, Crick, Northants, UK. 6. And there is the one where the flame on the gas cooker flared up red and then went out whenever the phone rang... This was found to be due to the telephone extension bell up the garden being fitted to the gas supply pipe, such that whenever the bell rang the rust was shaken off the inside of the pipe which got carried through to the flame causing the flare up and then blockage. OK, this is not EMC per se, but it seemed funny anyway. This was culled from a UK magazine, probably Readers Digest, while waiting for the Dentist. 7. Lot's of other examples at home, including: - The TV changing channels or turning off whenever the central heating came on. - The TV presenting us with the Gatwick Airport Meteorology transmissions, albeit at very low level, when the Microwave was running. (we are about 2 miles from Gatwick). - A Ceramic firing kiln in the garage going up 10 degrees whenever a switchmode battery charger was running in the garage. - The outside Quartz Halogen security light comes on whenever my office lights (fluorescent) or the bathroom ventilation fan are switched off. There must be many, many weirder and funnier ones out there :-) Regards, Chris Dupres Surrey, UK.
re: odd immunity problems ?
Just curious, Anyone have insight on the immunity of Slot machines?? They must have some pretty rigid design criteria else we'd all be rich. Haven't heard of any odd immunity things happening at Vegas -- Or do people choose not to say? Lisa
Odd Immunity Problems
Since you brought it up, I am reminded of a time in my youth before the Hey Good Buddy... craze hit the CB world. Back when it was a serious citizens band, licenses were required and I was young and foolish. I had a 5 channel 1 watt Johnson Messenger One CB. Had great fun 'til I bought a one kW linear amplifier for it. Was talking to someone several states away (hundreds of miles) when a knock came at the door upstairs. Heard my neighbor from across the street screaming at my mother. My voice was coming through their stereo speakers even though the power was off! That wasn't the worst part, he heard me talking about spending time with their daughter, whom I was forbidden to see! Sure had no clue what EMI was then but, boy, did I ever learn about angry fathers! Today I am a Compliance Engineer, but did not marry his daughter. Regards, Scott s_doug...@ecrm.com
Reliability Engineering
Does anyone know if there is a Reliability Engineering group similar to this EMC/Safety group currently on the internet where engineering issues, ideas and experiances are discussed. Thankyou for your time. Tony Reynolds Compliance Enginnering Pitney Bowes.
EU Implementation date for IEC61326-1
I read an article saying IEC61326 will become an EN standard for EMC for Laboratory Equipment. What is the mandatory date for this to replace En50081-1/EN55011 and EN50082-1 that we have been using? Any other information related the 61326 would be helpful. Thanks, Tom Becker Compliance Engineer EGG Instruments
CSA and standards for electrical eq.
You could begin by reviewing CSA's website www.csa.ca You did not say what kind of equipments you had in mind. The standards will depend on the nature of the product. If you mean ITE products, the UL/CSA bi-national standards are almost identical to IEC 950 or EN 60950. Please respond to Paolo italpont%tin...@interlock.lexmark.com To: emc-pstc%ieee@interlock.lexmark.com cc:(bcc: George Alspaugh/Lex/Lexmark) bcc: George Alspaugh/Lex/Lexmark Subject: CSA and standards for electrical eq. Florence (italy), 7 july '98 Dear Sirs, do anyone know I can find informations/standards about CSA (canada) electrical safety requirements for equipments? Thank in advance. -- ing paolo fini italponti telecomunicazioni via Reims 12 50126 -Firenze ( Italy - UE ) italp...@tin.it --
Re: CSA and standards for electrical eq.
