Re: Bad Fuse vs. Good Fuse
Doug, The ony experience I ever had with bad fuses blowing prematurely was a soldered-in picofuse laying across a heavy copper trace on a PCB. This trace was retaining enough heat after soldering to weaken the fuse, causing premature failure in the field. Raising the body of the fuse off the board solved the problem. Incidently, the problem was caught early through statistical analysis of field returns. Scott Lacey P.S.: It is well known in the automotive field that the old glass tube fuses often failed prematurely due to repeated stress and vibration. The newer blade type fuses are far more reliable. On 23 May 2003 at 16:56, POWELL, DOUG wrote: Hello all, Recently, in my company, we've been discussing what exactly constitutes a good or bad fuse. In this industry we often hear that the trouble with a defective product was, the fuse was bad. I occurred to me that the fuse is not bad, it performed exactly intended. In fact if the problem that caused the fuse to operate is still present, then the fuse is still good even though it is now an open circuit. The only time it can be a bad fuse is if it did not operate, resulting in shock or a fire. I have now have my ears tuned-in to this concept of a bad fuse and find it is commonly used all over the industry. In fact you can go to any number of websites that provide trouble shooting notes, and find instructions on how you can measure a bad fuse from a good fuse using an Ohm meter, photos included. And some of these instructions are from reputable manufacturers. Another term often used is defective fuse, which in some way sounds more scientific, but is still fundamentally wrong. I recently saw a newspaper article that gave the explaination why electrical service was lost for over 100,000 people as a bad fuse. An investigation was under way to determine why the fuse went bad. This is a little like hearing the technologically uninitiated say it must be a short somewhere, when the television set stops working. Maybe I am finicky, but this affects how companies view real product defects. When the defect is the bad fuse, then the real problem may be covered up. Often the answer is, increase the fuse size to prevent nuisance trips. The risk, of course, is that for every incremental increase in fuse value, you increase the risk of fire proportionally. Any thoughts or experiences? BTW - To all US citizens in the group, have a relaxing Memorial Day weekend. -doug Douglas E. Powell Regulatory Compliance Engineer Advanced Energy Industries, Inc. Fort Collins, CO 80535 USA ___ This message, including any attachments, may contain information that is confidential and proprietary information of Advanced Energy Industries, Inc. The dissemination, distribution, use or copying of this message or any of its attachments is strictly prohibited without the express written consent of Advanced Energy Industries, Inc. This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: Heat Sink Colour.
As a general rule of thumb, use polished aluminum fins (no finish) for high velocity forced air cooling (maximum thermal transfer to the airstream). Black anodized works well with more gentle airflow, and you would want a rough cast or sandblasted blackened finish when relying solely on natural convection. The rough surface increases both surface area and turbulence. scott Lacey On 9 May 2003 at 9:50, LEUNG YAT WAH DEREK wrote: Could anyone tell me about the heatsink is really in lighter colour can release heat faster ( similar to we wearing lighter clothes in summer), but why people always painted the heatsink in black or very dark colour, and the material of the coating on heatsink will affect their performance? Thanks. --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: Changes to IEEE emc-pstc web-based services
John has succinctly summed up the situation that many of us find ourselves in. It is a shame that the internet community is being divided into the haves and havenots (broadband vs. dial up). I for one refuse to be forced to upgrade to broadband from my very satisfactory $7.50/month current internet account. As one who has had an email address (and Unix shell account) back in the days before most people ever even HEARD of the internet, I am saddened by the current trend towards massively increased content that is wiping out much of the benefits gained from better and faster hardware. I still use the ALT functions in web pages I write to insure that they are lynx friendly. Scott Lacey On 1 Jan 2003 at 9:00, John Woodgate wrote: It seems to me that the web site system is OK for people with 'always- on' connection, but for those of us on dial- up, especially pay-as-you-go dial up, it will be too expensive to justify participation. -- Regards, John Woodgate, OOO This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
Re: High Voltage Relay HELP!!!
Brian, There are a couple of things that you might try: 1) Modify your PCB outline to rout a channel between the contacts and coil. This would have to be cut completely through the PCB board, so any internal planes would need to have clearance added first. I have seen this done successfully with opto-isolators that did not meet creepage spacings. 2) Use a high-voltage epoxy compound to add insulation around the relay pins. This reduces the potential at the PCB surface. It would have to be added post-solder. Another less pleasant option is to add extension leads to the relay, insulate with high- voltage epoxy, and then bend the exposed portion of the leads to match the PCB holes which would have the correct spacing. The main advantage over method 2 is the ease of replacing the relay (no epoxy on the PCB). I would ask the relay vendors for advice. You cannot be the first customer to have encountered this issue. Scott Lacey On 10 Dec 2002 at 15:33, brian_ku...@leco.com wrote: Happy Holidays Group, Let me set the scene for you: We have a piece of laboratory equipment that has a 10,000 volt low current power supply that puts a high potential onto a small metal sample as it is being tested. When the operator opens a door to remove the sample we have to turn off the high voltage to protect the operator. We have been looking for a High Voltage Relay to do the job without luck. We have found several that are rated for 10,000 volts, but the creepage and clearance spacing between the pins don't seem to match what the IEC61010-1:2001 standard says. If I am reading the standard correctly, the creepage is the big problem. Table 7 calls for a spacing of 40mm on pc cards pollution degree 1. This seems like a lot. The clearance would be 30.3mm - 31.6mm according to Table 5. We have one relay that is rated 10,000 volts, but it only has 23mm between the contact and the coil pins. How can this be? Am I looking at something wrong here? I can't find any high voltage relays with any kind of agency approvals. 1. Am I figuring out the creepage distance correctly or am I missing something? 2. If I do have to meet the spacings listed above, does anyone know of a good source for a compliant relay? 3. Anyone have tips and suggestions how to minimize spacings in high voltage circuits? Thanks to all. Brian Kunde LECO Corp. --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
Size of recent postings
To the group, Recently there have been several rather large (50k plus) postings to this forum. I would like to remind fellow listmembers that many people do not have high speed connections to the internet. Large files can seriously slow down retrieval of email on a dial-up connection. Please consider posting a summary with an invitation to send the larger files to interested parties. Thank You Scott Lacey --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: David Sproul...UL creepage limits ;~)
I thought that I might weigh in on this one: As someone mentioned previously, the big hazard involved in jump starting an automobile is the risk of a spark igniting hydrogen gas vapors from the battery. This causes the battery to explode, which sends dilute sulfuric acid and pieces of the battery case flying everywhere. A local service garage still has holes in the plaster ceiling from one such event. Whenever working around an automobile battery EYE PROTECTION SHOULD BE WORN! Many service centers now require technicians to wear full face shields around batteries. Service manuals advise connecting positive leads first, and then making the final negative connection (at the jumped vehicle) to a good ground AWAY from the battery. Any heavy bracket bolted to the engine should do. This is the last connection made and the first to be removed. There is always some sparking when jumping a battery and the idea is to keep it away from those vapors. There is a second hazard with modern vehicles. Suddenly breaking the connection may cause the voltage to spike which can damage electronics. This is because solid- state regulators have a much faster loop response than the older mechanical ones, especially when mounted on the alternator. A wise precaution is to place some loads such as headlamps on high beam before removing the jumper cables. I have done it this way many times without problems. The sulfuric acid in batteries is dilute enough that getting splashed will not cause immediate harm EXCEPT TO THE EYES. When gotten on the skin the first symptom is an itching sensation that quickly gets worse. The skin starts to redden as it begins to hurt. Rinsing with water will prevent injury. Any water, even from a mud puddle, is better than letting the acid remain. Even spit may be resorted to if nothing else is available. Creepage does exist around automobile batteries. There are three major sources: 1) Intentional low current circuits such as clocks, etc. These draw some current even when the vehicle is not running. 2) Dirt and conductive salts on the battery case. If not cleaned periodically they can drain a battery over time. 3) Faulty wiring or defective circuitry. These can cause huge current drains and may be the cause of some accidents when jump starting a vehicle. I always like to connect a test light in series with the last connection when the cause of the dead battery is unknown. If it glows brightly the load is too severe to take the risk. I apologize for being so wordy but I hope that sharing my experience may save fellow listmembers from vehicle damage or serious injury. Scott Lacey ORIGINAL MESSAGE This is because when you double the voltage the power is proportional to a quarter of the current Very high voltage circuits hardly creep at all whereas low voltages creep the most. That is why you should never join the two negative terminals when you jump start a car, the car battery charging circuits have so much creepage they can melt the battery. I though everybody knew that... --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
