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RE: Conducted emission testing for EN55022 - diode + caps
Gunter, I discuss this on pages 71-72 of my book, Electronic System Design: Interference and Noise Control Techniques, published by Prentice-Hall in 1987 (now out of print, but you might find a copy by searching for the ISBN number 0-13-252123-7). A50-250nFcapacitor across each rectifier usually works well. John Barnes Advisory Engineer Lexmark International (and soon to be Chief Engineer, dBi Corporation) gunter_j_maass%embraco.com...@interlock.lexmark.com on 01/24/2002 04:52:19 AM Please respond to gunter_j_maass%embraco.com...@interlock.lexmark.com To: CE-test - Ing. Gert Gremmen - ce-marking and more... cetest%cetest...@interlock.lexmark.com, emc-pstc%majordomo.ieee@interlock.lexmark.com cc:(bcc: John Barnes/Lex/Lexmark) Subject: RE: Conducted emission testing for EN55022 - diode + caps Hello Take care to bridge the rectifier diodes with capacitors, otherwize thay might create interference themselves. Does anybody have some material (papers, book references, etc) about using capacitors in parallel with the rectifier diodes (with use them, how to determine their capacitance, etc ) ? Thank you ! Günter J. Maass Researcher - Power Electronics Development EMBRACO S.A. --- 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: No longer online until our new server is brought online and the old messages are imported into the new server.
RE: Zero Crossing Question
John, Or another example where different companies' equivalent parts are not equivalent-- this is one that I ran into in 1977. I had designed a Power-On-Reset (POR) circuit using a 555 timer, and had tested the circuit on a solderless breadboard. I was being sneaky in my design, and used the RESET, TRIGGER, and THRESHOLD inputs as three separate inputs to the 555. When we built the first tester the POR circuit didn't work. I then discovered that there were two flavors of 555 timers-- TI's and most companies 555's obeyed TRIGGER if(TRIGGER 1/3*VCC) AND (THRESHOLD 2/3*VCC). But the National Semiconductor LM555, which we used when we built the tester, obeyed THRESHOLD instead... Since this is an undefined input state for the 555, the chip designers did as they pleased. I have heard of many other cases where engineers have used components outside the published specifications, and gotten burned for their trouble. Bob Pease has written several Pease Porridge columns in Electronic Design about specmanship, and about how Design Engineers and Applications Engineers at chip manufacturers *try* to write honest datasheets over the objections of the marketeers. His best advice was: 1. If in doubt, try it out. 2. If an unspecified characteristic is important to you, contact the manufacturer and get them to guarantee it in writing. You may find yourself having to retest your design every time the chip manufacturer does a die shrink or moves the chip to a different process or plant. But you are much better off to find this out early, and have time to find a suitable alternative part or make a lifetime buy of the older (working) part than to suddenly have 100% of your products fail in production. John Barnes Advisory Engineer Lexmark International (soon to be Chief Engineer, dBi Corporation) --- 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: No longer online until our new server is brought online and the old messages are imported into the new server.
RE: European and North American Cordage
Ron, On the first Network Attach product I helped develop, the IBM 4033 External Network Adapters, we wound up with 156 top bills-of-materials to cover three basic models (announced in 1991): * 4/16Mbps Token-Ring. * 10BASE-T/10BASE2 Ethernet. * 10BASE-T Ethernet). We had: * Two basic raw cards, with the Ethernet card being populated with/without the 10BASE2 components. times * Two sets of one-time-programmable (OTP) EPROM's, because the EPROM's were not big enough to hold both OS/2 and Netware code. times * Three power supplies-- a US/Canada single-output power supply, a worldwide dual-output power supply, and a Nordic dual-output power supply for Austria, Denmark, Finland, Norway, Sweden, and Switzerland because we could not get the worldwide power supply approved for these countries. times * Nine line cords. times * Five sets of documentation in English, French, German, Italian, and Spanish. This was a manufacturing nightmare, as you may imagine, just trying to keep all the different pieces in stock! Distribution was also a great pain, because we had to build units for specific markets and could not shuffle them to take care of excess demand in one country from excess inventory in another country. Customer service wasn't too happy with us either, because they had to keep six adapters and three power supplies in stock worldwide. Our next External Network Adapter, announced in 1993, was the Lexmark MarkNet XLe. We had two basic models, a 4/16Mbps Token-Ring unit and a 10BASE-T/10BASE2 unit, with two parallel ports. We had an optional serial port, making a total of four variants for the product. We included enough flash ROM on this unit to hold all the protocols that a customer would need (OS/2, Netware, unix's, etc.) (Scratch one set of EPROM's.) I again developed the power supply, this time a switcher operating from 90-256VAC 50-60Hz, and which we got approved for worldwide use. (Scratch two power supplies.) The power connector was an appliance input/output connector. We used a universal (HARSVT) jumper cord with an IEC 320-C13 shrouded male connector on one end and an IEC 320-C14 plug on the other end. We stole the linecord from a printer, and plugged it into the the appliance inlet. The jumper cord went from the appliance outlet on the MarkNet XLe to the printer's appliance input. (Scratch eight linecords.) The user documentation was in English, French, German, Italian, and Spanish, with technical documentation only in English. (Scratch four sets of documentation.) So, to sell four variants worldwide, we had only *four* top bills of material. We have used this same scheme on all of our External Network Adapters we have developed since 1993, and it has saved us a tremendous amount of grief in purchasing, manufacturing, distribution, and customer service. If you would like to see what kind of a mess you can get into for worldwide products, and how sweetly switcher power supplies and universal linecords can cover them, please take a look at Oscar Overton's and my webpage: ftp://ftp.lexmark.com/pub/networking/internat.htm THAT is why I like universal cordage. John Barnes Advisory Engineer Lexmark International --- 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: No longer online until our new server is brought online and the old messages are imported into the new server.
Re: European and North American Cordage
Peter, We used a HARSVT 3x18AWG 1.00mm2 Universal linecord from Feller on the Lexmark MarNet XLe External Network Adapter. This had a Harmonized plus UL/CSA-listed cordage. I can't find my Feller catalog right now, and their website (http://www.feller-at.com/ ) doesn't say, but I think that they had HARSVT cordage in 16AWG and 14AWG, along with HARSJT cordage. John Barnes Advisory Engineer Lexmark International --- 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: No longer online until our new server is brought online and the old messages are imported into the new server.
Designing Electronic Equipment for ESD Immunity-- Annotated Bibliography
A recent query on this forum asked about the relative effectiveness of capacitors versus diodes for Electrostatic Discharge (ESD) protection. These are just two of over 220 topics covered in my article, Designing Electronic Equipment for ESD Immunity, which I wrote for Printed Circuit Design magazine: * Part I athttp://www.pcdmag.com/story/OEG20010928S0122 (July 2001 issue). * Part II athttp://www.pcdmag.com/redux/0701_esd.html (posted on www.pcdmag.com in November 2001). I had hopes that the magazine would put the bibliography for the article on their website, so that it would be freely available to anyone who needed it. So far they haven't. But Lexmark has given me an opportunity (and some substantial incentives) to take a Pre-Retirement Leave of Absence, which is supposed to start in February. One of my projects, to keep myself active and out of trouble, is creating a website on Robust Electronic Design-- how to develop electronic equipment and electronic products that: 1. Work safely and reliably. 2. Can be manufactured economically. 3. May be marketed and used worldwide. 4. Can be easily adapted to meet new or unforeseen requirements. My web-hosting contract provides for plenty of disk space and for several gigabytes of data transfers each month under the basic rate. I've also added about 100 documents to my collection since I wrote the article. So I've put my current ESD bibliography on the website in three pieces: * http://www.r-e-d-inc.com/esd-anno.htm a partially annotated bibliography on ESD, covering nearly 1480 source documents (I work on this as I have time). * http://www.r-e-d-inc.com/esd-term.htm 220+ terms under which I found information on the subject, with the key words and key phrases I used in the annotated bibliography. * http://www.r-e-d-inc.com/esd-want.htm magazines, journals, and conference proceedings that have had one or more papers/articles on the subject. This last webpage is also my search list, listing documents that I have seen cited in the literature but so far have been unable to locate. I would appreciate any leads you may have as to libraries or personal collections from which I could get copies of these. Enjoy! John Barnes Advisory Engineer Lexmark International jrbar...@lexmark.com (work) jrbar...@iglou.com (home) --- 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: No longer online until our new server is brought online and the old messages are imported into the new server.
Designing Electronic Equipment for ESD Immunity
The second half of my article, Designing Electronic Equipment for ESD Immunity, has just been posted on Printed Circuit Design magazine's website. The full article is now available on line: * Part 1 athttp://www.pcdmag.com/story/OEG20010928S0122 * Part 2 athttp://www.pcdmag.com/redux/0701_esd.html We used quite a few of the techniques described in this article during the development of the Lexmark X820e MFP (Multi-Function Printer)-- see http://www.lexmark.com/US/Products/printers/0,2792,MjM4OXwx,00.html I designed the controller card (with a 100MHz 64-bit memory bus, 350MHz processor, and 1051 other components on a 12.5 x 7.9 6-layer card), which went into production on the second spin of the card. We have entered both my controller card, and our scanner card for the X820e, in Mentor Graphics' 2002 PCB Technology Leadership Awards design competition. I am scheduled to start a Pre-Retirement Leave of Absence from Lexmark in February 2002. One of the projects I have in mind, once I get away from working massive overtime designing controller cards, is to flesh this article out into a book. Enjoy! John Barnes Advisory Engineer Lexmark International --- 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: No longer online until our new server is brought online and the old messages are imported into the new server.