Hello Paolo, You can find the CSA's web-link and hundreds more on the Safety Link at: http://www.safetylink.com Regards, Art Michael * * * * * * * * * * * * * * * * * * * * * * * International Product Safety News * *Check out our current offer on the * * Safety Link at http://www.safetylink.com * * * * * * * * * * * * * * * * * * * * * * * On Tue, 7 Jul 1998, Paolo wrote: Florence (italy), 7 july '98 Dear Sirs, do anyone know I can find informations/standards about CSA (canada) electrical safety requirements for equipments? Thank in advance. -- ing paolo fini italponti telecomunicazioni via Reims 12 50126 -Firenze ( Italy - UE ) italp...@tin.it --
re: Reliability Engineering
And, the Reliability Engineering issues are DESCRIBED on any web sites? Thanks. - Original Text From: Tony Reynolds reyno...@pb.com, on 7/7/98 1:23 PM: Does anyone know if there is a Reliability Engineering group similar to this EMC/Safety group currently on the internet where engineering issues, ideas and experiances are discussed. Thankyou for your time. Tony Reynolds Compliance Enginnering Pitney Bowes.
Re: Odd immunity problems.
--- On Tue, 7 Jul 1998 09:24:45 -0400 geor...@lexmark.com wrote: Chris's list of rumored and witnessed interference problems points out several key points still true today. There are NO interference or immunity requirements for most of the world's electrical apparatus. I once heard the following. Before the present sophisticated PC games and such, there were the simple ping pong games that could be played by attaching a device to the inputs of a TV set. In some cases the user did not remove the antenna leads. Hence, the ping pong game signals would radiate up the antenna and show up on the screens of neighboring TV sets. Or leak across an A/B coax switch, hence the requirement for minimum isolation of an RF switch. I also heard that it was devices like this that brought about the FCC emission regulations for digital devices operating at 10kHz or above. Remember that this was before the PC explosion after 1981 or so. I remember the old Sega arcade video machines. They were constructed of wood or fiberboard, and had their functional modules distributed in various places throughout the non-conductive cabinet. Open circuit boards were nailed wherever it was convenient, there was a total rats-nest of point to point wiring, data and power wires were strung a couple of feet long without a thought to coupling, and there was no filtering. Machine to machine variation was huge. It was a time of buccaneer construction practices! It was this type of product, as well as the burst of TRS-80's, Apple II's and PET's, that really got the regulatory wave moving. BTW, when did the first Pong games hit the lounge scene. I seem to recall a console Pong machine in a Cupertino bar circa late 1975. Ed -- Ed Price ed.pr...@cubic.com Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA. USA 619-505-2780 List-Post: emc-pstc@listserv.ieee.org Date: 07/07/98 Time: 09:46:46 --
Re: Odd immunity problems.
H, could this be a universal EMC truth? --- On Tue, 7 Jul 1998 01:52:56 -0400 Chris Dupres chris_dup...@compuserve.com wrote: Hi Keith. As we wander round this world of Electro-fizz, pop and 2dB-over-limit, we come across all sorts of strange EMC behaviour - The outside Quartz Halogen security light comes on whenever my office lights (fluorescent) or the bathroom ventilation fan are switched off. I have a security floodlamp system for my backyard, equipped with a thermal motion sensor. I have found that I have a reliable, though unintentional, remote control capability simply by flicking the kitchen range vent fan on and off a couple of times. I told my wife that it's a special purpose, hard-wired, digital controller. Ed -- Ed Price ed.pr...@cubic.com Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA. USA 619-505-2780 List-Post: emc-pstc@listserv.ieee.org Date: 07/07/98 Time: 09:24:27 --
Re: Ce versus FCC
Obviously it is not the logic circuits I am refering to! The front end of the power supply has many types of scenarios that can cause high (30 MHz) frequency emissions. To name a few. Switcher pulse risetime and fall-off. As semiconductors get better adn smaller, their ft also better (to other tham EMC folks!), Rectifier diode turn-on time (same story, better, cheaper, faster), resonant circuits (unintentional ones), resonant heatsinks (yes, I've had this one) and more. Granted, they are not common everyday occurances, but they occur. Hans
CSA and standards for electrical eq.