Re: information safe
Lucian, While from a theoretical point this could work, legal considerations might hinder the use of such a system. It used to be a common audio trick to use an amplified white noise (broadband) source to disable hidden eavesdropping microphones. The noise was almost impossible to filter out without also filtering out the voices. An RF noise bridge in an unbalanced condition feeding an RF amplifier connected to a broadband antenna would probably work, but would not be legal. It might also raise havoc with the PC. A friend used to work for a foreign pharmaceutical company. They used a particular brand of laptop computer (I've forgotten which) that had a very low emi signature. They assumed that their competitors would spy on them to gain an edge in that ultra competitive business. Scott Lacey On 3 Oct 2002 at 20:26, Lucian wrote: Dear Sirs, We know it's very important to keep information safe, while PC and its monitor emit signals always. One method to deal with it is shielding, another method is to place an emitter besides PC emitting signals to interfere with PC's signals. Does anybody know anyinformation about the latter method? Thanks a lot in advance. Best regards, Lucian --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
Re: Nema 5-15R sockets
Art and JIm, One other thing to note: All of the flat (air conditioner type) heavy- duty cords and extensions I've seen that fit this type socket seem to be designed for use with the ground pin at the bottom. Also, although there is some shock hazard from the partially retracted Hot lead with the ground at bottom, when an outlet is installed with the ground pin up it is possible to have the ground lead disconnect first. If this happens with a product with high (but acceptable) leakage a potentially lethal situation exists. Scott Lacey On 19 Jul 2002 at 13:59, Art Michael wrote: Hello Jim, I don't believe the orientation of the U-ground pin is declared anyplace in the NEC. When I recently approached my local AHJ with this question he related that it is a matter of custom (locality dependent). In this area, central Connecticut, the custom is: For commercial/industrial applications, U-Ground topmost For household wiring, U-Ground towards the bottom The rationale offered for the U-Ground topmost; if the plug partially separates from the outlet, anything falling into the opening between the plug and the outlet will first encounter the grounding pin. (seems to me that argument holds whether the use is commercial/industrial or household). Re dimensions of the outlet; send me your fax # and I'll fax you the dimensions. Regards, Art Michael -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- |http://www.safetylink.com | | | | The Safety Link is the most comprehensive collection | |of product safety and standards links on the WEB| |Check our latest offer. | | | | | | Int'l Product Safety News | | Founded in 1988 | | | | P.O.Box 1561 - WWW | |Middletown CT 06457-8061 U.S.A. | | Phone: (860) 344-1651 Fax: (860) 346-9066 | | email: i...@safetylink.com | -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --- On Fri, 19 Jul 2002, Jim Eichner wrote: A couple of questions about our standard North American 120Vac socket: 1. Orientation: We have lots of people in the office here on both sides of this one, and I can't find a normative reference in the CEC or the NEC. Which is the correct way up when installing a socket on a wall - ground pin above the L and N blades, or L and N above the ground? What is the code reference for this requirement, or is there none? 2. Dimensions: Can anybody share the spec's for the dimensions, with tolerances, of the line, neutral, and ground blades for this configuration? I'm sure it's in the UL and CSA standards but I don't want to spend hundreds of $ for a one-time question. We have no on-going need for these standards! Thanks in advance for your help, Regards, Jim Eichner, P.Eng. Manager, Engineering Services Xantrex Technology Inc. Mobile Power web: www.xantrex.com http://www.xantrex.com Any opinions expressed are accidental. I have none. Confidentiality Notice: This email message, including any attachments, is for the sole use of the intended recipient(s) and may contain confidential and privileged information. Any unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message. --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line
Lightning Protection for PA System
To the group, I am seeking advice as to the best methods of protecting a Public Address system against recurring lightning damage. The system uses several commercial PA amplifiers, each driving several speakers at indoor and outdoor locations. There are also several locations where microphones can be plugged in. The longest speaker wires may be up to 250 yards long. It is believed that the charge is being coupled to the speaker wires where it then returns to ground at the amplifier location within the building, destroying the solid state devices within the amplifier. A technician has added fuses to all external microphone inputs and speaker outputs. While these have blown several times during storms without obvious damage to the amplifiers it is my belief that fuses are generally too slow to protect semiconductor devices. I am seeking advice as to surge suppression devices. System particulars are as follows: 1) The PA amplifiers have 70 volt outputs. All speakers are transformer coupled. 2) All microphones use standard XLR connectors. They plug into metallic conduit mounted jacks at locations inside and outside the building. The outside microphones are unplugged during storms. 3) The amplifiers are located on the second floor of the building. Each amplifier is dedicated to a set of speakers at one location. The amplifier driving the longest wires is the one which most often has to be replaced. 4) The building is in a location known to be susceptible to lightning activity. Electrical appliances have been destroyed on at least two occasions. 5) All protective grounding efforts to date have been made to the conduit. I am recommending that this be supplemented by driven rods. It is pretty easy to buy commercial surge suppression devices for the ac lines. I feel I need advice as to the best methods to protect the audio inputs and outputs. For the 70 volt outputs I am thinking of using gas tubes to earth where the wires enter the building supplemented by MOV, Tranzorb, or other devices near the amplifier location. I welcome suggestions as to device types. For the microphone inputs I am thinking of using semiconductor transient voltage suppressors near the amplifier. Again, any suggestions are welcome. Thanks in advance for any advice and guidance. Scott Lacey sco...@world.std.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: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
Re: 1kW per square meter.......free
Ted, While most alternative energy schemes sound very promising, energy efficiency problems make most of them impractical for real world use. Small solar charging systems are great for maintaining a charge on a seldom used battery in a spare automobile, or similar application, but the ratio of charge time to usage has to be large. The problems with a solar powered automobile would be: 1) Lots of expensive (and unsightly) solar panels plus the numerous serial and parallel connections needed to make a usable system. Even then, the car would have to be parked in the sunlight many more hours than it was driven. 2) An expensive buck/boost charge controller to compensate for the enormous voltage variations due to weather. 3) A trunk full of heavy, expensive batteries, with their need to be eventually replaced. 4) And finally, how would the batteries be charged if it rained for four or five days straight? The hybrid gas/electric vehicles seem to be the only practical electric vehicles made so far. And even these seem to be expensive enough that sales have to be subsidized. I know people who have tried to use solar dc electrical systems at remote camps. You have to strictly ration electrical usage even if you only use the place on weekends after it has charged all week. Most people eventually revert to using combinations of propane, gasoline, and kerosene for light and cooking. A gallon of Coleman fuel will last a week running a stove and some lights. As to the energy efficiency of gasoline, years ago I watched a demonstration where a homemade mortar lobbed a sand-filled beer can hundreds of yards using a SPOONFUL of gasoline! It graphically proved the point about why it is so hard to replace the internal combution engine. Scott Lacey On 7 Jun 2002 at 13:52, Ted Rook wrote: sorry, off topic, mostly for US residents: just imagine everyone's car being coated with 'solar cell generator' material with a storage device in the trunk.. and how about air-conditioners that run on the Stirling cycle from a solar energy collector... lousy for the oil lobby but fantastic for the human race --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: Coaxial Switches - use with spectrum analyzer and gear?