RE: Define Continuous DC Voltage
From my reading on the subject, EN 60950 has different Safety Extra-Low Voltage (SELV) limits for alternating current (AC) and direct current (DC) because the human body reacts to them differently. AC makes your muscles contract, so you tend to hang onto the source of the electric shock. DC makes you push away, removing contact, but you may fall or otherwise hurt yourself as you jerk away from the source of the shock. I have heard hams (amateur radio operators) tell of picking themselves off the floor, clear across the room, after accidently touching the plate supply of a tube radio. I found an article in Electronics magazine, published between 1940 and 1945 (I can't find the article right now), on a study that was done on let-go current. In this study the subjects (something like 100 young males) would grab a 1/4 wire with one hand, and put their other hand on a copper or brass plate. The experimenter would apply a voltage between the wire and the plate, giving the subject a shock. Then the subject would try to let go of the wire. If they couldn't, they could open the circuit just by lifting their hand from the plate. If the subject could let go of the wire, the experimenter would increase the voltage and they would try the experiment again. As I recall the experiments were done mainly at 50 and 60Hz, with some done at DC and low frequencies, and others up to 10kHz. The results of the study were that let-go current was lowest in the 40-100Hz range, and ranged from 15mA up to about 100mA. (I got the impression that some of the young men were trying to show how macho they were...) The let-go current increased as the frequency increased above 100Hz, or decreased below 40Hz. For DC the subjects had trouble trying to hold onto the wire, and instead of a shock they felt a heating effect. I have not seen any studies on how much AC superimposed on DC changes the let-go effect to a hang-on effect, and I don't plan to find out for myself if I don't have to... John Barnes Advisory Engineer Lexmark International --- 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: No longer online until our new server is brought online and the old messages are imported into the new server.
Re: FCC Class A and Class B testing
Cecil, With that low a price point for the Photo Color Printer, unless you have a completely weird interface you will not convince the FCC that it is an industrial-use-only device. Some consumers will want to buy it, so you will have to test to Class B. If you do a good job of designing the printer, there should be little or no cost difference between just meeting Class A and easily meeting Class B. You can expect to spend a little more time in the EMC chamber to meet Class B... If you have a 100BASE-Tx Ethernet or 16Mbps Token-Ring interface on the printer, you may have a struggle getting it down to Class B. If you have a choice of shielded or unshielded connectors, make provisions for installing shielded connectors and for tying them to chassis ground with a short wide connection: * Metal standoffs holding the connector face tight against the chassis-- parallel and serial ports. * Metal tab on the connector shield clamped to the chassis with a metal screw-- USB, IEEE 1394. * A strip of copper tape if you have no other options, but manufacturing folks hate this because they cut their fingers on the sharp edges of the tape. John Barnes Advisory Engineer Lexmark International --- 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: No longer online until our new server is brought online and the old messages are imported into the new server.
RE: 10/100 base interface in a plastic box
Gary, About 50% of our 100BASE-Tx cards require an additional 4-line common-mode choke between the transformer-filter and the RJ-45 connector, to meet Radiated Emissions limits with enough margin to satisfy our electromagnetic compatibility (EMC) folks. So we snuggle all three components as close together as our manufacturing guidlines will allow, usually within 0.025 of one another pad-to-pad or pad-to-body. Since the transformers and filters in the transformer-filter are symmetrical between the + and - sides, and the transmit and receive sides often are the same, we shuffle the pin numbers in the common-mode choke and transformer-filter so that the traces run almost parallel (no crossovers) in the critical area between the RJ-45 connector and the transformer filter: RJ-45 ++common- transformer- !!modefilter ! O !choke +--+ ! O! +--+ /-! ! ! O--! !--/ ! ! ! O! ! ! /-! ! ! O ! /-! !--/ ! ! ! O-/ ! ! ! ! ! O--! !--\ ! ! ! O-\ ! ! \-! ! !! \-! !--\ ! ! ++ +--+ \-! ! +--+ This forces vias and crossovers in the RXD+, RXD-, TXD+, and TXD- lines to the zone between the transformer-filter and the PHY or MAC/PHY, where they are much less critical. We also try to get the PHY or MAC/PHY as close as we can to the transformer-filter, no more than 1 inch away and preferable within 0.5 inch, with the trace lengths closely matched. Depending on how bold the engineer is, on our first engineering cards we will short the pads of the common-mode choke together with traces or with 0-ohm surface-mount resistors paralleling the windings of the common-mode choke. I personally prefer the resistors, because if we ever discover that we need the common-mode choke, all I have to do is no pop the four resistors and put the common-mode choke in their place. I've considered using a 0-ohm 4-resistor resistor network, but didn't feel comfortable with the coupling that might cause between the receive and transmit signals on pins 2 and 3. Since my most recent card had over 1000 components crammed onto a 12.5 x 7.9 card, including a 350MHz X86 processor, six large ball-grid array (BGA) parts, and provisions for 512MB of SDRAM, I wasn't willing to take any risks that I didn't have to. (We started production two months ago using the second spin of my card...) John Barnes Advisory Engineer Lexmark International --- 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: No longer online until our new server is brought online and the old messages are imported into the new server.
Re: 10/100 base interface in a plastic box
Jon, My department has developed ten generations of Ethernet adapters (10BASE2, 10BASE-T, 100BASE-Tx) for IBM/Lexmark printers since 1990. We have looked at, but so far have not used, integrated-magnetics connectors because we like having the option of putting a common-mode choke in between the Ethernet magnetics (transformer-filter) and the connector. In our card layouts we: 1. Define a FRAME_GROUND to connect the metal bodies/shields of all connectors going to the outside world. 2. Connect FRAME_GROUND to GROUND with 4-or-more ground ties, 0.025-inch wide traces on the topside and bottomside of the card. We use at least one pair of ground ties for every 3 inches of beach front with connectors going to the outside world. 3. For the Ethernet interfaces, put a void in all layers stretching from the center of the transformer-filter to the farthest pins of the RJ-45 connector, 0.2 wider than the transformer-filter, common-mode choke, and RJ-45 connectors. The *only* wires permitted in this area are the Ethernet transmit/receive signals. 4. Run FRAME_GROUND down the edge of the card, as wide as we can make it, ending in mounting pads for a metal bracket or the chassis. These pads have non-plated-through holes for the mounting screws circled by eight vias, and are plated with tin or tin-lead on the topside and bottomside. FRAME_GROUND has the same outline in all copper layers, although we sometimes have to leave it as a void in ground planes because of a quirk in Mentor Graphics.Put a via about every 1/2 inch along FRAME_GROUND to connect the layers together. 5. Place a ground tie at each mounting pad topside and bottomside, with additional topside and bottomside ground ties roughly equally spaced in between the mounting pads. During development testing, these groundties can be easily cut with an X-acto knife if it looks like separating FRAME_GROUND from GROUND, or having them connected at only one end, might improve radiated emissions and electrostatic discharge (ESD) immunity. Make sure that solder does not get onto the mounting pads during manufacturing. The mounting pads sit right on the lugs of the metal bracket/chassis. These contact points on the metal bracket/chassis must be bare metal. We recently discovered that a transparent phosphate wash applied to a chassis before powder coating, as a priming step, seriously affected radiated emissions and the ESD immunity. We now require these contact points to be masked off before the chassis goes through any cleaning/painting steps. A machine screw with a built-in belleville washer, and a nut with a captive star washer, hold the card and the metal bracket/chassis in tight metal-to-metal contact despite temperature changes, vibration, creeping of the plating, etc. For our External Network Adapters, the metal bracket is bent into L, and extends all the way under the card. This bracket ties the faces of metal connectors together, connects to FRAME_GROUND, and provides a ground plane all the way under the card to reduce radiated emissions and reduce our susceptibility to tabletop ESD (an IBM test). From the side the card, connectors, and bracket look like this: ! !+--+ !! ! !! ! ! + ! -- insulating spacer, or tab bent up to support card + here-- experiment to see whether having the card and bracket isolated or connected gives the best EMC/ESD results John Barnes Advisory Engineer Lexmark International --- 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: No longer online until our new server is brought online and the old messages are imported into the new server.