Florence (italy), 7 july '98 Dear Sirs, do anyone know I can find informations/standards about CSA (canada) electrical safety requirements for equipments? Thank in advance. -- ing paolo fini italponti telecomunicazioni via Reims 12 50126 -Firenze ( Italy - UE ) italp...@tin.it --
EMC Design Seminars
Chris Kendall will be presenting the CORE EMC Design I and CORE EMC Design II seminars: Brea, California (Southern California) - July 13-15, 1998 Fremont, California (Northern California) - August 3-5, 1998 For more information, contact me directly or visit the CKC Web site. Todd Robinson Marketing Manager CKC Laboratories, Inc. E-mail: trobin...@ckc.com Web: http://www.ckc.com Toll Free: (800) 500-4EMC
Re: EFT on ISA cards
In a message dated 98-07-07 02:31:48 EDT, treph...@macconnect.com writes: Testing AC lines will prove whether your card can withstand whatever EFT can pass through the power supply filtering, but just as important,EFT is as much a radiated immunity test as it is a conducted test. Often I/O cables and others act as pickup antennas, and you should consider the possibility of your AC cord acting like a transmit antenna. Tom Cokenias Consultant, EMC Radio Type Approvals I echo the sentiments in this reply: not all power supplies are created equal. You can take the stance to design for the worst power supply you find installed, or you can take a risk and design to the best. I know what I would do.. Derek Walton Owner L F Research EMC Design and Test Facility
Re: Odd immunity problems.
Yes, Chris. Quite amusing. Then, of course, there's the famous fly in the microwave debate ... ducking quickly Chris Dupres wrote: Hi Keith. As we wander round this world of Electro-fizz, pop and 2dB-over-limit, we come across all sorts of strange EMC behaviour, some directly witnessed, some without an actual source (I heard of a friend of the wife of the chap who reads the gas meters - etc.) A few more amusing ones have slippped into Urban Legend, or latterday Folklore, some are much more recent. 1. There is the story of the lady on the ninth floor of a block of flats who whenever she heated her milk for her bedtime drink, twenty seconds later there was a loud 'Donk' noise from the wall. Subsequent investigation showed that whenever the ladies Microwave was started, the lift was called from the ground floor and stopped at the ninth. The ladies kitchen was against the lift shaft and the noise was that of the lift doors closing. - Unattributed 2. There is the story of the short-term car park gates at Gatwick airport being opened simply by holding an electronic cigarette lighter up to the exit card reader, and flicking it a few times. This was discovered by careful TV surveillance, and the surveillance technician using his lighter to see the time! Indirectly attributable to the BAA. 3. A metal detector on a coffee packaging plant dumping 50 lbs of instant coffee into the scrap-sack whenever a CelNet phone was used within 20 metres. Witnessed by Chris Duprés. 4. A Tissot Two-Timer digital/analogue wrist watch which went into time travel mode (about x 60 )whenever a particular Motorola Micro-Tac portable phone nearby had someone actually speaking into the mouthpiece. Witnessed by Chris Duprés. It was my damn watch! 5. Motor Vehicles with Capacitor Discharge ignition systems stranded, unable to run, parked on the A5 at Clifton-on-Dusmore, near Rugby, UK. The fact that this road goes right through the middle of the NATO 16kHz transmitter may have been significant. ( Is this EMC, or just total overload?) Attributable to an AA patrol in The Halfway House Inn, Crick, Northants, UK. 6. And there is the one where the flame on the gas cooker flared up red and then went out whenever the phone rang... This was found to be due to the telephone extension bell up the garden being fitted to the gas supply pipe, such that whenever the bell rang the rust was shaken off the inside of the pipe which got carried through to the flame causing the flare up and then blockage. OK, this is not EMC per se, but it seemed funny anyway. This was culled from a UK magazine, probably Readers Digest, while waiting for the Dentist. 7. Lot's of other examples at home, including: - The TV changing channels or turning off whenever the central heating came on. - The TV presenting us with the Gatwick Airport Meteorology transmissions, albeit at very low level, when the Microwave was running. (we are about 2 miles from Gatwick). - A Ceramic firing kiln in the garage going up 10 degrees whenever a switchmode battery charger was running in the garage. - The outside Quartz Halogen security light comes on whenever my office lights (fluorescent) or the bathroom ventilation fan are switched off. There must be many, many weirder and funnier ones out there :-) Regards, Chris Dupres Surrey, UK. -- __ Begin of Forwarded Material __ End of Forwarded Material The comments and opinions stated herein are mine alone, and do not reflect those of my employer.