Timothy, I'm somewhat sceptical that kovar (nickel/cobalt/iron) would be used for relay contacts. In my experience better quality relays and switches use coin silver or similar for contacts due to it's low resistance. Only the plunger of the relay needs to be of ferrous metal. As to the original question I see no reason why high-quality coaxial switches could not be used as long as they were periodically checked (characterized) the same as all cables and other pieces should be when used for serious work. Scott Lacey On 24 May 2002 at 15:52, Christman, Timothy (STP) wrote: This may not be the effect being referred to, but... Relays require a ferromagnetic alloy, such as Kovar for the contacts. The leads leading to the connector are more likely beryllium copper or some similar material. The weld or joint between them forms a thermoelectrically active junction, and an associated error potential. Ideally, the two contacts form two sets of junctions that are opposite in polarity. In reality, they are seldom identically constructed, and if there's a temperature gradient across the part the error is magnified. Perhaps this was an effort to stress that the signal amplitude should be in excess of the thermoelectric offsets. Another possibility -- Many small form-factor relays are the reed type, so wiping action across the contacts forms a conduction path. There may be a minute oxide layer there or elsewhere in the system which will create the non-linear behavior described. Point contact rectification and dielectric breakdown become possibilities. Probably not pertinent, but interesting. Timothy J. Christman Test Engineer Tel 651.582.3141 Fax 651.582.7599 timothy.christ...@guidant.com Guidant Corporation 4100 Hamline Ave. N. St. Paul, MN 55112 USA www.guidant.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: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
Re: Surplus EMC Test Equipment available
Michael, I fail to see why anyone should be wrathful about a onetime offering of equipment directly related to the work performed by list members. Not all of us work for corporations with deep pockets (and some of THOSE aren't so deep lately) so used equipment is often the only choice available. I view the listing of surplus emc/safety test equipment the same as listing of available emc positions - it is a service to list members. On another subject, and not referring to any particular posting, the tone of some responses have been a little bit edgey lately. I urge all listmembers to consider that a posting that annoys them today may be from someone who has provided help in the past. Let's please all extend professional courtesy to our colleagues and try to avoid divisiveness, or else change the rules to encourage flaming so that we can form alliances and get to (grin) vote someone off the island. Wishing all a relaxing and restful weekend, Scott Lacey On 15 May 2002 at 16:59, Michael Taylor wrote: Greetings all. Risking the wrath of some list members, I am posting a list of surplus EMC test equipment. I hope no one takes this as a business offering, which it is not. I would prefer these items to go to a working lab instead of just being sold off to a broker. The recent assimilation of another company into the Danaher Corp. Collective has resulted in several EMC Test equipment items declared surplus. These items are all in like new condition and guaranteed working to spec. If anyone has any interest in these items please contact me off-line. No reasonable offer refused. Below is a list of items. (with the understanding the list is preliminary and may change subject to upper management decisions over which I have no control) Items 1 2 are available now. Items 3-14 will not be available for 30-35 days. (I was directed to list them now) Thank you for your understanding in this listing. Michael Taylor Colorado mtay...@hach.com 970-663-1377 ext 2646 items available now 1. Lindgren shield room (2 years old) 16' L x 12' W x 10' H w/ 4' door (unlined), 2x 30A filters two 12 wave guide air vents. Buyer responsible for disassembly removal prior to 7/30/02. Located in Wisconsin. 2. TEM Cell, Voltek G-STRIP 4'x4'x4' in good condition. the following are scheduled for surplus in the next 30 days. 3. Schaffner NSG 1025 EFT/Surge Generator w/ 2 CDN's 4. Schaffner CDN-125 EFT Coupling Clamp 5. EMCO 20A LISN 6. SOLAR 24A LISN 7. Chase MA2050B LISN 8. KeyTek Mini-Zap ESD gun (complete kit) 9. Advantest 3 Ghz Spectrum analyzer 10. HP L1500 / 4401A 1.5 Ghz Spectrum Analyzer 11. HP 7 series System Spectrum Analyzer (a great system EMC Analyzer for an automated test system) w/ 70206A Graphics Display unit 70001A Mainframe 70300A Tracking Gen. 70621A Preamp (10Hz-3 Ghz) 70904A RF Section 70400A Local Osc. 70902A IF (10Hz-300Khz) 70903A IF (100Khz-3Mhz) 12. HP 8648A Signal Gen. (9K-1Ghz) 13. Marconi Signal Gen. 2022E (9K-1Ghz) 14. Elgar, SW-5250 Programmable AC Power Source, 40Hz-400Hz 3phase @1750VA/phase (can be ganged for 18A -1 phase @ 366V) for harmonics, flicker, Power Qual. 15 Fischer Communications, model BCICF-1, Injection Clamp Calibration Fixture. end of list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: High Temp Caps and Inductors
Derek, You might try Texas Components (www.texascomponents.com) for high temperature capacitors. They claim usage up to 200 C. I suspect you will have to build (or have built) the inductors. You might check with Dupont to see if Kapton (a high-temperature polyamide) would be suitable for cores. You will also need to obtain magnet wire with suitable insulation, and I suspect that you will have to either weld or silver solder the interconnections. Once you have determined the materials choices any good custom magnetics house should be able to produce the inductors in quantity if needed. Good Luck, Scott Lacey -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of lfresea...@aol.com Sent: Friday, April 19, 2002 5:19 PM To: emc-p...@majordomo.ieee.org Subject: High Temp Caps and Inductors Hi all, I'm designing a filter that has to live and work with an Ambient temp of 180 C. Does anyone have suggestions as to component vendors that I could contact for parts? Thanks, Derek Walton. L F Research
RE: Pencil erasers for pre-EMI cleaning? (cleaning mating surface s, chassis, )
Robert, The North American paper sizes are not irrational, just dated. The engineering sizes (A through D) were originally mainly used with the contact diazo (blueprint) duplicating method. The copies are all at 1:1 ratio with the original drawing, which was hand drawn in the days before CAD. Enlarging/reducing had to be done with a very large and expensive process camera. This was usually only done to make offset printing plates for manuals. The selection of sizes was actually very rational, as all the larger sizes can be neatly folded to A size (8 1/2 X 11) with the title block showing on top. As for the U.S. Patent Office, I believe the switch to the metric paper was done at the same time the patent period was changed (along with other details) to harmonize with other nations under international patent agreements. Finally, the side issue of discussing paper sizes resulted after it was mentioned that the downloaded galvanic compatibility chart could not be printed on 8 1/2 X 11 paper. If the host based printer driver is loaded it is possible to scale printed output to any size desired. The hardware based print drivers generally do not have this ability. Scott Lacey -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Robert Wilson Sent: Tuesday, March 05, 2002 11:47 AM To: emc-p...@majordomo.ieee.org Subject: RE: Pencil erasers for pre-EMI cleaning? (cleaning mating surface s, chassis, ) More importantly, North American paper sizes are just plain irrational. At least the metric sizes all have the same aspect ratio, so enlarging/reducing from one size to another doesn't result in a large band of unused space. Even the US Patent Office has given up on US A (8-12 x 11) or US legal (8-1/2 x 14) size, and for at least 10 years, submissions have to be made on the metric A4 size paper that most of the civilized world uses. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: John Shinn [mailto:john.sh...@sanmina-sci.com] Sent: March 4, 2002 4:18 PM To: 'John Woodgate'; emc-p...@majordomo.ieee.org Subject: RE: Pencil erasers for pre-EMI cleaning? (cleaning mating surface s, chassis, ) Actually, US Legal size is 8-1/2 by 14 inches. 8-1/2 by 17 inches is B-size. John Shinn, P.E. -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of John Woodgate Sent: Monday, March 04, 2002 11:36 AM To: emc-p...@majordomo.ieee.org Subject: Pencil erasers for pre-EMI cleaning? (cleaning mating surface s, chassis, ) I read in !emc-pstc that david_ster...@ademco.com wrote (in 2DF7C54A75B dd311b61700508b64231002c5a...@nyhqex1.ademcohq.com) about 'Pencil erasers for pre-EMI cleaning? (cleaning mating surface s, chassis, )', on Mon, 4 Mar 2002: It prints on legal (8-1/2 x 17) paper. That size is 'illegal' in Europe! (;-) -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Interested in professional sound reinforcement and distribution? Then go to http://www.isce.org.uk PLEASE do NOT copy news posts to me by E-MAIL! --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@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://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@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://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc
RE: Pencil erasers for pre-EMI cleaning?