Re: ESD Design, non-earthed products
Alex, I have written an article for Printed Circuit Design magazine on Designing Electronic Equipment for ESD Immunity. Part 1 appeared on pages 18-26 of the July 2001 issue (volume 18 number 7), and Part 2 will be in the August issue. Printers and copiers can be quite nasty generators of ESD, with the moving paper acting like the belt of a Van de Graaf generator to generate voltages of thousands of volts. One defense is to use tinsel or static-discharger brushes to bleed charge off the paper (rule L4 in my article) as it leaves the printhead area. Dogpile ( http://www.dogpile.com ) searches for antistatic +tinsel, static +tinsel, static +brush*, and antistatic +brush* gave these hits, for example: * http://www.westmontinc.com/price.htm * http://www.fraser-antistatic.co.uk/products.htm * http://www.takk.com/takktins.htm * http://kinetronics.com/ * http://www.stopstatic.com/printer.html * http://www.chapman-static.com/oemtinsel.html * http://www.amstat.com/html/passive.html Another technique is to make plastic parts in the paper path of antistatic materials, and make sure that every shaft has a grounding contact (usually on one end of the shaft) to bleed off charge (rule L3). An alternative to the grounding contact is to use conductive grease in the bearings (rule L5). Establishing a chassis ground for any ungrounded device is difficult. About the best you can do is choose a large piece of metal close to the switches/operating controls, and tie circuit common, shields, and grounding wires from the mechanism to it (rule B14). John Barnes Advisory Engineer Lexmark International --- 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: Detachable AC Cordset Selection for the EU
Paul, I can't cite the exact clauses, because another engineer has borrowed all my product safety standards, but UL 1950 has a deviation that calls for the primary plug of a device to be rated for 125% of the device's rated input current. UL applies this requirement to wall plugs, cordage, IEC 320 plugs, IEC 320 appliance inputs, and everything else in the primary power path. NOTE: Our Product Safety folks believe that this deviation is based on the National Electrical Code's requirement that a single unit may draw no more than 80% of the branch-circuit rating. I.e., for a 15A branch circuit no device on it can be rated to draw more than 12A, or 16A on a 20A branch circuit. If you look through vendor catalogs and websites, you can find some dual-rated IEC 320-C13 plugs and IEC 320-C14 appliance inputs: * UL/CSA ratings of 15A. * European ratings of 10A. This is not a matter of different physics across the Big Pond, but of manufacturers asking UL and CSA to test their devices at higher currents than the European standards specify for IEC 320 devices, just for people like you and me who need to draw slightly more than 1100-1200W primary power. Thus these linecords and appliance inlets will legally let you draw up to 12A continuous at a nominal 110-120VAC, and up to 10A continuous at a nominal 220-240VAC, thereby meeting your requirements. John Barnes Advisory Engineer Lexmark International Hare, Paul phare%pirus@interlock.lexmark.com on 06/13/2001 02:42:01 PM Please respond to Hare, Paul phare%pirus@interlock.lexmark.com To: emc-pstc%majordomo.ieee@interlock.lexmark.com cc:(bcc: John Barnes/Lex/Lexmark) Subject: Detachable AC Cordset Selection for the EU Hello group, I am in the process of specifying detachable AC cordsets for European distribution of my product. It uses an autoranging power supply (100-240VAC) and is rated for 12 A max with a C14 appliance coupler. I initially thought this would be a trivial task of matching plug and connector variations for each of the EU countries and specifying a 12 A cord. However, it looks like all the cordsets that are generally available with European connectors are rated for 10 A max. I am also lead to believe that the C14 coupler is rated for 15A in North America, but only 10 amps in Europe. Are electrons hotter on the east side of the pond?? Amongst my circle of compliance peers, there seems to be a difference of opinion as to what current rating the cordset should have. I would think that the current rating of any cordset I choose for Europe would need to be rated for 12A (Better safe than sorry, right?). But half of the people I've talked to say, But why? The current will be about half of the 12A max, or 6 amps, due to the higher line voltage. And after all, the mains voltage should be within 10% of nominal!! Therefore a 10A cordset is plenty good! If I had my way, I would special order a 12A cordset (And I guess this would change my appliance coupler?). But, it would be nice if I could buy an off-the-shelf 10A cordset because of pricing and availability issues. Any comments? Thanks in advance, Paul Hare ph...@pirus.com --- 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, --- 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: [SI-LIST] : Shielding Effectivness Question
Neven, To analyze the noise picked up by a wire that crosses a hole/slot in a shield, look at: [831] Lin, Guoxian, Electromagnetic Excitation of a Wire Crossing a Long Slot in an Infinite Plane, Electromagnetic Compatibility 1989, Zurich, Switzerland, Mar. 7-9, 1989, pp. 89-92. [938] Nakano, Hisamatsu, Yamauchi, Junji, Eda, Masahiro, and Iwasaki, Takeshi, Numerical Analysis of Electromagnetic Couplings Between Wires and Slots Using Integral Equations, 4th International Conference on Antennas and Propagation (ICAP 85), Coventry, UK, Apr. 16-19, 1985, pp. 438-442. [966] Parmantier, J. P., and Aparicio, J. P., Electromagnetic Topology: Coupling of Two Wires Through an Aperture, Electromagnetic Compatibility 1991, Zurich, Switzerland, Mar. 12-14, 1991, pp. 595-600. [1211] Taylor, Clayborne D., Marcum, Frank, Prather, William D., and Herrmann, Carl C., On Using a Sense Wire to Quantitate the Magnetic Flux Leakage Through an Aperture in an Electromagnetic Shield, IEEE Transactions on Electromagnetic Compatibility, vol. 31 no. 4, pp. 337-341, Nov. 1989. My article on Designing Electronic Equipment for ESD-Immunity is being edited by Printed Circuit Design magazine, and should appear on their webpage http://www.pcdmag.com/ pretty soon now. Just last week I received several E-mails from Andy Shaughnessy asking for clarification of points in my article. My list of references, which is supposed to be posted with the article, covers 70-some books and booklets, and about 1300 pertinent standards/reports/papers/articles gleaned from engineering and physics publications going back to the mid-1970's. John Barnes Advisory Engineer Lexmark International To unsubscribe from si-list or si-list-digest: send e-mail to majord...@silab.eng.sun.com. In the BODY of message put: UNSUBSCRIBE si-list or UNSUBSCRIBE si-list-digest, for more help, put HELP. si-list archives are accessible at http://www.qsl.net/wb6tpu
RE: Secondary Grounding
Martin, I agree with Peter about designing even Class I (grounded) power supplies with Class II (double-insulated) internal construction. Our Product Safety folks require this, and have required it going back to our IBM Lexington days. The grounding of wall outlets can not be trusted in many countries. In Japan, for example, most houses are wired with NEMA WD-1 1-15P style wall outlets (see plug 1 on my webpage ftp://ftp.lexmark.com/pub/networking/internat.htm ). For some printers going to Japan we use a special linecord having a NEMA WD-1 1-15P plug with a separate ground wire ending in a spade lug. Our instructions tell the user to mount this lug under the screw that holds the faceplate to the wall outlet, but we know that must of them ignore the ground wire or even cut the wire off the plug. So on a Class I power supply we may use the ground connection to control conducted emissions, but we do not depend on it for safety. John Barnes Advisory Engineer Lexmark International --- 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: Korean Power Cord ??????
Gary, The best specifications that I have found are: * South Korea 220V +/-10%, 60Hz +/-4%. * North Korea 220V +6.8% -13.6%, 60Hz +0.0% -5.0%. We use linecords with Schuko (CEE7 VII) plugs for both countries. South Korea changed from a 110V 60Hz standard a few years ago. For several years they required all electronic products imported into their country to operate only on 220V power, to force their people to make the changeover. This was a real pain for us, because we prefer to design our power supplies to have an IEC 320-C13 or IEC 320-C7 appliance input, and operate from 90-265V 47-63Hz, to minimize the number of product variants we have to manufacture and control. The last I heard, a couple of years ago, South Korea was again permitting products with universal power supplies to be imported since their primary-power changeover was complete. One of our Product Safety Engineers and I have put together a webpage that summarizes 54 sources of information on primary voltages, frequencies, plugs, languages, and safety-approval marks for 310 counties. We will make it publicly available as soon as my manager gives his okay. John Barnes Advisory Engineer Lexmark International --- 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: AC Power Primer?
Andrew Carson acar...@uk.xyratex.com wrote: With phase connected to the phase terminal and neutral connected to the neutral terminal, the international version was fine on the immunities. It was only when the PSU was connected to a phase to phase supply, or the phase and neutral reversed, that the problem became apparent. An example of, despite outward appearances, not all supplies can be reliably connected to phase to phase or any input terminal to phase and the other to neutral. An aspect that I just heard of yesterday, from one of our Product Safety engineers, is that Australia, Argentina, and the People's Republic of China have what looks like the identical plug. The Australian plug is used over much of the South Pacific. The prongs for the Chinese plug are 1mm longer than the prongs in the Australian plug. The prongs in the Argentina plug are 1mm longer that the prongs in the Australian plug, AND hot and neutral are swapped! John Barnes Advisory Engineer Lexmark International --- 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: ESD generators max Contact discharge level