Re: Ce versus FCC
In a message dated 98-07-06 20:40:33 EDT, rbus...@es.com writes: A test house explained to me that the FCC allows either CISPR or FCC limits/procedures providing that one can determine worst case. Consequently, you have to test both ways (120 V 60Hz or 230V 50Hz) to determine which way you should have tested. So, where are the time/money savings? RIck, I think it's good practice to explore your product somewhat before you go for compliance testing. It helps determine just what you need to quantify in the test lab, and what can be ignored. I have not yet met with problems going this route with any agency folks, in fact I would expect them to endorse it. Our lab makes its living helping folks make these decisions before they go to a DLS, Elite, UL etc where the charges are much higher, but the labs are certified. Derek Walton Owner L F Research EMC Design and Test Facility
RE: Ce versus FCC
Typically, the range switch on the cost-sensitive (cheap) power supplies changes the front-end topology from conventional capacitor input to a voltage -doubled one. Since the power load stays the same, the current will double. But the nature of the input current to these supplies is gulps of current rather than sinusoidal draw. At the higher voltage the conduction angle of the current pulse gets very narrow so the current spike grows even more in magnitude. This can take the cores into saturation and lead to low frequency (25-100 kHz) conducted emissions problems. The effect is related more to voltage than frequency. The logic-created frequencies are not afffected by the AC input voltage or frequency. -- From: Gary McInturff[SMTP:gmcintu...@packetengines.com] Reply To: Gary McInturff Sent: Monday, July 06, 1998 6:30 PM To: hmellb...@aol.com; dwight.hunnic...@vina-tech.com; emc-p...@ieee.org Cc: eric.lif...@natinst.com Subject: RE: Ce versus FCC That's interesting. The change from 50 to 60 Hz would change some input components and that could effect the input impedance and hence the conducted emissions signature but the voltage, especially if its a well regulated and filtered supply should be invisible. The components that radiate at that point are all of the secondary 5 or 3.3 volt oscillators and stuff. They shouldn't even know the difference in the input voltage. If using a switcher power supply it seems even more odd. The input voltage is rectified and then chopped to #$@ then more regulating and filtering stuff happens. Then it hits the electronics. Anybody else see this and have an idea why it might. I may be living in a fools paradise here. Gary McInturff Packet Engines -Original Message- From: hmellb...@aol.com [SMTP:hmellb...@aol.com] Sent: Monday, July 06, 1998 11:16 AM To: dwight.hunnic...@vina-tech.com; emc-p...@ieee.org Cc: eric.lif...@natinst.com Subject:Re: Ce versus FCC I have encountered certain European agencies requesting that not only are the conducted emissions required to be performed at 230V 50Hz but radiated emissions as well. I agree that for conducted emissions it may make a difference but I have not seen radiated emissions change when the power source is changed from 60 to 50 Hz (while keeping Voltage the same). I did, however, see recently a product change emissions when the voltage was changed from 120 to 230 V. And, it did not matter if it was 50 or 60 Hz, only the voltage was significant. Go figure! Hans
Odd immunity problems.