David, Forget the pencil eraser. This is the same deal as using one to clean battery contacts. Works great - for a short time. Look on the web for Caig Laboratories, Inc. they make a series of chemicals that are meant to deoxidize metal contacts. I've used their DeoxIT D5 for years. I call it gremlin spray because it gets rid of pesky intermittent connections. Scott Lacey -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of David Heald Sent: Thursday, February 28, 2002 2:44 PM To: emc-p...@majordomo.ieee.org Subject: Pencil erasers for pre-EMI cleaning? All, I'm preparing for an emissions test and I had started cleaning some of my chassis mating surfaces with a pen/pencil eraser then alcohol to ensure the surface to surface contact was good. A friend then told me that using an eraser would also remove the anti-corrosive coating that was on the metal (Thanks Paul!). So I would end up with a very short term benefit, then rust. What I am trying to determine is if maybe light rubbing with a pencil eraser might only remove surface contaminants and leave the metal and coatings intact. (the pencil eraser is much less abrasive than the pen side) So the real question is... Does anyone have direct good or bad experience with the aftereffects of using a pencil eraser to clean mating edges (card faceplates in a telco box for example)? I have both steel and aluminum surfaces to worry about so info for either type is welcome. (and don't worry the different metal types are not adjacent). Any feedback would be greatly appreciated as the system is really dirty right now. Thanks and Best Regards, Dave Heald --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@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://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@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://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: Using PCB traces as transient voltage suppressor
Gabi, In my experience these crude spark gaps do work - for a while. The tips of the triangles tend to erode during surge testing, thereby raising the voltage required to jump the gap. I like the fact that you are only thinking of them as an addition rather than as primary protection. There are several drawbacks to be noted. 1) As already mentioned, the pads are fragile and erode with actual usage. 2) The discharge voltage is somewhat unpredictable and varies with dust, humidity, etc. 3) An audible snap is heard whenever a spark jumps across the gap. This may be unnerving to a customer who hears this. It may be perceived as a component failure. If cost allows I would recommend using a gas-filled discharge device instead. These are very predictable and repeatable, degrade much more slowly, and are much quieter. Scott Lacey -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Gabi Hoffknecht Sent: Wednesday, February 20, 2002 11:33 AM To: emc-p...@majordomo.ieee.org Subject: Using PCB traces as transient voltage suppressor Hi all, I have seen PCB designs with two triangular shaped copper pads pointed towards each other at very close proximity, meant as an air gap discharge path for transients. Does anyone have information about such designs, whether they work and how well ? At a breakdown voltage for air of 1 Megavolt per meter, they should theoretically work: 10mil distance would have a breakdown voltage of only 254V. Such a PCB design basically comes for free, so I was thinking of adding it on top of my already existing series impedance - TVS network. Thanks in advance for your comments. Best regards, Gabi Hoffknecht --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@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://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@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://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: Zero Crossing Question
Zero Crossing QuestionJohn, I think you already have the answer to the problem. You stated that Harris or Intersil IC's work properly regardless of the mains polarity. Some years back I had an issue where another manufacturer's replacement was substituted for a Sprague ULN2003 Darlington Array that I had specified in a design. I was using the ULN2003 to buffer a reset pulse distributed in a system. The other brand was not capable of switching quickly enough in this application. Replacing the ICs with the specified part solved the problem. I would not waste valuable engineering time resolving an issue that only occurs with one vendor's part. Just one man's opinion, Scott Lacey Simplicate, don't complicate! -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Bouse, John Sent: Monday, January 21, 2002 9:20 AM To: emc-p...@majordomo.ieee.org Subject: Zero Crossing Question Hi Group, Our manufacturing personnel encountered a strange problem: when the mains plug used on a 230V/50Hz equipment that has an internal zero crossing reference integrated circuit (specifically, a CA3059) is reversed (this can occur in countries such as Germany, Italy, France and Switzerland), the zero crossing pulses appear with a 20 millisecond spacing, rather than the expected 10 millisecond spacing. Harris or Intersil IC's work properly regardless of the mains polarity. ON Semiconductor IC's appear to be polarity sensitive. They will produce the proper number of pulses with only one mains polarity. The incorrect spacing of these zero crossing pulses affects the normal operation of the equipment. Has anyone encountered and, hopefully, solved this problem? Regards, John Bouse PKI
RE: HiPot testing of DC mains powered products
Chris, In my opinion you should perform the test with the cable that you ship. Your explanation for the second scenario states exactly why this should be done. Scott Lacey -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Chris Maxwell Sent: Tuesday, November 06, 2001 10:36 AM To: EMC-PSTC Internet Forum Subject: HiPot testing of DC mains powered products Hi all, I have a question. I have a 48VDC powered product which will be hipot and ground continuity tested off of the production line in order to maintain agency certification. The product uses D-shaped three pin power connector. (Same size as a DB15, but has three large power pins instead of 15 signal pins). When we sell the unit, we pack it with an accessory kit which includes a 15' cable assembly terminated with the mate to the product's power connector. So, essentially, we sell the unit with a DC mains cable that we make. Now, where should the hipot test be performed? Should I make a test cable assembly for the hipot/ground bond tester which is terminated with the proper connector so that the tester can plug directly into the chassis? This would essentially test the chassis only. (because we would use this same test cable for every unit) Or Should I take each unit and connect the DC mains cable to be shipped with it, then apply the hipot/ground bond probes to the other end of the DC mains cable? This would test the entire system including the chassis and the cable. In my mind, this question comes up because we are making a custom mains cable for this DC product. It is different than AC products; because, with AC products, we can test the chassis by itself and assume that the mains cable is OK because we buy mains cables that have been previously hipot/ground bond tested by their manufacturers. Any words of wisdom? Thanks, Chris Maxwell | Design Engineer - Optical Division email chris.maxw...@nettest.com | dir +1 315 266 5128 | fax +1 315 797 8024 NetTest | 6 Rhoads Drive, Utica, NY 13502 | USA web www.nettest.com | tel +1 315 797 4449 | --- 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. --- 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: EMC test table construction plans