Glyn, I just ran across this paper, which discusses in greater detail how lower ESD voltages can sometimes create greater upset of electronic equipment than high ESD voltages: [496a] Fujiwara, Osamu, An Analytical Approach to Model Indirect Effect Caused by Electrostatic Discharge, IEICE Transactions on Communications, vol. E-79B no. 4, pp. 483-489, Apr. 4, 1996. (download from http://search.ieice.or.jp/1996/pdf/e79-b_4_483.pdf) John Barnes Advisory Engineer Lexmark International -- Forwarded by John Barnes/Lex/Lexmark on 04/24/2001 11:26 AM --- John Barnes 04/23/2001 10:56 AM To: Glyn Garside(TUV) ggarside%us.tuv@interlock.lexmark.com cc: Subject: Re: ESD generators max Contact discharge level (Document link: JRBARNES Mail) Glyn, I have submitted a 21-page article on Designing Electronic Equipment for ESD Immunity to Printed Circuit Design magazine. In my literature search, I read over 70 books and nearly 1300 articles/papers/standards/application notes on Electrostatic Discharge (ESD) and related subjects over the last five months According to various authors, air-discharge voltages in the range of 4-6kV are the most likely to upset electronic equipment. At higher voltages you start getting corona from the person/air-discharge tip, which: 1. Slows down or eliminates the initial spike of the ESD zap, which 2. Slows down the risetime of the ESD zap from 0.5-1ns to some 5-10ns, which 3. Narrows the frequency range of the ESD zap from some 1-500MHz down to 1-60MHz or so, which 4. Makes slots and other imperfections in shields look much smaller with respect to the wavelengths of the ESD zap's magnetic and electric fields, greatly reducing leakage through the shields, AND Making unterminated wires, loops, and patches look much smaller than the wavelengths of the fields, greatly reducing coupling into victim circuits: * A monopole (a wire sticking up from a groundplane) is a very efficient antenna when its length is about n * lambda / 4, with n odd. * A dipole is a very efficient antenna when its length is about n * lambda / 2, with n odd. * A loop is a very efficient antenna when its length is about n * lambda, with n odd. There are a bunch of other effects, including resonances in shielded enclosures, resonances with parasitic capacitance/inductance, dI/dt, etc. But in general the wider frequency range of low-voltage ESD has a much higher chance of getting us than the high energy of high-voltage ESD. If we use filters without surge protection on input/output (I/O) lines, the energy that can sneak through is proportional to the square of the ESD voltage. So for direct discharges, high ESD voltages will dump more energy into the circuit than low ESD voltages, and thus increase the chances of damage/upset. Since it only takes one coupling path and one susceptible circuit to clobber a product, in our testing we need to make sure that we haven't left any windows of opportunity open for ESD. One author recommends ramping up the voltage for ESD tests in 1kV steps. All the others recommend using 2kV steps unless you have reasons to suspect otherwise (such as a narrow window that showed up in a similar product or earlier tests). Quite a few authors also suggest testing to at least 1-2kV above the specified limit to make sure you have some margin. The draft of EN 61000-4-2 that Doug Smith made available to us suggests using 2kV steps in the absence of other requirements (page 21). To reduce the confounding effect of relative humidity on corona and thus on air discharges, all of the current ESD standards that I've seen basically specify that: 1. the ESD simulator should approach the EUT as quickly as possible without causing damage to the EUT or simulator (IEC 61000-4-2 draft page 21). 2. The simulator ... should be followed through until the electrode touches the surface. (ditto). John Barnes Advisory Engineer Lexmark International [3] Electrostatic Discharge (ESD) Protection Test Handbook, 2nd ed. KeyTek Instruments Corp., Burlington, MA, 1986. [17] Boxleitner, Warren, Electrostatic Discharge and Electronic Equipment-- A Practical Guide for Designing to Prevent ESD Problems. IEEE Press, New York, 1989. [32] Greason, William D., Electrostatic Damage in Electronics: Devices and Systems. John Wiley Sons, New York, 1987. [34] Hartal, Oren, Electromagnetic Compatibility By Design 4th ed. RB Enterprises, West Conshohocken, PA, 1996. [39] Kimmel, William D, and Gerke, Daryl D., Electromagnetic Compatibility in Medical Equipment. IEEE Press and Interpharm Press, Piscataway, NY, 1995. [41] Kodali, V. Prasad, Engineering Electromagnetic Compatibility. IEEE Press
Re: ESD generators max Contact discharge level
Glyn Garside(TUV) ggarside%us.tuv@interlock.lexmark.com on 04/21/2001 12:57:30 AM Please respond to Glyn Garside(TUV) ggarside%us.tuv@interlock.lexmark.com To: Douglas C. Smith doug%emcesd@interlock.lexmark.com cc: emc-pstc%ieee@interlock.lexmark.com, owner-emc-pstc%ieee@interlock.lexmark.com, Terry Meck tjmeck%accusort@interlock.lexmark.com (bcc: John Barnes/Lex/Lexmark) Subject: Re: ESD generators max Contact discharge level On the other hand very low voltage (and energy) events, such as jingling change have very high di/dt because of the tens of ps risetimes that occur at low voltage. I think this is why, as I recall, some (maybe all?) IEC standards require you to test not only to the ESD level indicated, but also the lower levels too. For example, if you are required to test at level 4, you are also required test at levels 3, 2 and 1. This is counter-intuitive -- Surely the highest voltage is the worst case? -- but apparently grounded in good physics, which Doug explains better than I would. PS: As to testing at higher levels than typical IEC values, I have read that the human body can, rarely, gain a charge of up to about 30kV(??), in conditions of low RH. Others may have better insight into this. Also, some manufacturers may want to build some margin into their test results: if five samples pass at 8kV, how sure can you be that the next 995 production units would also pass? PPS: I have a question of my own, drifting off topic slightly: if the relative humidity was fairly high when you passed the ESD test, and you retest (esp. air discharge?, or indirect discharge?) some months later when humidity is lower, could the same EUT now fail? (I think the answer is, yes?) Best Regards, Glyn Glyn R. Garside (mailto:ggars...@us.tuv.com) Senior Engineer, Industrial Machinery Division TUV Rheinland of North America, Inc. (Chicago Office) 1945 Techny Rd, Unit 4, NORTHBROOK, IL 60062-5357, USA http://www.us.tuv.com --- 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: 950 Pollution degree detirmination
The interpretation that IBM/Lexmark's safety folks have always given me is that Pollution Degree 1 applies to sealed units such as the inner layers of multilayer Printed Circuit Boards (PCB's) or potted modules. John Barnes Advisory Engineer Lexmark International --- 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: Spacings from Shielded Enclosure to Floating GND
Peter, I looked through some of my books last night and this morning, and found suggested spacings of: * Greater than 20mm, 8.4mm, 5mm, or 10mm between circuits and: - Points that a person could touch. - Ungrounded metal parts that a person could touch. * Greater than 2.2mm, 0.5mm, or 1mm between circuits (including traces on printed circuit boards) and chassis ground. The first set of spacings is to prevent direct electrostatic discharge (ESD) to the circuit. The second set of spacings is to prevent secondary arcing due to L * dI/dt voltage rise on the bonding wires/straps when carrying the current from an ESD hit. Page 28 or 218 (I can't read my own notes) of Boxleitner, Warren, Electrostatic Discharge and Electronic Equipment-- A Practical Guide for Designing to Prevent ESD Problems (IEEE Press, New York, 1989) suggested the 20mm and 2.2mm spacings. Pages 337 and 344 of Ott, Henry, Noise Reduction Techniques in Electronic Systems, 2nd ed. (John Wiley Sons, New York, 1988) suggested the 8.4mm and 0.5mm spacings. Page 369 of Hartal, Oren, Electromagnetic Compatibility By Design 4th ed. (RB Enterprises, West Conshohocken, PA, 1996) suggested the 5mm spacing. Page 677 of Paul, Clayton R., Introduction to Electromagnetic Compatibility (John Wiley Sons, New York, 1992) suggested the 10mm and 1mm spacings, based on air having a breakdown voltage of about 3kV/mm. John Barnes Advisor Engineer Lexmark International --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. 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: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
RE: Product Robustness -- ESD
Dwight, According to Keytek Instrument Corp.'sPulsed EMI Handbook the use of crossed-vane ESD simulators is covered by: * ANSI C63 (searching the Internet led me toAmerican National Standard Guide for Electrostatic Discharge Test Methodologies and Criteria for Electronic Equipment, ANSI C63.16-1993. ) * European Computer Manufacturers Association, Electrostatic Discharge Immunity Testing of Information Technology Equipment, ECMA TR/40, July 1987. The engineer who is our keeper of Electromagnetic Compatibility/Electrostatic Discharge (EMC/ESD) standards seems to be out today, so I haven't had a chance to verify the ANSI standard yet. I did find it available to IEEE members for $54 athttp://www.standards.ieee.org/catalog/electromag.html versus the $101 list price from ANSI. ECMA TR/40 can be downloaded for free from ftp://ftp.ecma.ch/ecma-tr/tr-040.pdf and does discuss construction and use of crossed-vane ESD testers. John Barnes Advisory Engineer Lexmark International --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. 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: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
Re:European connectors
Jim, Daniel, CEE 7-7, CEE 7/7, and CEE7 VII all refer to the 250V 16A Schuko plug commonly used in Europe. http://www.internationalconfig.com/config_chart/index.htmshows it at the very top. John Barnes Advisory Engineer Lexmark International --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. 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: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
Re: Site Correlation
Joe, If the transmitting antenna (your product) and the receiving antenna were in free space, you pretty much could assume that the radiation falls off at 1/r^2, and thus use a 10.5dB correction factor between 10m and 3m measurements. (You might have to worry about near-field effects and antenna interaction at low frequencies.) But Radiated Emissions measurements for equipment are done over a ground plane. Thus the receiving antenna sees: * Direct radiation from the equipment. AND * Radiation that has bounced off the ground plane. Because of the difference in path lengths, these signals may sum anywhere from exactly in-phase to exactly out-of-phase, depending on the frequency and antenna heights. For horizontal antennas this turns out to be just a small disturbing factor, less than 1dB or so. But vertical antennas can see anywhere from 200% to 0% of the free-space voltage for that same position of the antennas. Because the FCC and CISPR regulations require you to vary the receive antenna height between 1m and 4m, you will see lobes in the vertical pattern because of this constructive/destructive interference. After having some of our products pass easily in our 3m chamber, and then fail miserably on a 10m test site, our EMC folks came up with an additional correction for: * Transmitting antenna height of 1m (tabletop product on 0.8m high table). * Receive antenna height of 1-1.75m in our 3m chamber. * Receive antenna height of 1-4m on a 10m site. * Frequencies from 30MHz to 1GHz. This Vertical Correction Factor (VCF) is: * About 1dB at 30MHz. * About 7dB at 200MHz. * About 1dB at 1GHZ. Thus, if I am testing a product in our 3m chamber, and want to be sure that it will pass the official tests at 10m, at 200MHz I had better see vertical emissions no higher than 3.5dB (10.5dB for 1/r^2 minus 7dB VCF) above the 10m limit. Because of Murphy's Law, and to protect us from slight variations in production, our EMC folks like us to have 4dB margin against this corrected limit. If we are within 2dB of this corrected limit, we may pass Radiated Emissions tests on the initial units, but will have to rerun A-B Radiated Emissions tests in our 3m chamber for *any* contemplated changes to the product, and may have to test production units regularly to make sure that we stay legal. This is not a fun way for us Design Engineers to spend our time... Thus we tend to overdesign the products, which adds cost. We have had a 10m Open Air Test Site (OATS) here for a number of years. But because of Kentucky weather, we could only count on being able to use it about 5-6 months per year. For another couple of months per year we could hope/pray for a warm day to run 10m tests, but expected to have to travel to a closed-in 10m test site. But, in late October we started construction of a new lab building that will have a completely-equipped 10m semi-anechoic/anechoic chamber. It's supposed to be completed in late summer. Yeehah! John Barnes Advisory Engineer Lexmark International --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. 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: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
RE: EN 61000-6-2 Table 2.3 inticates signal ports = 30 M +/- 1k v?