Chris's list of rumored and witnessed intereference problems points out several key points still true today. There are NO intereference or immunity requirements for most of the world's electrical apparatus. Perhaps the most famous case of intereference was when shipboard electronics fired a rocket from a fighter on the deck of a U.S. carrier. The resulting fire resulted in the loss of lives and millions of dollars in damage. As a result of this incident, and the density of typical shipboard electronics, the U.S. Navy is extremely sensitive to EMI/EMS issues. While the Army's blackhawk helicopters were falling from the skies due to simple AM/FM radio signals, the Navy's version of the same craft was very immune to these, as the EMI/EMS specs were far tighter than the Army's. I once heard the following. Before the present sophisticated PC games and such, there were the simple ping pong games that could be played by attaching a device to the inputs of a TV set. In some cases the user did not remove the antenna leads. Hence, the ping pong game signals would radiate up the antenna and show up on the screens of neighboring TV sets. I also heard that it was devices like this that brought about the FCC emission regulations for digital devices operating at 10kHz or above. Remember that this was before the PC explosion after 1981 or so. There is also the story of how something was causing havoc with the emergency services two way radio communications in Nevada, i.e police, fire, and ambulances. An exhaustive investigation led to one or more really noisy pin ball machines at a roadside pub. The owner was ordered to fix or get rid of them. He got rid of them and the problem went away. However, it soon reappeared, as another pub owner wound up with the same machines. Once a user has purchased an FCC Class B piece of equipment, it is his/her responsibility to correct interference problems that may still result. This is explained in the required FCC statement in manuals, listing several ways that might solve the problem. The reasoning is quite simple. The unit has proven to meet required emission limits. If intereference results, it means (1) the affected equipment has low immunity, (2) the two units are placed too close together, or (3) the existing FCC/CE limits are too lenient. Who wants even lower emission limits for ITE? Recall that the limits were established to protect wireless communications, e.g. radio, TV, public health and safety etc. They were not intended to protect every piece of electronic equipment on the market, much of which is designed with no regard to immunity. George Alspaugh Lexmark International
RE: Tantalum Capacitors
David- See also the technical report (available from AVX) Surge in Solid Tantalum Capacitors by John Gill of AVX. He discusses the surge failure mode of tantalum caps in low Z circuits (e.g. DC power supplies). Charlie __ Reply Separator _ Subject: Tantalum Capacitors Author: Brumbaugh, David [SMTP:david.brumba...@pss.boeing.com] at IMS List-Post: emc-pstc@listserv.ieee.org Date:6/30/98 11:46 AM Can anyone tell me if there are any drawbacks in using tantalum capacitors in dc power supply filters? My recollection is that they can pop if the voltage polarity is reversed, or if there are large negative voltage swings during transients. TIA, David Brumbaugh The BOEING Company Information, Space Defense Systems Electromagnetic Effects M/C 8H-11 POB 3999 Seattle, WA 98124-2499 Phone: Kent Space Center (253) 773-3733
RE: Ce versus FCC
Your comment below is absolutely true. Manufacturers spend far too much time and money obtaining certifications for so many countries that have just minor differences in their standards. One standard for EMC/product safety is too simple I guess. Darrell -- From: owner-emc-p...@majordomo.ieee.org To: emc-p...@ieee.org Cc: rbus...@es.com Subject: Ce versus FCC List-Post: emc-pstc@listserv.ieee.org Date: Monday, July 06, 1998 1:10PM A test house explained to me that the FCC allows either CISPR or FCC limits/procedures providing that one can determine worst case. Consequently, you have to test both ways (120 V 60Hz or 230V 50Hz) to determine which way you should have tested. So, where are the time/money savings? As a personal note, it seems to me that there will always be slight differences whether it be, test sites, cables, input power, placement, whatever. The objective should be to reduce levels to reasonable, repeatable limits. Defining an acceptable standard or test procedure should be adequate. We should not have to incur unnecessary testing just to address a few dB one way or the other. Rick