Doug, Wood is ok if you seal it properly to prevent absorbed moisture from causing inconsistancies from one test to the next. Most clear resins do not cause RF problems whereas the metallic pigments in paints often do. If you can, covering the top with laminate (Formica) increases durability and provides a low friction surface. The best design is to make a sturdy table using the following criteria: 4 X 4 or doubled 2 X 4 legs. Top of 2 layers of 3/4 plywood or particle board. Apron to support legs of at least 2 X 4 or 3/4 X 6 cross section. Pivoting top overlay of 3/4 plywood or particle board with a piece of 1 1/2 PVC pipe for a pivot. What you do is either cover the table surfaces (top bottom) with laminate or sand, seal (multiple coats) and sand again plus wax to allow easy rotation. Drill matching holes through the center of the 3/4 overlay and the tabletop for the stub (4 long or so) of pipe. glue the pipe flush with the top of the overlay (it will protrude from the bottom). You just drop the overlay with pipe onto/into the tabletop with hole. During testing the table is rotated (1/4 turn) manually between tests. If you doubt that laminate can provide a low friction bearing, try this test - turn one table upside down on top of an identical table, rotate the top table, and then try rotating the table with a coworker standing on it. If you find too much friction apply some automotive paste wax. Scott Lacey -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of POWELL, DOUG Sent: Thursday, November 01, 2001 12:38 PM To: EMC-PSTC (E-mail) Subject: EMC test table construction plans Hello all, I plan to construct my own insulated EMC test table for a 5 meter chamber. Seems simple enough to do and I could easily come up with something. I thought I might first ask for input from those of you in the discussion group who have experience or maybe even construction plans. Here are some features I want: 1) I will be testing products that weight up to 200 Lbs (91 kg). 2) I want to minimize metalic fastners. 3) I would like to make it a pivoting table (not motorized). 4) Height is 80 cm. 5) The surface should be replacable if it gets badly worn or scarred. I'm thinking of using hardboard. 6) Suggestions on length width? -doug --- Douglas E. Powell, Compliance Engineer Advanced Energy Industries, Inc. Mail stop: 203024 1626 Sharp Point Drive Ft. Collins, CO 80525 970.407.6410 (phone) 970-407.5410 (fax) mailto:doug.pow...@aei.com --- _ This message, including any attachments, may contain information that is confidential and proprietary information of Advanced Energy Industries, Inc. The dissemination, distribution, use or copying of this message or any of its attachments is strictly prohibited without the express written consent of Advanced Energy Industries, Inc. --- 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. --- 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: Fish paper
RE: Fish paperSorry guys, but, after monitoring this thread it would take a mackerel to keep me out of it. I can't bass up an opportunity to join in even if it seems crappie to some. Let's hear from some of those who just perch here walleye'm in the mood for it. Otherwise the rest of us will wind up in a pickerel. Scott Lacey -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of wo...@sensormatic.com Sent: Thursday, October 25, 2001 4:17 PM To: emc-p...@majordomo.ieee.org Subject: RE: Fish paper Let's hear from others. Don't be squidish or shellfish and clam up on us. Sorry, the devil made me do it. -Original Message- From: Whitehouse, Terence (Terry) [mailto:twhiteho...@avaya.com] Sent: Thursday, October 25, 2001 3:54 PM To: 'Dan Teninty'; lcr...@tuvam.com; emc-p...@majordomo.ieee.org Subject: RE: Fish paper What a great grouper we are. With snapper responses we don't flounder around because - like Marlin Deitrich - we have got lots of sole. This laughter therapy is recommended by the Sturgeon General; so let's not change our tuna - there must be lots more to come.! Terry W. -Original Message- From: Dan Teninty [mailto:dteni...@dtec-associates.com] Sent: Thursday, October 25, 2001 10:05 AM To: lcr...@tuvam.com; emc-p...@majordomo.ieee.org Subject: RE: Fish paper I smelt that coming :) Dan DTEC Associates LLC http://www.dtec-associates.com Streamlining the Compliance Process 5406 S. Glendora Drive Spokane, WA 99223 (509) 443-0215 (509) 443-0181 fax -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of lcr...@tuvam.com Sent: Thursday, October 25, 2001 6:36 AM To: emc-p...@majordomo.ieee.org Subject: RE: Fish paper I think you have Perch'ed your argument rather precariously. Walleye understand where you are coming from, Salmon is sure to disagree with you. Best reference the National Electrical Cod. ;-) Lauren Crane -Original Message- From: wmf...@aol.com [mailto:wmf...@aol.com] Sent: Thursday, October 25, 2001 7:04 AM To: emc-p...@majordomo.ieee.org Subject: RE: Fish paper Of course; after its namesake, fish paper could be expected to be hygroscopic. Or maybe someone just called it fish paper for the halibut. --- 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: skinny power cords.
Jim, It seems that some of the offshore manufactured cords are molded from melted Hershey bars! I am always very careful who I buy my cords from. Scott Lacey -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Jim Eichner Sent: Thursday, October 25, 2001 3:40 PM Cc: emc-p...@majordomo.ieee.org Subject: RE: skinny power cords. Thanks Rich: I suspect you're right. Isn't that mechanism exactly what the tracking index tests are meant to address? I thought that any UL-approved wiring device like this would have a material that is designed to resist tracking, hence my speculation that contamination might be involved. I guess there are a few more comments to be made here... 1. From what I know, the tracking index tests are horribly non-repeatable and are therefore somewhat meaningless. 2. The standards for plug caps and for multi-taps may not refer to UL746 and may not have any of their own requirements for tracking index of insulation. 3. We could take this as evidence that even compliance with the tracking index requirements doesn't prevent carbonization of the material where there's a high temperature heat source involved. There are lots of people who unplug anything they are not actively using. I guess it's not such a paranoid practice! Regards, Jim Eichner, P.Eng. Manager, Engineering Services Xantrex Technology Inc. Mobile Power web: www.xantrex.com http://www.xantrex.com Any opinions expressed are those of my invisible friend, who really exists. Honest. -Original Message- From: Rich Nute [mailto:ri...@sdd.hp.com] Sent: Thursday, October 25, 2001 12:14 PM To: jim.eich...@xantrex.com Cc: emc-p...@majordomo.ieee.org Subject: Re: skinny power cords. Hi Jim: I'm curious: given that North American plug blades are 1/2 apart, there must have been substantial contamination to aid in 120Vac jumping that far (arcing). Did you identify any sort of contamination or moisture? I don't believe contamination is a significant factor in events such as this one. I believe such events start with a loose connection between the plug and the socket (or between the wire and the socket parts). A loose connection means that the contact area is relatively small. In turn, this means high current density at the point of contact. The smaller the contact area, the greater the resistance of the contact. The smaller the contact area, the greater the current density at the point of contact. These two factors contribute to heating of the two parts, the plug blade and the socket. Heating tends to reduce the springiness of the socket part, and of the connection between the supply wire and the socket (because they are thermally connected). The heating also tends to degrade the surface of the insulating material in which the conductors are mounted. Heating also enhances oxidation of the plating on the parts, which further increases the resistance of the connections. If the plug-connected appliance is ON, arcing can occur as the parts expand due to heating and make various intermittant connections. Arc temperatures are very high, and can burn the surface of nearby insulating materials via radiation. As the surface degrades, leakages occur across the surfaces. At this point, whether or not the appliance is on or even connected is not a factor. There is a current path between the two poles along the surface of the insulator. This can either be between the socket parts, or between the wired parts. The leakage current causes further heating and micro-arcs where the leakage path opens due to current density. The micro-arcs further damage the insulator until there is nearly continuous micro-arcing. I suggest this is the source of the noise. The heat from the micro- arcing and the resistance of the carbonized surface of the insulator eventually lead to ignition and flames. I admit that this is a hypothesis. I believe that the process is more-or-less correct, but the details may not be correct. Best regards, Rich --- 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. --- This message is from the IEEE EMC Society Product Safety Technical
MIL-STD for crimped terminals on wires?