Terry, I don't have a copy of EN 61000-6-2, but it sounds similar to the IBM Lightning Surge Susceptibility (LSS) test that we do on our network adapters during development/qualification. We LSS test all products that have: * Cables going outdoors through surge protectors, OR * Indoor cables longer than 120 meters (and for our own peace of mind, ones with shorter network cables too), just for the reasons that Michael Hopkins gave. In our test procedure we: 1. Make sure that the network adapter is working with the network. 2. Disconnect the network adapter from the network, and connect it to the Keytek surge generator. 3. Hit the product with 1 to 10 simulated lightning surges, between a specified set of signals/shields at a given voltage and polarity. 4. Disconnect the network adapter from the surge generator, and reconnect it to the network. 5. Verify that the network adapter still works with the network. This may require resetting/powering-down powering-up the network adapter and its associated equipment in some cases. Our concern is that we don't damage the network adapter. Upsetting it, or locking it up in a way that require manual intervention, are okay. 6. Repeat the process until we have hit every specified signal/signal or signal/shield pair with 10 positive zaps and 10 negative zaps at the maximum specified voltage. The test only calls for us to zap the cable interface at the maximum voltages. But, having blown up a number of cards with this test since 1990, I like to test at 25%, 50%, 75%, and then 100% of the maximum specified voltage, at least for the first time I am testing a brand new design. I've also seen failures where I had to zap a card several times before I destroyed it, and other times that the very first zap at a voltage/polarity destroyed a part. Depending on my confidence level, I may: * Zap the card 10 times at a voltage/polarity before I check to see if it still works. OR * Change the voltage/polarity/test-point, zap the card once and check it, then zap it another 9 times and recheck it before going to a new voltage/polarity/test-point. John Barnes Advisory Engineer Lexmark International --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. 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: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
Re: Crossed Vane ESD Simulator
Sandy, IBM developed a Tabletop Electrostatic Discharge (ESD) test using a crossed-vane ESD simulator, which we still use here at Lexmark to supplement IEC 61000-4-2 ESD testing. (We used to be IBM Lexmark.) I just ran across an article about it a week ago in my research into methods of hardening electronic products against ESD, I believe: Calcavecchio, Ralph J., and Pratt, Daniel J., A Standard Test to Determine the Susceptibility of a Machine to Electrostatic Discharge, 1986 IEEE International Symposium on Electromagnetic Compatibility Symposium Record, San Diego, CA, Sept. 16-18, 1986, pp. 475-482. Our test setup has an aluminum plate bolted to the middle of the long edge of a metal table, about 60 inches x 30 inches. A grounding wire with a couple of series resistors connects the table to the groundplane (metal raised floor) in the lab. We put the Equipment Under Test (EUT) on the table, with its front edge lined up with the edge of the table and approximately centered on the metal plate. Then we put the crossed-vane simulator in front and roughly parallel to the table, with the probe touching the center of the metal plate. The top view is something like this: +--+ ! !-/\/\/ ground plane ! ! ! ! ! ! !+-+ ! !! ! ! !! ! ! !! EUT ! ! !! ! ! ++---===---+---+ A ! ! \ / X / \ ! ! As I understand the theory behind the crossed-vane ESD tester, the vanes provide free-space capacitance. Because this capacitance is to every conductive item in the vicinity, it has negligible inductance and thus will discharge very quickly (fraction of a nanosecond rising edge?) when the relay in the probe closes. This hits the EUT with impulses covering a very-wide frequency span, exciting all the antennas (dipoles, monopoles, and loops) that we have accidently designed into the product and causing Non-Linear Rectification anywhere we are susceptible. John Barnes Advisory Engineer Lexmark International --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. 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: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
RE: Coaxial cable
Richard, The term that I ran across many times while researching my book was optical coverage-- as though you put a light bulb inside the shield and measured what percentage of its light leaked out. The basic assumptions are: 1. Electric and magnetic fields inside the shield are totally blocked by the picks (conductive wires/strips/foil in a group), so the only leakage is through the holes between picks. 2. The fields that leak out are incoherent, and thus add as scalars (sum of magnitudes) for the peak leakage. This is a first-level approximation, and is closely related to a discussion of the shielding effectiveness of arrays of holes/ honeycomb on this mailing list a couple of weeks ago. Over a wide range of frequencies, and far enough away from the shield that the openings seem to blur together, the leakage is approximately proportional to how much of the inside/ other side of the shield is exposed to our view. But at specific frequencies, or if we get very close to a hole in the shield, we get diffraction and constructive-/distructive-interference that cause lobes and notches in the leakage fields. Some companies have tried to take advantage of this for special (high-priced) single-function cables. Optimal braiding selects the gauge and number of wires in each pick (group of wires laid parallel to one another) and carefully controls their crossing angle during construction of the cable. The idea is to create holes with a certain size and shape, and thus polarizability, and with a certain spacing lengthwise and around the cable. The authors of the articles claimed that at the design frequency they would get distructive interference, just like a diffraction grating, making the holes in the shield appear smaller than they really were. The problem that I saw with this scheme was that at other frequencies, or if you bent/pulled/deformed the cable in any way, the geometry changed and you would get an *increase* in emissions. So it always seemed more sensible to me to try to completely seal the electric and magnetic fields inside the cable/shield and not optimize just one tiny operating point. John Barnes Advisory Engineer Lexmark International author of Electronic System Design: Interference and Noise Control Techniques (Prentice-Hall, 1987) richardg%exabyte@interlock.lexmark.com on 11/07/2000 12:11:36 PM To: john_barnes.lexm...@sweeper.lex.lexmark.com cc:(bcc: John Barnes/Lex/Lexmark) Subject: RE: Coaxial cable John, Couldn't quite follow the optical coverage reference. Sounds like it should be optimal coverage for copper wire cable verses optic cable. Thanks. Richard Georgerian Technical Committee 8 Product Safety (TC-8), Vice-chair Colorado Product Safety Technical Committee (CPSTC), Chair Product Compliance Engineer Exabyte 1685 38th Street Boulder, CO 80301 USA tel.: 303-417-7537 fax: 303-417-5710mailto:richa...@exabyte.com -Original Message- From: jrbar...@lexmark.com [mailto:jrbar...@lexmark.com] Sent: Tuesday, November 07, 2000 9:58 AM To: sergioro...@siemens.com.br; emc-p...@ieee.org Subject: Re: Coaxial cable Sergio, A foil braid shield is quite common on high-speed cables. If a cable is properly terminated and you don't have common-mode problems, most of its radiated emissions will be from holes in the shield. Thus optical coverage, the percentage of the shield's nominal area that is actually covered by wires/conductive foil, is a reasonable approximation to the shielding effectiveness. It is very difficult to braid wires in a way that achieves over 95% optical coverage. A foil shield, with the overlap folded over so the conductive surfaces touch, can easily achieve 100% optical coverage, but is fragile. If a foil-shielded cable vibrates, or is repeatedly bent, the foil will eventually tear. Even if end-to-end continuity is retained, this hole in the shield can cause a great increase in radiated emissions. By braiding wires over the foil, you start out with 100% optical coverage, and if/when the foil tears degrade in just that area to the 90-95% optical coverage of the braid. We used to use a type of parallel cable for Electromagnetic Compatibility (EMC) testing that had a foil shield. We would get about three weeks use out of these before they went bad and had to be thrown away because of excessive radiated emissions. I helped develop and release an IEEE-1284 parallel cable in 1994 (Lexmark partnumber 1329605) that used a foil braid shield, and we put these in our EMC lab. It took nine months of heavy use before the first of these cables exhibited a noticeable increase in emissions over brand-new cables. John Barnes Advisory Engineer Lexmark International --- This message is from the IEEE EMC Society Product Safety
Re: Coaxial cable
Sergio, A foil braid shield is quite common on high-speed cables. If a cable is properly terminated and you don't have common-mode problems, most of its radiated emissions will be from holes in the shield. Thus optical coverage, the percentage of the shield's nominal area that is actually covered by wires/conductive foil, is a reasonable approximation to the shielding effectiveness. It is very difficult to braid wires in a way that achieves over 95% optical coverage. A foil shield, with the overlap folded over so the conductive surfaces touch, can easily achieve 100% optical coverage, but is fragile. If a foil-shielded cable vibrates, or is repeatedly bent, the foil will eventually tear. Even if end-to-end continuity is retained, this hole in the shield can cause a great increase in radiated emissions. By braiding wires over the foil, you start out with 100% optical coverage, and if/when the foil tears degrade in just that area to the 90-95% optical coverage of the braid. We used to use a type of parallel cable for Electromagnetic Compatibility (EMC) testing that had a foil shield. We would get about three weeks use out of these before they went bad and had to be thrown away because of excessive radiated emissions. I helped develop and release an IEEE-1284 parallel cable in 1994 (Lexmark partnumber 1329605) that used a foil braid shield, and we put these in our EMC lab. It took nine months of heavy use before the first of these cables exhibited a noticeable increase in emissions over brand-new cables. John Barnes Advisory Engineer Lexmark International --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. 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: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
DC Fuse for Power Supply
Doug, I ran into a problem in 1990 where we needed to add a primary fuse to a brick power supply, without changing the circuit board or the case. We had two holes in the circuit board where we could install a pigtailed fuse if we could find one that would meet UL and SEMKO requirements. (SEMKO did not allow soldered-on pigtails on primary fuses). Our solution, and I have yet to see a better alternative, was to buy 5mm x 20mm fuses from Schurter with push-on endcaps. These endcaps have the lead wires welded on, meeting the word and the spirit of the EMKO Deviations that applied at that time. Since no heat is applied when these endcaps are installed on the fuses, they have no effect on their electrical characteristics. I've given my Schurter catalog to the engineer who's taken over specifying/qualifying power supplies from me, so I don't have the part number handy, and I don't know if these fuses are available in the rating you need. But this, or something like this, might get you out of your bind. John Barnes Advisory Engineer Lexmark International --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. 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: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
Re: Fwd:information regarding electromagnetic compatibility
Evangelos Tonas wrote an article EM Shielding Effectiveness of Low-cost Architectural Shielding Materials that appeared in the 1997 ITEM. This article is available on the web at http://www.rbitem.com/ITEM_Publications/ITEM_Archives/I97art19.htm Table 1 shows that chicken wire can achieve: * 35 to 48dB shielding against electric fields (E-fields) from 10kHz to 10MHz. * 25 to 33 dB shielding against plane-wave fields from 40MHz to 400MHz. John Barnes --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. 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: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
Re: Fwd:information regarding electromagnetic compatibility
Gerald, R. Kenneth Keenan's book Digital Design for Interference Specifications (Vienna, Virginia: The Keenan Corporation, 1983) has some excellent advice for doing developmental tests in chapter 6. He tells: * How to do basic emissions tests using: - An AM broadcast receiver. - An FM broadcast. - Or an inexpensive wide-band receiver. * How to make basic test accessories such as a: - Line-Impedance Stabilization Network (LISN) for conducted emissions testing. - Rotating folded-dipole antenna for radiated emissions testing. The techniques/equipment that he describes will let you do *comparative* measurements. If you have a problem because of ambients (radio, TV, pagers, police/fire/emergency radio systems) you can easily build a simple shielded room out of wood strips and chicken wire, being sure to overlap every seam by several inches to provide good electrical contact and waveguide-below-cutoff effects. You can reduce problems with standing waves by building the walls and ceiling so that they are not parallel to one another-- a couple degrees off square will probably be enough. If you always put the device-under-test (DUT), the antenna and receiver, and yourself (use chalk or tape to mark the position of your feet for making measurements) in close to the same positions you can get some pretty decent semi-quantitative measurements using this type of shielded room, for a very small investment in materials and time. John Barnes Advisory Engineer Lexmark International author of Electronic System Design: Interference and Noise Control Techniques (Prentice-Hall, 1987) --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. 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: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
Re: Sizes for Power, Control and Signal Cords/Cables/Wires
RE: Correction factor for power supply cords.