RE: NARTE Certifcation
NARTE can be reached at (508) 533-8333. For anyone interested in this certification, they will send an informative package detailing the requirements for certification and a list of study guides. For those of us who weren't smart enough to grandfather when that opportunity was given, the exam is the only way to become certified. The required experience for an engineer is 9 years and a technician is 5 years. Each year of college will count as a year of experience. There are no preparation courses for the NARTE exam that I'm aware of but, the study guide is useful to find out what type of material wil be on the exam. The study guide is entitled Study Guide for Electromagnetic Compatibility Engineers and is available through: The SCEEE Press Northeast Consortium for Engineering Education (NCEE) 1101 Massachusetts Avenue St. Cloud, FL 34769 The NARTE information package also lists other books which are useful to bring to the exam. +--+ | Mike Cantwell, PE| | Director of EngineeringRheinTexas, Inc. | | NARTE Certified EMC Engineer Suite 150 | | Tel: (972) 509-25661701 East Plano Pkwy | | Fax: (972) 509-0073Plano, TX 75074 | +--+
SV: Ce versus FCC
A fools paradise or not I don't know but to say that it is only secondary
circuits that radiates is not true. I have several switch mode power
supplies which have radiated emission up to 150MHz. Especially from 40 -
100MHz I often see problems. This emission is normally very sensitive to
the power consumption/input current. But you are right a step from 115 to
230 V don't make that big different but a change from 200 to 240 can. As
I see it, it is the current flow arround switch transistor - bridge -
transformer which are the main problems. Transistor and transformer is
normally not affected by 115/230 but what about the first bridge ? here
the current will change by a factor 2 ! or am I wrong ?
Best regards,
Mr. Kim Boll Jensen
ScanView, Denmark
--
Fra: gmcintu...@packetengines.com[SMTP:MIME @INTERNET
{gmcintu...@packetengines.com}]
Sendt: 7. juli 1998 04:05
Til: hmellb...@aol.com; dwight.hunnic...@vina-tech.com;
emc-p...@ieee.org
Cc: eric.lif...@natinst.com
Emne: RE: Ce versus FCC
--
--
That's interesting. The change from 50 to 60 Hz would change some input
components and that could effect the input impedance and hence the
conducted emissions signature but the voltage, especially if its a well
regulated and filtered supply should be invisible. The components that
radiate at that point are all of the secondary 5 or 3.3 volt oscillators
and stuff. They shouldn't even know the difference in the input voltage.
If using a switcher power supply it seems even more odd. The input
voltage is rectified and then chopped to #$@ then more regulating and
filtering stuff happens. Then it hits the electronics.
Anybody else see this and have an idea why it might. I may be living in
a fools paradise here.
Gary McInturff
Packet Engines
-Original Message-
From: hmellb...@aol.com [SMTP:hmellb...@aol.com]
Sent: Monday, July 06, 1998 11:16 AM
To: dwight.hunnic...@vina-tech.com; emc-p...@ieee.org
Cc: eric.lif...@natinst.com
Subject: Re: Ce versus FCC
I have encountered certain European agencies requesting that not
only are the
conducted emissions required to be performed at 230V 50Hz but
radiated
emissions as well. I agree that for conducted emissions it may
make a
difference but I have not seen radiated emissions change when
the power source
is changed from 60 to 50 Hz (while keeping Voltage the same). I
did, however,
see recently a product change emissions when the voltage was
changed from 120
to 230 V. And, it did not matter if it was 50 or 60 Hz, only the
voltage was
significant. Go figure!
Hans
Fil: ENVELOPE.TXT
EMC Workshop shipboard measurements
Dear collegues EMC Workshop held by Rohde Schwarz will take place on 14.-15.07.1998. in Split, Croatia, EMC lab of Marine Electronics Center. It is connected with shipboard measurements of RF EM fields originating from shipboard RF equipment. Measurements are conducted by EMC project at FER (Faculty of Electrical Engineering) in Zagreb, Croatia. Regards, Antonio Sarolic -- Antonio Sarolic FER Zagreb Dept. of Radiocommunications and Microwave Engineering Unska 3 HR-1 Zagreb CROATIA E-mail: antonio.saro...@fer.hr tel. +385 21 305 660 / fax. +385 21 563 877
Odd immunity problems.