To the group, Hopefully someone can tell me number of the MIL-STD ocument for crimped connections on wires? Even better if they referenced the web site where the standard could be downloaded. Thanks in advance. Scott Lacey --- 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: high temperature circuit breaker
Gary, Kris, If these are indeed magnetic breakers, one point of caution should be advised. An ordinary magnetic breaker is very sensitive to high inrush currents from motors and transformers. They will often trip from these (normal) inrush currents. In such cases a motor rated version needs to be specified. They have additional damping to delay response time. Scott Lacey -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Gary McInturff Sent: Friday, October 19, 2001 1:36 PM To: 'kristiaan.carpent...@alcatel.be'; emc-p...@majordomo.ieee.org Subject: RE: high temperature circuit breaker Neither endorsing or rejecting these breakers I just happen to be doing a little research of my own and have a spec sheet open in front of me on these things. Square D has a Multi-9 series of breakers that shows an operating temperature of -30 to -70 C. and tropical treatment 2 for 95% rh of 95% at 55C. I haven't looked any further to see if they are Listed/Certified to those temperatures or if those are just the marketing numbers so you'll want to follow-up on that. They have a wider range of amperage ratings than the others I have quickly reviewed. I happen to be looking at a 2 amp breaker and typically those have only been Listed for Supplemental Protectors rather than Branch Circuit protection. You also want to consider whether they are thermal or magnetic breakers. If your worried about high temperatures you probably want to look at the magnetic breakers because they are less heat sensitive. Here is a link http://www.squared.com/us/products/circuit_breakers.nsf/unid/B7E8BB545346010 D85256AA30051A705/$file/multi9ul489breakersFrameset.htm Good luck Gary -Original Message- From: kristiaan.carpent...@alcatel.be [mailto:kristiaan.carpent...@alcatel.be] Sent: Friday, October 19, 2001 7:24 AM To: emc-p...@majordomo.ieee.org Subject: high temperature circuitbreaker Hello group, Circuit breakers and residual current operated circuitbreakers for house-hold applications are typically cetified at 40 degree Celcius. If these types are built into other products, they do not comply with their temperature rating as specified in the safety certificate. Does any-one know about references to circuit-breakers(230V ac, 10A) that can work safely at higher temperatures (70...90 degrees) Regards, Kris Carpentier --- 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. --- 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. --- 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: Motor Drive Grounding Scheme
Mark. As described, the situation to me sounds no worse than any other earthed connection. The only hazard would seem to be as a return for hazardous voltages - exactly the same situation as the sheet metal enclosure that surrounds it. In my experience sometimes the approver's representative makes a snap judgement when confronted with something unfamiliar. It then becomes difficult for them to back down without losing face. I would suggest gently trying to convince the representative of the logic of your position. Scott Lacey -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Mark Haynes Sent: Thursday, October 18, 2001 12:44 PM To: IEEE EMC-PSTC Discussion List (E-mail) Cc: Peter Deneault (E-mail); Tom Brenner; Doug Harris Subject: Motor Drive Grounding Scheme Greetings All, I work for a product safety consulting firm/test lab/agent. I am currently having some difficulties with UL relating to one of our customer's products. The grounding scheme of the products has become a barrier which has halted the planned testing. In our opinion, the engineering rationale behind this position is not very strong or clear. The products are small open-type stepper and servo motor drives (rated up to 6 A) which are intended to be used within another enclosure. They are powered by an 18 - 74 V dc external source which is supplied by the user. The drive output is a DC pulse width modulated waveform. UL 508C and UL 840 are the standards being used. The main issue is the fact that the DC - (common) input supply lead is connected internally to the input ground (PE) lead. UL has referenced UL 508C requirements (not really applicable to these particular products since we have agreed to use UL 840 for spacings) that indicate that spacings are required within the product between these two leads. This implies that this grounding scheme cannot be used. The manufacturer has indicated that the drives will not operate properly without this grounding connection. The product designers made this connection internally to prevent the common from floating above/below ground potential and for EMI purposes. The customer and my company do not agree with UL's position. One possible hazard UL stated was that the heatsink was connected to the grounded DC - (common) internal bus and could be electrically live. Since the heatsink is referenced to ground potential, it is not live during normal operation. If an internal fault does occur, the circuitry is designed such that the fault current will flow through the ground, as intended. In addition, a hint of possibly increasing the risk of shock was also mentioned. No one involved has been able to identify any real safety issues resulting from this grounding scheme. In order to address all potential safety hazards, we have recommended that testing be conducted to confirm compliance with the intent of the standards. This would hopefully show that the products are safe and that all foreseeable safety hazards (during normal and fault conditions) have been identified and minimized/eliminated. After weeks of research and discussions, we have not been able to convince UL that this grounding scheme should be allowed and that we should proceed with the testing. Does anyone know of any similar UL certified motor drives (or other similar DC powered products) that employ this grounding scheme? The closest examples we could find were AC powered products with DC ground referenced secondary circuits. However, this is not the same since a transformer usually provides the required isolation. Does anyone have any comments/information on this grounding scheme that might be helpful in building a stronger case either way? The closest thing we could reference was a grounded DC distribution system in the 1999 National Electrical Code (NEC - NFPA 70). Please respond at your earliest convenience. Thanks in advance for your assistance, Mark A. Haynes Senior Product Safety Engineer D.L.S. Conformity Assessment, Inc. 1250 Peterson Drive Wheeling, IL 60090-6454 (847) 537-6400 (Ext. 157) Fax (847) 537-6488 mhay...@dlsemc.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: No longer online until our new server is brought online and the old messages are imported into the new server
RE: EMI trouble shoot inquiry
Ouch! Having an interference source that is only a slightly longer wavelength than the RFID frequency is a real tough problem. If the bombarders are only interfering with transmits/receives and not actual writing false data to the pallet markers I would suggest altering the system programming to read the pallet while the bombarders are off, and then disable the RFID system during the bombardment process. If the transponders actually are having garbage written to them by the bombarders you need to contact OMRON for help. Scott Lacey -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of wmf...@aol.com Sent: Monday, October 15, 2001 2:43 PM To: emc-p...@ieee.org Cc: jim.gi...@hedus.com Subject: EMI trouble shoot inquiry Group: I attach an RF interference inquiry from a customer; I have no 'smarts' where RF ID is concerned, so I turn to this august body... ==paste==We have an OMRON RFID data transfer system operating within the same room as 12 RF generators (bombarders). The transmission frequency for the RFID system is 530 kHz and the transmission frequency for the bombarders is 400 kHz. The RFID system works through an antenna embedded in a pallet and a stationary read/write head. The bombarders are positioned on a platform overhead. The normal sequence is for a pallet containing a bulb to move via conveyor to a read/write station where information is taken from and added to the pallet. The pallet is conveyed through several different processes, being read/written on roughly 8 occasions. One of the processes contains an RF generator. We are experiencing problems with the RFID system when the RF generators are on. The read/write system operates properly when the RF generators are off. We have determined that the RF generators are creating an interference that does not allow the RFID to operate properly. Initially, w! e built copper shields in the area of some of the RFID stationary heads. This did not seem to help. We also placed EMI suppressors on the RFID cables(near the read heads). This also was not helpful. I have spoken to a company that suggested the use of Ferrite tiles to absorb the interfering waves. The problem with these tiles is that they are very brittle and difficult to use for shields. The concept sounds good but I don't have much flexibility in where I can place the shields. I am currently trying to use ferrite magnets attached to the copper guards. Any help/suggestions you could give me would be greatly appreciated. ===end paste== Thanks for any suggestions; reply as you see fit. WmFlanigan --- 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. --- 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: Surges on shielded lines
Dave, Figure 13 is indeed the correct setup to use for cables with the shield connected at both ends. In addition to the isolation transformers shown, the ground connection on EUT 1 must be temporarily disconnected for this test. For line cord connected 120V units I just use a cheater plug (3-wire plug adapter) without the ground lead. The intent is to force ALL of the surge current down the cable shield towards EUT 2. If done correctly the test generator readouts will indicate very low peak voltages and HUGE peak currents. The chassis connection from EUT 2 to Earth reference should be beefy (ie. heavy braid) to get a proper test. Scott Lacey -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Dave Wilson Sent: Friday, September 28, 2001 1:29 PM To: 'emc-p...@ieee.org' Subject: Surges on shielded lines I'm trying to get surge testing done on a DS3 interface against EN61000-4-5. According to the standard, the test set-up in figure 13 should be used. The figure shows the test generator connecting to the chassis - can someone confirm that is how the test is done - i.e. the surge is applied to the chassis, and hence the shield? Thanks in advance, Dave Wilson Alidian Networks --- 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. --- 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: EN 61000-3-3