Rick, We were developing the power supply for the Lexmark MarkNet Pro External Print Servers. The power supply has a Y-cable with: * A shrouded male IEC-320 sheet C14 connector on one end. * A female IEC-320 sheet C13 plug. * Soldered connections to the power supply card in the middle. This was to be a cost reduction from the scheme we used on the Lexmark MarkNet XLe, where we used an IEC-320 appliance inlet/outlet on the power supply card with a jumper cable having IEC-320 C14 and IEC-320 C13 connectors. In both cases the power supplies had worldwide approvals (UL, CSA, TUV, SAA, MITI, and various Nordic approvals) and the idea was to steal a printer's linecord to make connection to the wall outlet. This way each model only had one top bill-of-material for worldwide use, versus over nine top bills-of-material per model for the IBM 4033 where we shipped separate linecords for: * US/Canada (NEMA WD-1 5-15P plug). * Australia/New Zealand (AS 3112 plug). * Continental Europe (CEE 7 VII, or Schuko plug). * Denmark (Afsnit 107 plug). * Africa (GG 164 plug). * United Kingdom (BS 1363 plug). * Switzerland (1011-S24507 plug). * Italy (CEI 23-16 plug). * Israel (SI 32 plug). To the safety agencies, we now had a weird hybrid of a regular power supply and an extension cord to the printer. Our original intent was to rate the auxiliary output at just under 12A for 100-120VAC and just under 10A for 220-240VAC, by using: * 13A cordage. * IEC-320 connectors rated for 15A by UL and CSA, and for 10A by other (220-240VAC country) safety agencies. With UL's interpretation of attachment plug as including the cordage, we needed to find = 15A cordage or back off our input-current rating to under 10.4A. We wound up doing the latter because we could not find cordage that: * Had UL, CSA, and Harmonized approvals. * Was rated = 15A by UL and CSA. * Was rated = 10A by other safety agencies. AND * Would fit into IEC-320 sheet C13 and C14 connectors that had all these ratings/approvals. John Barnes Advisory Engineer Lexmark International --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. 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: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
Re: Correction factor for power supply cords.
Kelly, UL 1950 has a D1 (more restrictive) deviation in clause 3.2.1 than IEC 950: Where equipment is intended to be connected to a source of supply by a power supply cord, the attachment plug shall be rated no less than 125 percent of the rated current of the equipment. We got into a tussle with UL over this about four years ago on one of my power supplies. After two weeks of discussions with them we wound up accepting their interpretation of attachment plug as including the wall plug itself, the AC cordage, and any IEC-320 plugs/sockets/appliance inlets between the wall outlet and the common-mode choke of the power supply. Power Dynamics and other companies make IEC-320 plugs/sockets/appliance inlets that are rated 15A by UL and CSA, and 10A by the Europeans. But the specific approvals (wall plug to cordage, IEC-320 plug/socket to cordage) at that time only went up to 16AWG wire which is rated for 13A by UL and CSA. We wound up limiting the auxiliary-output current to 9.8A, for a maximum total input current of 10A to keep UL happy. John Barnes Advisory Engineer Lexmark International --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. 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: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
Re: Correction factor for power supply cords.
Kelly, UL 1950 has a D1 (more restrictive) deviation in clause 3.2.1: Where equipment is intended to be connected to a source of supply by a power supply cord, the attachment plug shall be rated no less than 125 percent of the rated current of the equipment. UL's interpretation of attachment plug includes not only the plug that goes into the wall outlet, but the entire path between the wall outlet and your power supply, including: * Wall plug. * Cordage. * IEC-320 plug. * IEC-320 appliance inlet. John Barnes Advisory Engineer Lexmark International -- Forwarded by John Barnes/Lex/Lexmark on 03/10/2000 10:50 AM --- wolfgang_josenhans%mw.3com@interlock.lexmark.com on 03/10/2000 10:09:58 AM Please respond to wolfgang_josenhans%mw.3com@interlock.lexmark.com To: ktsudama%cisco@interlock.lexmark.com cc: emc-pstc%majordomo.ieee@interlock.lexmark.com (bcc: John Barnes/Lex/Lexmark) Subject: Re: Correction factor for power supply cords. Kelly, You derate the cord with respect to the ampacity allowed by the receptacle it connects to. Art. 210-23 of the NEC indicates that cord connected equipment can draw no more than 80 % of the maximum receptacle rating. Regards, Wolf Josenhans Kelly Tsudama ktsud...@cisco.com on 03/09/2000 09:33:14 PM Please respond to Kelly Tsudama ktsud...@cisco.com Sent by: Kelly Tsudama ktsud...@cisco.com To: emc-p...@majordomo.ieee.org cc:(Wolfgang Josenhans/MW/US/3Com) Subject: Correction factor for power supply cords. Hi Group I am hoping that I can get your opinions with an issue regarding the correction factor of power supply cords. For instance, in the NEC table 310-17, for single conductors in free air, there is a chart at the bottom of the table that allows you to determine how to factor in the ambient temperature. However, for a flexible power cord, the table 400-5 does not have any correction factor table. At first I thought that this is because cords always have a temperature rating marked on them, but then I recall that most (if not all) single conductors have this marking too Is there a need to de-rate a power cord's current rating based on the expected ambient temperature? If so, where in the NEC did I miss this fact? If not, why not? Thanks for your help, Kelly Kelly Tsudama Cisco Systems ktsud...@cisco.com 408-527-0216 408-525-9150 fax 408-322-9024 pager --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. 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: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. 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: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. 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: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
Re: Source for leadless high-voltage capacitors?