Hi Keith. As we wander round this world of Electro-fizz, pop and 2dB-over-limit, we come across all sorts of strange EMC behaviour, some directly witnessed, some without an actual source (I heard of a friend of the wife of the chap who reads the gas meters - etc.) A few more amusing ones have slippped into Urban Legend, or latterday Folklore, some are much more recent. 1. There is the story of the lady on the ninth floor of a block of flats who whenever she heated her milk for her bedtime drink, twenty seconds later there was a loud 'Donk' noise from the wall. Subsequent investigation showed that whenever the ladies Microwave was started, the lift was called from the ground floor and stopped at the ninth. The ladies kitchen was against the lift shaft and the noise was that of the lift doors closing. - Unattributed 2. There is the story of the short-term car park gates at Gatwick airport being opened simply by holding an electronic cigarette lighter up to the exit card reader, and flicking it a few times. This was discovered by careful TV surveillance, and the surveillance technician using his lighter to see the time! Indirectly attributable to the BAA. 3. A metal detector on a coffee packaging plant dumping 50 lbs of instant coffee into the scrap-sack whenever a CelNet phone was used within 20 metres. Witnessed by Chris Duprés. 4. A Tissot Two-Timer digital/analogue wrist watch which went into time travel mode (about x 60 )whenever a particular Motorola Micro-Tac portable phone nearby had someone actually speaking into the mouthpiece. Witnessed by Chris Duprés. It was my damn watch! 5. Motor Vehicles with Capacitor Discharge ignition systems stranded, unable to run, parked on the A5 at Clifton-on-Dusmore, near Rugby, UK. The fact that this road goes right through the middle of the NATO 16kHz transmitter may have been significant. ( Is this EMC, or just total overload?) Attributable to an AA patrol in The Halfway House Inn, Crick, Northants, UK. 6. And there is the one where the flame on the gas cooker flared up red and then went out whenever the phone rang... This was found to be due to the telephone extension bell up the garden being fitted to the gas supply pipe, such that whenever the bell rang the rust was shaken off the inside of the pipe which got carried through to the flame causing the flare up and then blockage. OK, this is not EMC per se, but it seemed funny anyway. This was culled from a UK magazine, probably Readers Digest, while waiting for the Dentist. 7. Lot's of other examples at home, including: - The TV changing channels or turning off whenever the central heating came on. - The TV presenting us with the Gatwick Airport Meteorology transmissions, albeit at very low level, when the Microwave was running. (we are about 2 miles from Gatwick). - A Ceramic firing kiln in the garage going up 10 degrees whenever a switchmode battery charger was running in the garage. - The outside Quartz Halogen security light comes on whenever my office lights (fluorescent) or the bathroom ventilation fan are switched off. There must be many, many weirder and funnier ones out there :-) Regards, Chris Dupres Surrey, UK.