EN 61000-3-3Josh, EN 61000-3-3 only mentions voltage fluctuations and flicker impressed on the public low-voltage system. Inrush current is not specifically measured, although it certainly affects the amount of voltage variation caused by the Equipment Under Test (EUT). To perform the test a controlled impedance (reference network of Fig. 1) is inserted between the ac source and the EUT. The unit is then operated normally while the voltage at the EUT input is monitored. What the test measures is the difference between the source voltage and the EUT input caused by the operation of the EUT. Washing machines and dishwashers may cause particularly nasty flicker because of solenoid valves and motor starting currents. EN 61000-4-11 does mention peak inrush current in regard to qualifying the ac source. The source must be capable of supplying more inrush current then the EUT peak inrush current (30% reserve). However, you would only need to test to EN 61000-4-11 if the appliance had electronic controls (as many do today). Although it may be possible to measure EUT peak inrush current and extrapolate the results, this would not comply with the requirements of EN 61000-3-3. Once the reference network is aquired (or built) the test is pretty straightforward. Best Regards, Scott Lacey Test Engineer (contract) EMC, Safety, Performance Verification -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Joshua Wiseman Sent: Friday, August 31, 2001 2:04 PM To: Emc-Pstc (E-mail) Subject: EN 61000-3-3 Hi all, I have recently heard of a requirement in the Flicker standard for In Rush current measurements. My understanding of the test is that the EUT is manually turned on and off 24 times. During these times dmax is measured. You then take the highest and lowest readings and throw them out. You then average the remaining 22 readings. This has been posed to me from a customer and I can not find any supporting information other than the fact that some test equipment manufacturers are beginning to implement the testing capability in their systems. Any information on this would be greatly appreciated. Thanks in advance for all the help. Regards, Josh
RE: Medical application-Isolation voltage
Ron, You will probably have a hard time finding a converter suitable for this application. Most medical devices are either (if low current draw) battery operated or use a medical grade line-frequency transformer. In the latter case they will also use a medical grade (low leakage) line cord. These have fillers that reduce capacitance between wires. The transformers are often of toroidal construction. Many manufacurers will make these as either 1:1 or stepdown types. Using a 1:1 in front of an ac-dc converter would not be very cost effective. Another possibility may be to use a rechargeable battery with a high isolation relay to switch between charge and operate. You could then use an ac-dc of lower rating to recharge the battery. This is a good compromise for equipment of medium current draw/short patient contact time. Without knowing the particulars of your situation I cannot give more specific advice. Best Regards, Scott Lacey Test Engineer (contract) EMC, Safety, Performance Verification -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Ron Sent: Wednesday, August 29, 2001 11:26 AM To: EMC Subject: Medical application-Isolation voltage I have a medical application that requires double insulation from the Mains to an applied part according to IEC60601. IEC60601 states that for a reference voltage of 250v and double insulation, the test voltage is 4000v for 1 min. I am assuming that the voltages are RMS values. How does one go about meeting the 4000v test when the highest rated ac-dc converter I can find is 3500v RMS continuous. Any help is appreciated. Thanks. Ronald Cyprowski Vascor Inc. 566 Alpha Drive Pittsburgh PA 15238 412-963-7438 x139 r...@vascor.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: No longer online until our new server is brought online and the old messages are imported into the new server. --- 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: Manufacturing Hipot Testing
Don, I do not believe that circuit-to-circuit testing is required between low-voltage circuits. The test is intended to prevent shock hazards caused by insulation leakage between high-voltage circuits and low-voltage circuits. I would group the circuits for production testing and only test them separately (for diagnostic purposes) if the test failed. Scott Lacey -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of don_macart...@selinc.com Sent: Friday, August 17, 2001 2:13 PM To: emc-p...@majordomo.ieee.org Subject: Manufacturing Hipot Testing Dear Group: A Hipot standard which we must run for CE compliance requires that circuit-to-circuit and circuit-to-ground testing be performed on a routine basis. The test is applied for 10s. The products I deal with have many circuits (Inputs, outputs, etc.) so test time is excessive . To speed test time the standard allows for grouping of similar circuits and decreasing the test time to 1s (with increased voltage). There is a problem with the grouping method because faults between circuits in the group are masked. A better way of performing dielectric strength testing would be to automate a process where each individual circuit is hipot tested to ground for 1 second. The problem is that this method doesn't match what the CE standard requires. Some of you have probably been in similar circumstances. What did you do? What do you suggest? Do I meet the standard no matter the cost? What is the risk of having my CE Mark pulled and perhaps my company sued if I do not meet the entire standard? Regards, Don MacArthur --- 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: current carrying conductors
Richard, The larger single wire, with appropriate ring lug, is actually the preferred construction. The two wire method is used in cases where something else in the system, such as a multi-wire connector, will only accept the smaller gauge wire. In that case each ring lug MUST be secured with its own star washer and nut. The stack up would be: Ring lug #1, star washer, nut, ring lug #2, star washer, nut. The screw or stud must be long enough for the top nut to have full thread engagement. Hope this is of help. Scott Lacey -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Stone, Richard A (Richard) Sent: Friday, August 17, 2001 9:01 AM To: emc-p...@majordomo.ieee.org Subject: current carrying conductors Group, can you substitute one large wire 6 awg. ( handlles 63 amps. max ) for two smaller wires ( 10 awg. carries 32 amps. max. ) in Parallel. They would 1/2 the current and disperse heat better. The accepting screw terminal would allow for proper threading and tightness of connection. since you would have 2 ring lugs on one terninal instead of two. thank you, Richard, --- 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,
Useful Typing Shortcuts
To the group, While the thread Re:Typing Shortcuts is quite interesting and entertaining, there is a typing shortcut that is very useful when typing test reports. Instead of repeatedly typing some long title such as Really Big Widget you just type RBW throughout the report. Later you you use the word processor's search and replace function to substitute the actual text. I find that it saves me hundreds of keystrokes in a typical report. Scott B. Lacey Test Engineer --- 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: Capacitor Discharge Test
Joe, The situation which you describe is absolutely a failure. If you doubt this (and I am not trying to be flip) try using two fingers (OF THE SAME HAND!) instead of the meter. This is what your customers might experience. If you have that much capacitance to hold a charge at that level after five seconds you need to do something about it. I would start by tracing out the wiring. Normally the switch should isolate the unit from the line, especially if a double pole unit is used. It sounds like a wiring error. I once saw a design engineer get a 6kV jolt through the hip from a unit equipped with safety interlocks that had accidently been bypassed during a wiring change. He was leaning against the frame with the interlocked(?) covers removed. If all else fails, I would suggest a bleeder resistor across the capacitance, adding a relay to isolate the line cord from the capacitance, or something of that nature. It would be normal for the unit to be switched off before being unplugged. 100 plus volts across the pins could be very unpleasant. Best Wishes Scott B. Lacey -Original Message- From: owner-emc-p...@ieee.org [mailto:owner-emc-p...@ieee.org]On Behalf Of marti...@appliedbiosystems.com Sent: Friday, May 11, 2001 12:31 PM To: emc-p...@majordomo.ieee.org Subject: Capacitor Discharge Test We evaluate our laboratory equipment to UL 3101-1, CSA 1010.1 and EN 61010-1. Section 6.10.3 of UL 3101-1 states If plug pins of cord-connected equipment receive a charge from an internal capacitor, the pins shall not be HAZARDOUS LIVE 5s after disconnection of the supply. We have always performed this test with the power switch in the ON position and would have the unit running then unplug the power cord and take our reading on the oscilloscope. We have never measured any voltages above the HAZARDOUS LIVE limits of 30Vrms, 42.4V peak or 60Vdc. Our new NRTL Engineer has now also requested us to perform this test with the power switch in the OFF position. With the switch in the off position our voltages after 5 seconds are close to line voltage. The NRTL is considering this a failure. However, UL 3101-1 also states in Section 6.10.3 For plugs receiving a charge from an internal capacitor, the measurements of 6.3 are made to establish that the levels of 6.3.1.3 are not exceeded. 6.3.1.3 requires measuring the overall capacitance from the unit. Our NRTL states that there is no method available to measure the overall capacitance of the unit. Has anyone else in the group had any experience with this issue? Does your NRTL require testing with the switch in the OFF position? Do your units fail with the switch in the OFF position? Is it a failure just because the voltage limits are exceeded, or is it only a failure if the current and capacitance limits are exceeded. (Similar to the Permissible Limits Requirements). Have you had any experience with NRTL's not being able to measure the overall capacitance? All responses are greatly appreciated. Regards Joe Martin Applied Biosystems marti...@appliedbiosystems.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: AC Power Primer?