Scott, Have you tried looking at high-voltage chip capacitors? AVX for example offers up to 18,000pF at 3000V and 5600pF at 4000V in a 3640 (nominally 0.36 x 0.40 footprint) package in an X7R dielectric. See pages 20 to 24 of the AVX Multilayer Ceramic Chip Capacitor catalog. John Barnes Advisory Engineer Lexmark International slacey%foxboro@interlock.lexmark.com on 03/09/2000 10:57:20 AM Please respond to slacey%foxboro@interlock.lexmark.com To: emc-pstc%ieee@interlock.lexmark.com cc:(bcc: John Barnes/Lex/Lexmark) Subject: Source for leadless high-voltage capacitors? To the group, I am looking for a source for leadless disc capacitors. I require 10,000 pF of at least 3kV. Basically, what I'm looking for is to buy capacitors that have not yet had the lead attachment and coating operations performed. I am trying to eliminate the lead inductance. Scott Lacey --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. 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: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. 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: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
Re: Operating Tolerance
Jess, Most of my reference sources show the US as 120VAC +/-5% 60Hz +/-0.3% and Argentina as 220VAC +/-10% 50Hz +/-2%. The 1996 World Electricity Supplies shows: * Charlotte, North Carolina as 120VAC +5-2.5% 60Hz +/-0.06%. * Detroit, Michigan as 120VAC +4-6.6% 60Hz +/-0.2%. * Los Angeles, California as 120VAC +/-5% 60Hz +/-0.2%. * Miami, Florida as 120VAC +/-5% 60Hz +/-0.3%. * Pittsburg, Pennsylvania as 120VAC +/-5% for lighting, +/-10% for power, 60Hz +/-0.3%. * San Francisco, Callifornia as 120VAC +/-5% 60Hz +/-0.08%. * Toledo, Ohio as 120VAC +/-5% 60Hz +/-0.08%. * Argentina as 220V +/-10% for overhead cables, +/-7% for underground cables, 50Hz +/-2%. John Barnes Advisory Engineer Lexmark International sbtan%ctlsg.creaf@interlock.lexmark.com on 11/11/99 05:27:28 AM Please respond to sbtan%ctlsg.creaf@interlock.lexmark.com To: emc-pstc%majordomo.ieee@interlock.lexmark.com cc:(bcc: John Barnes/Lex/Lexmark) Subject: Operating Tolerance Hi, Could someone please advise if the supply voltage tolerance for US Argentina should be +6-10% or +/-10% of 120V for US 220V for Argentina ? Thanks in advance! Jess - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
EMC Testing of Equipment Built In-House
About a week ago one of the participants on this mailing list asked whether equipment built in-house, for a company's internal use, had to be safety and electromagnetic compatibility (EMC) tested. I just started reading Tim Williams' book EMC for Product Designers (second edition) this morning, and on page 15 came across the following statement under Scope, requirements, and exceptions for EMC Directive 89/336/EEC: Taken into service Taking into service means the first use of a product in the EU by its final user. If the product is used without being placed on the market, if for example the manufacturer is also the end user, then the protective requirements of the Directive still apply. This means that sanctions are still available in each member state to prevent the product from being used if it does not comply with the essential requirements or if it causes an actual or potential interference problem. On the other hand, it should not need to go through the conformity assessment procedures to demonstrate compliance (article 10, which describes these procedures, makes no mention of taking into service). Thus an item of special test gear built up by a lab technician for use within the campany's design department must still be designed and installed so as not to cause or suffer from interference, but should not need to follow the procedure for aplying the CE mark. John Barnes Advisory Engineer Lexmark International - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: EN50082-1:1997 EN55024
In another life, I was working for a EMC Test lab and we always used the step by step procedure which was in the ESD Standard. We tested using this procedure for years and we did encounter some products who failed at low level ESD but had no problem at higher levels. We wondered what to conclude and had some hypothesis. Benoit, Our Electromagnetic Compatibility (EMC) Lab folks require us to perform IEC 801.2 Electrostatic Discharge (ESD) tests at all test levels up to the specified maximum for the product for air discharge and contact discharge. For Horizontal Coupling Plane and Vertical Coupling Plane tests, which are not required for the CE Mark, they let us test at just the maximum voltage. During developmental tests (we fix these before we release the product to manufacturing) we have seen two forms of the effect that you describe-- that a product passes ESD testing at low and high voltages but fails at intermediate voltages. One set of symptoms was: * Product worked perfectly despite low-voltage ESD hits. * Around 8kV the product locked up occasionally. * At 15kV the product did a power-on reset (POR) and restarted itself without losing any data. We found a couple of interrupt lines going to the microprocessor that were very close to the back plate of the printer. At intermediate ESD voltages we put enough of a spike on the interrupt lines that the microprocessor would start to execute an interrupt, then hang because the interrupt went away. At higher voltage we still hung the microprocessor, but would also trigger the POR circuit starting the card up from scratch. Our fix was to add 22pF capacitors on the interrupt lines at the microprocessor, and move them well away from the edge of the card to make the card more immune to ESD. For the other case, the product would work perfectly despite low-voltage or high-voltage ESD hits, but would act up for intermediate-voltage ESD hits. This was before I became involved with EMC/ESD testing, but the explanation I heard was that the product was sensitive to the dI/dt of the ESD hits. At low-to-medium voltages dI/dt was proportional to the voltage on the ESD gun. At high voltages corona started carrying off the charge early, and effectively slowed dI/dt below the susceptibility level of the product. This is akin to bringing the gun in slowly, versus quickly (just below a speed that would damage the product) as required by IEC 801.2. John Barnes Advisory Engineer Lexmark International - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: voltage on Neutral line
What voltages can I expect on the Neutral (referenced to ground) line in various countries and connection systems? Is there a limit on how high the voltage may be, both in normal and fault conditions? Moshe, THE's booklet, World Electricity Supplies, lists the supply voltage, frequency, and power distribution systems used in over 200 countries. You can order it through Technical Standards Services, Ltd. webpage at http://www.techstandards.co.uk/thsguide.html TN and TT power systems (IEC 950 1.2.12.1 and 1.2.12.2) are the ones usually encountered. Neutral-to-ground voltages should be less than a few (5 or so) volts even under a line-to-ground fault. Hospitals and other high-reliability installations sometimes use IT power systems (IEC 950 1.2.12.3) permitting continued operation even if a line-to-ground fault occurs-- at the cost of: * Neutral-to-ground voltage approaching the single-phase line voltage. * In a three-phase system, the other phase-to-ground voltages approaching sqrt(3) times the single-phase line voltage. This can double the required creepage and clearance distances for (to us) a tiny additional market. So we specify that our products are not to be installed on IT power systems, but may be powered by an isolation transformer that gets its power from an IT power system to create a local TN-S power system. John Barnes Advisory Engineer Lexmark International - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: NEAR/ FAR FIELD CORRELATION ISSUES
Even now, correlation between 3 meters and 10 meters is not guaranteed. And further, 3 meter to 10 meter correlation is at least better (define better anyway you wish) in the horizontal. Vertically it's terrible (define terrible anyway you wish). At least in my experience. Doug, In our 3m chamber we use a Vertical Correction Factor (VCF) to account for the worst-case difference between 3m and 10m vertical Radiated Emissions measurements. We usually have +/-1dB correlation, occasionally out to +/-2dB, between measurements taken in the chamber at 3m including the VCF against official measurements taken on our 10m Open Air Test Site (OATS). We also sometimes have some measurements taken at 10m that are much better than what we predicted at 3m with VCF, meaning that we have over-engineered the product in trying to ensure that we will pass the 10m tests... The VCF is more pessimistic than the 10m CISPR limits by: * About 1dB at 30MHz, increasing to * About 7.5dB at 230MHz, dropping to * About 0dB at 450MHz and above. As I understand it, the VCF was calculated by modelling: * A transmitting dipole antenna 1m above the groundplane with a receiving antenna 3m away, at 1m to 1.7m above the groundplane (the range of available heights in our 3m chamber) VERSUS * A transmitting dipole antenna 1m above the groundplane with a receiving antenna 10m away, at 1m to 4m above the groundplane (the range of heights required by CISPR testing). maximum received signal at 10m at f MHz 10^2 VCF (f MHz) = - * -- maximum received signal at 3m at f MHz3^2 In the far field we expect the signal to drop off at 1/r^2. But for vertically-polarized signals the receiving antenna sees not only a direct-path signal but one bounced off the groundplane. These two can add to double the voltage at the receiving antenna, or subtract to nearly zero, depending on the phase difference between the two paths. Running the antenna up and down helps get away from the worst nulls, but doesn't compensate for them completely. Considering that the actual source of the radiation may be at various heights or angles, not centered on the table, and the signal may reflect off other metal pieces, the Vertical Correction Factor is a huge help to us in trying to meet the Radiated Emissions limits. John Barnes Advisory Engineer Lexmark International dmckean%corp.auspex@interlock.lexmark.com on 06/17/99 04:39:53 PM Please respond to dmckean%corp.auspex@interlock.lexmark.com To: emc-pstc%majordomo.ieee@interlock.lexmark.com cc:(bcc: John Barnes/Lex/Lexmark) Subject: Re: NEAR/ FAR FIELD CORRELATION ISSUES At 11:18 AM 6/17/99 +1000, you wrote: Greetings and Salutations! I was wondering if this could be mailed out via the epc-pstc channels. I want to know if anyone is doing any work in near/ far field correlation to commercial EMC standard limits area and possibly correspond with them with a view to exchanging notes. Hi Arun, At a former company I spent a very large amount of time trying to correlate near field probe measurements of the surface currents and voltages of a product to far field (10 meter) measurements. In brief - it didn't happen. And a product could be analyzed as being constructed of a variety of antennas - slots, corner reflectors, tuned cavity, tuned arrays, and either electric or magnetic dipoles ... each reacting it's own way in the far field. Now I'm not going to say it's impossible, but it seems to me that one must assume something to begin with instead of being able to blindly take a surface current measurement or near field measurement of X and state confidently that it WILL be Y in the far field under all circumstances. That's ultimately what one would have to be able to do without regard to the product. After a few rounds with a particular product, I've done this. I'm sure everyone at some point has done this. But with NO prior history of the product, I don't see how it's done. Regards, Doug McKean - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: Australian electricity supply
Chris, The 1996 World Electricity Supplies shows Australia as : * 50Hz +/-0.1% frequency. * 415/240V or 240/120V +/-6% for households. * 415/240V or 480/240V +/-6% for commercial. * 22kV, 11kV, or 6.6kV +/- 6% for industrial. The 1991 edition of Electric Current Abroad shows: * Albany, Kalgoorie, and Perth as nominal 250/440V. * The rest of Australia as nominal 240/415V. John Barnes Advisory Engineer Lexmark International chris.colgan%tagmclarenaudio@interlock.lexmark.com on 04/29/99 04:47:33 AM Please respond to chris.colgan%tagmclarenaudio@interlock.lexmark.com To: emc-pstc%majordomo.ieee@interlock.lexmark.com cc:(bcc: John Barnes/Lex/Lexmark) Subject: Australian electricity supply Hello group Can anyone tell me the limits of the Australian consumer mains supply voltage, ie 240V +?% -?%. I have ordered a copy of World Electricity Supplies but it hasn't arrived yet. Thanks Chris Colgan EMC Safety TAG McLaren Audio Ltd mailto:chris.col...@tagmclarenaudio.com = Authorised on 04/29/99 at 09:47:52; code 37160057E31C4EB1. - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Are Safety Approvals Required for Telephone Adapters?