Re: EFT on ISA cards
Jeff, Testing AC lines will prove whether your card can withstand whatever EFT can pass through the power supply filtering, but just as important,EFT is as much a radiated immunity test as it is a conducted test. Often I/O cables and others act as pickup antennas, and you should consider the possibility of your AC cord acting like a transmit antenna. Tom Cokenias Consultant, EMC Radio Type Approvals
Re: EN61000-3-2 Harmonics testing 16 amps ITE equipment
On Mon, 6 Jul 1998 16:28:20 -0400 , you wrote: Perhaps the conflict of dates is in the source of the document. The IEC may say one date and the EU may adopt quite another. As an example: an EU parallel vote document is usually pretty much in sync with the IEC. IEC 60950 on the other hand was about 1 and a half years behind the IEC at one time. It is a lot better today. We must not confuse the IEC dates with the EU implementation dates. Someday I'll break the link in my brain between standards sources (IEC, CISPR, etc.) and the groups that use them (EU, other countries, etc.) Having said that the 50 W implementation date is 1999 for the IEC and would also have been for the EU except for subsequent EU amendments. The EU extended the dow until 2001 because of the extreme controversy surrounding the standard from many sources. The same is true for the flicker standard. My view is the 50 Watt implementation date is 1999 for home products and because of the 2001 date for most other products, the 50 Watts means nothing until 2001. The EU dates always govern the regulatory requirements. So, does this mean the 75W-50W reduction is 4 years later than the EU implementation of the spec - 1/1/2005? snip -- Patrick Lawler plaw...@west.net
Re: Ce versus FCC
good point, Gary. Only the front end of the switcher would see the different input voltage and frequency. The high-speed oscillators on the motherboards, etc., should not be affected by input voltage/frequency, yes? Dwight Gary McInturff wrote: That's interesting. The change from 50 to 60 Hz would change some input components and that could effect the input impedance and hence the conducted emissions signature but the voltage, especially if its a well regulated and filtered supply should be invisible. The components that radiate at that point are all of the secondary 5 or 3.3 volt oscillators and stuff. They shouldn't even know the difference in the input voltage. If using a switcher power supply it seems even more odd. The input voltage is rectified and then chopped to #$@ then more regulating and filtering stuff happens. Then it hits the electronics. Anybody else see this and have an idea why it might. I may be living in a fools paradise here. Gary McInturff Packet Engines -Original Message- From: hmellb...@aol.com [SMTP:hmellb...@aol.com] Sent: Monday, July 06, 1998 11:16 AM To: dwight.hunnic...@vina-tech.com; emc-p...@ieee.org Cc: eric.lif...@natinst.com Subject:Re: Ce versus FCC I have encountered certain European agencies requesting that not only are the conducted emissions required to be performed at 230V 50Hz but radiated emissions as well. I agree that for conducted emissions it may make a difference but I have not seen radiated emissions change when the power source is changed from 60 to 50 Hz (while keeping Voltage the same). I did, however, see recently a product change emissions when the voltage was changed from 120 to 230 V. And, it did not matter if it was 50 or 60 Hz, only the voltage was significant. Go figure! Hans -- DWIGHT HUNNICUTT Sr. Compliance Engineer * dwi...@vina-tech.com * * (510) 413-1349 direct * * (510) 492-0808 fax * * VINA Technologies,Inc. * * 42709 Lawrence Place* * Fremont, CA 94538 *
RE: Ce versus FCC
That's interesting. The change from 50 to 60 Hz would change some input components and that could effect the input impedance and hence the conducted emissions signature but the voltage, especially if its a well regulated and filtered supply should be invisible. The components that radiate at that point are all of the secondary 5 or 3.3 volt oscillators and stuff. They shouldn't even know the difference in the input voltage. If using a switcher power supply it seems even more odd. The input voltage is rectified and then chopped to #$@ then more regulating and filtering stuff happens. Then it hits the electronics. Anybody else see this and have an idea why it might. I may be living in a fools paradise here. Gary McInturff Packet Engines -Original Message- From: hmellb...@aol.com [SMTP:hmellb...@aol.com] Sent: Monday, July 06, 1998 11:16 AM To: dwight.hunnic...@vina-tech.com; emc-p...@ieee.org Cc: eric.lif...@natinst.com Subject:Re: Ce versus FCC I have encountered certain European agencies requesting that not only are the conducted emissions required to be performed at 230V 50Hz but radiated emissions as well. I agree that for conducted emissions it may make a difference but I have not seen radiated emissions change when the power source is changed from 60 to 50 Hz (while keeping Voltage the same). I did, however, see recently a product change emissions when the voltage was changed from 120 to 230 V. And, it did not matter if it was 50 or 60 Hz, only the voltage was significant. Go figure! Hans
Re: Ce versus FCC
Dwight, While pursuing a TCF route, this was discussed at length with our CB. The frequency was of secondary concern to the line voltage. We tested with both frequencies anyway because we can: it made no discernable difference to our emission or immunity data.. Best regards, Derek Walton Owner: L F Research EMC Design and Test Facility