We are looking at Telephone Adapters, such as those made by TeleAdapt ( http://www.teleadapt.com/web/Catalogue/Index), to go from an RJ-11 plug to phone jacks for the following countries: (Embedded image moved to file: pic14566.pcx) We have seen some adapters with UL, TUV, and CE marks. The only part of IEC 950 that looks like it would apply is Section 6.4, Protection of equipment users from overvoltages on telecommunications networks. Where we can find information on national or safety-agency approvals required for Telephone Adapters? Are there any requirements in CTR21, the latest European standard for analog modems, that apply to Telephone Adapters? John Barnes Advisory Engineer Lexmark International pic14566.pcx Description: Binary data
Re: Heat Calculation
According to a table of Conversion Factors that I found on page 18 of the December 1991 Electrical Manufacturing magazine, and keep stashed in my dictionary here at work: Watts * 3.413 = BTU's/hour I use the maximum input power (wattage) that we have measured for a product in its various operating modes, after it has been turned on and warmed up for a while. Every time that I have been asked the question it is in the context of calculating the air-conditioning requirements for a customer site. John Barnes Advisory Engineer Lexmark International s_douglas%ecrm@interlock.lexmark.com on 04/27/99 10:47:28 AM Please respond to s_douglas%ecrm@interlock.lexmark.com To: emc-pstc%majordomo.ieee@interlock.lexmark.com cc:(bcc: John Barnes/Lex/Lexmark) Subject: Heat Calculation Hello, Does anyone know how to compute heat dissipation for a product given mains power input (volts, amps, watts)? Our spec sheets always list heat dissipation (e.g. 1,000 BTU/hour) for each product and I wonder where the number comes from and why it never changes from one product to the next. Thanks for any comments received. Scott s_doug...@ecrm.com - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: IEC 950 Insulation Requirements
Donald, The numeric suffixes key Table 0.1 to Figure 5A: * OP1 through OP6 are all OPERATIONAL INSULATION (clause 1.2.9.1) which does not provide protection from electric shock. * B1 through B8 are all BASIC INSULATION (clause 1.2.9.2) which provides one level of protection from electric shock. * S1 and S2 are both SUPPLEMENTARY INSULATION (clause 1.2.9.3) which provides a second level of protection from electric shock. * R1 through R4 are all REINFORCED INSULATION (clause 1.2.9.5), which is equivalent to DOUBLE INSULATION (clause 1.2.9.4), which consists of BASIC plus SUPPLEMENTARY INSULATION. * S/R is SUPPLEMENTARY or REINFORCED INSULATION that meets Table 0.1 notes 3 4. The insulation requirements cover not only the expected peak voltages, but also the transient voltages that may appear on the different circuits. They also cover the possibility of a pinhole or insufficient overlap of the insulation permitting an arc to occur. Insulation requirements are mainly covered by IEC 950: * Section 2.9 Clearances, creepage distances and distances through insulation. * Section 5.3 Electric strength. * Section 5.4 Abnormal operating and fault conditions. * Annex F (normative) Measurement of creepage distances and clearances. Clearance is distance through the air. If an arc occurs, and then stops, the air is assumed to completely return to normal. Creepage is distance over the surface of an insulator. If an arc occurs and then stops there can be damage that leaves the surface conductive or otherwise more prone to arc again. The required creepage distances are a function of: * Transient voltages. * Pollution class-- how much crud can build up on a surface its likelihood of getting wet. * Comparative Tracking Index (CTI)-- how badly insulator gets damaged by an arc. John Barnes Advisory Engineer Lexmark International donald%hq.rossvideo@interlock.lexmark.com on 04/12/99 11:11:56 AM Please respond to donald%hq.rossvideo@interlock.lexmark.com To: emc-pstc%majordomo.ieee@interlock.lexmark.com cc:(bcc: John Barnes/Lex/Lexmark) Subject: IEC 950 Insulation Requirements I have just received a copy of the IEC 950 standard and after reviewing the insulation requirements outlined in section 2.2.6 I have a question that the group maybe able to shed some light on. The question relates to the two table 0.1 and Table 5 which is intended to give examples for the application of the various insulation requirements. In the two table it appears there are numerical reference to the different categories of insulation, for example OP1, OP2, B1, B2 etc. I have reviewed the entire standard and I can not find any other reference other then these tables to these numerical references of the different categories of insulation. Could some one provide some insight in the the intent and use of these tables? Are the numerical references simply to identify various circuits to circuit situations and which of the five categories of insulation applies? Thanks before hand Donald McElheran Product Engineering Ross Video Ltd. - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: HAR Cordage - Who needs it?
Ron, As a product developer, my major concern was getting the Lexmark Marknet XLe approved worldwide. From my viewpoint HAR approval of the jumper cord was equivalent to a bunch of individual country approvals. But Feller is still the only manufacturer that I know of that makes IEC-320 jumper cords with all the European approvals and UL/CSA-listing, and they chose to go for HAR approval on the cordage. We had just a little more trouble than normal getting UL, CSA, European, and Nordic approvals of the Marknet XLe's, mainly from having a Class 1 grounded auxiliary output on an internally Class 2 double-insulated product . We sold many 10's of thousands of Marknet XLe's worldwide until they were replaced by the Lexmark Marknet Pro's, and I have yet to hear of a complaint from a customer about the jumper cord. John Barnes Advisory Engineer Lexmark International - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: US/ HAR line Cord
Rich, UL does not accept HAR cordage in the USA because the HAR cordage does not meet the UL/ANSI standards for cordage. Likewise UL/ANSI cordage does not meet HAR requirements. Cordage that is Harmonized and UL/CSA-listed is rare but not impossible to find. Feller offers these Universal cordage styles: * HARSVT, 2x18AWG * HARSJT, 2x18AWG * HARSJT, 2x16AWG * HARSVT, 3x18AWG * HARSJT, 3x18AWG * HARSJT, 3x16AWG * HARSJT, 3x14AWG For the Lexmark Marknet XLe External Printer Servers we used a 10-foot jumper cord made of Feller's HARSVT, 3x18AWG cordage with molded-on IEC-320 C13 and IEC-320 C14 connectors. The XLe had worldwide approvals, and we marketed it worldwide with just the one jumper cord. The power supply for our Marknet Pro External Print Servers uses a similar 3x16AWG cordage. This power supply has been approved by UL, CSA, SAA, MITI, FIMKO, and SEMKO, with the cordage made by YEH YANG and LU CHIANG. John Barnes Advisory Engineer Lexmark International - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: AC Adapters
1. Is it true that plug adapters similar to those used by tourist are not legal in most countries? Back in 1991, when we were still part of IBM, I looked at getting a power supply that would have an attached linecord with a CEE7 XVI(2) Europlug plug on it for Europe. For the United Kingdom and other countries that use the BS 1363 plug I wanted to use a plug adapter like you describe. Our Product Safety folks looked into it for me, and after a couple of weeks said that they could not see any way to get BSI approval of such an adapter for a permanently-installed piece of equipment. So we wound up putting an IEC-320 appliance inlet on the power supply and using standard linecords. I have not run across anything since then to indicate that plug adapters are legal for anything except temporary use. For the Lexmark Marknet XLe External Print Servers we got around the need to ship with nine different linecords by putting an Appliance Inlet/Outlet on the XLe's power supply and shipping a jumper cord with the unit. This IEC-320 C13 to IEC-320 C14 jumper cord had UL, CSA, and HAR (European Harmonized) approvals so it was accepted worldwide. The customer would steal the linecord from a nearby printer and plug it into the XLe's appliance inlet, then plug the jumper cord into the XLe's appliance outlet and the printer's appliance inlet to provide power to the printer. The Appliance Outlet plus jumper cord cost us about $4.50 in large volumes. For the Lexmark Marknet Pro External Print Servers we now have a universal power supply with a Y-cable. The Y-cable has an IEC-320 C13 female plug on one end and an IEC-320 C14 shrouded-male connector on the other end, with the power supply picking off its power at the junction of the two cables. The Y-cable serves the same function as the Appliance Outlet-jumper cord do for the XLe. This is a much less expensive solution, but took almost a year to get through all the safety agencies. 2. How many different adapters are required to be stocked to handle the various requirements for plugs and safety approvals? We find that nine grounded-plug styles cover us worldwide: * UL 817.21 (NEMA WD-1 5-15P, US and Canada). * AS 3112 (Australia). * BS 1363 (United Kingdom). * CEE7 VII (Schuko, Europe). * SII-32 (Israel). * SEV 1011 (Switzerland). * SABS 164 (South Africa). * CEI 23-16 (Italy). * AFSNIT 107 (Denmark). For a 2-wire (double-insulated, Class 2) product the CEE7 XVI(2) Europlug could take the place of the CEE7 VII and SEV 1011 plugs. 3. Would you please identify them by the countries that use them? Or, is there a good on-line source for this information? I believe that the most authoritative information on AC power to be found online is Panel Components Corporations' http://www.panelcomponents.com/guide/guide.htm They also have a free catalog, Export Designer's Reference Catalog #9, which is a superb reference for anyone concerned with worldwide power requirements (plus they offer some very fine products). You can get a catalog by calling them at (800)662-2290 or (515)673-5000, or E-mailing them at i...@panelcomponents.com. Some other websites with international primary-power-voltages/frequencies/plugs are: * http://kropla.com/electric.htm * http://www.walkabouttravelgear.com/wwelect.htm * http://www.fele.com/empd/tech/fe-power.html * http://www.thomasregister.com/olc/interconfig/ * http://www.thomasregister.com/olc/interconfig/icipg4.htm * http://www.thomasregister.com/olc/interconfig/icipg5.htm * http://www.quail.com/intcords/ * http://www.quail.com/locator/index.html * http://www.computerac.com/IPC.html * http://www.teleadapt.com/web/Catalogue/Index John Barnes Advisory Engineer Lexmark International - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