Rick, and group members, I thought that I would weigh in with an opinion on this one. The definition of phase should be determined by the requirements of the equipment. If the equipment only requires single phase power, regardless of voltage, then that is what should be specified. It does not matter if this single phase is derived from a three phase source, it is still single phase. One way to determine this is to ask yourself if the equipment could be powered from a single phase electronic ac source. In my experience true two phase equipment is extremely rare. Instead, what we usually find are racks of equipment intended to be supplied from split phase (such as the typical U.S. residential service). This is because the rack either contains a mix of 120V and 240V equipment, or the 120V equipment draws too much current for a single circuit and must be split into two groups. None of these setups actually require two phases of the same source and could easily be rewired to operate from completely separate circuits. If anyone is still confused, here is some (greatly simplified) background on electrical power generation. Single phase alternators (often mistakenly called generators) produce a single sinusoidal cycle for each revolution of the input shaft. Frequency is determined by rotational speed. If an additional connection is made at the midpoint of the winding the alternator becomes a split phase type such as the 120V/240V types commonly sold as portable power sources. Three phase alternators have additional windings that each produce a single sinusoidal cycle for every revolution of the input shaft. These waveforms are staggered in time so that the peaks do not coincide with each other. This is the most efficient way to generate electrical power. This is why power companies use them. Automobile alternators are also three phase. The outputs are rectified by diode pairs to produce a pulsating dc output. The battery acts as a filter. If an oscilloscope lead is placed right at the alternator terminals a slight trace of the waveform can be seen. It is possible to detect blown diodes that way. Scott Lacey -Original Message- From: owner-emc-p...@ieee.org [mailto:owner-emc-p...@ieee.org]On Behalf Of rbus...@es.com Sent: Wednesday, May 02, 2001 4:31 PM To: emc-p...@majordomo.ieee.org Subject: AC Power Primer? I am in the process of assisting our publications group with documenting an ac power configuration. As simple as this sounds, it turns out there are varying opinions in our engineering group regarding the naming convention for input power, in particular single phase verses two phase. We all probably agree that a phase to neutral connection is single phase and devices that use all thee phases, whether they are 208V 60Hz or 400V 50Hz, are truly three phase. The discussion heats up when you are talking about a phase to phase connection on a three phase distribution (208 or 400V). Is this called single phase or two phase? It has been suggested that in the European community it is called two phase, while in the U.S. we call it single phase. I am looking for opinions or discussion on this issue. On a related note in the U.S. we have 240V 60Hz (two 120V drops) coming into our into our homes. This is provided by a transformer with a center taped winding. On the outside legs of the transformer we have 240V but between either outside leg and neutral (center tap) we have 120V. I would call this a single phase system with two additive (in phase) 120V windings. Again others have called this two phase. My apologies to the group if this is a stupid question. Its just one of those nagging questions. Rick Busche Evans Sutherland Salt Lake City, Utah rbus...@es.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
RE: Decoupling Capacitors
Chris, Thank you for the interesting story. Unfortunately this case is not all that unusual. About a decade or so ago (names have been changed to protect the guilty) I was working in the hardware engineering group at a company that had just instituted an aggressive cost-reduction program. Thanks to a lucky break, we managed to hear about the latest cost reduction victory before any product was shipped. Manufacturing had decided to save money by eliminating those useless decoupling caps - ALL of them! They removed all the decoupling caps from 2 boards and re-ran the ATE tests. The boards passed, so they got an engineer to sign off on the ECO. This (mechanical) engineer had always wondered if those darn caps were really needed so he was more than pleased to sign off. We put an immediate halt to the cost reduction. I still have nightmares about what could have happened to our customers if that one had sneaked through. The product was buggy enough as it was! A couple of things need to be mentioned. One is that there were generous cash bonus awards for cost reductions. This caused a gold-rush mentality to take hold. People had strong incentives to cheat by making endruns around the normal review process. Another is that, due to politics, the Mechanical Engineering group had almost total control over the entire PCB process. A PCB is not just a mechanical object. It is a complex electronic component. I have seen great designs ruined by lousy layouts and mediocre designs rescued by careful layouts. Again, Thank You Chris for taking the time to relate this experience to us. Scott Lacey -Original Message- From: owner-emc-p...@ieee.org [mailto:owner-emc-p...@ieee.org]On Behalf Of Chris Maxwell Sent: Friday, January 26, 2001 9:38 AM To: 'EMC-PSTC Internet Forum' Subject: Decoupling Capacitors Just a little personal experience I want to relate. The EMC people can really appreciate this. Sorry about the long, conversational tone, but I think it will help people appreciate how much effort could have been prevented by following simple EMC design rules. One of our products has a motherboard with an ISA bus with 7 standard connectors. Over the past 7 years or so, we have taken advantage of this flexibility to use processor, VGA, ethernet and serial extender cards from numerous third party vendors with quite a bit of success. About a month ago, we started having troubles with an 8 port serial expansion card that we buy from a third party vendor. Some of the units would fail the serial comm test during the final quality test before shipping the units. We started testing samples extensively and set up some overnight tests to exercise the cards. We found that some cards would run indefinitely, others would fail. Sometimes they would fail after 1 minute, sometimes after 10 hours. We considered interrupt servicing (software) problems, bad chips, faulty connectors ... We then did about two weeks' worth of isolation testing, where we would shift boards between units, trying different software, firmware, hardware, processors (cookware?) configurations. We found only one common thread. That was, bad boards would always fail, although the time to failure was random. Good boards were always good. We then started swapping chips between good boards and bad boards. We swapped RS-232 drivers... no change. Uarts... no change. Processors ... no change. Memory... no change. Firmware... no change. We then swapped 3each 74LS374's and 2each 74LS373's all at once Aha! the bad board became good and the good board became bad. We thought we were narrowing in. So, we put the 373's back so that only the 374's were swapped. Suddenly, neither board would fail after an entire day's testing. Both boards became good? This brought our isolation testing to a screeching halt. We thought we were on the trail of finding a bad chip either by date code, manufacturer ... something. But when both boards went good this hypothesis went out the window. (For those who are curious, we did put the chips back so that all 5 were swapped and got our good and bad boards back.) We then sent one good and one bad board back to the manufacturer. They couldn't duplicate the problem. Their owner talked to our software guy and suggested changes in interrupt handling, handshaking, initialization ... None of this worked. About three weeks ago, my boss was sitting down with us evaluating the boards, we were looking for differences in manufacturers, date codes, bad solder joints ... He made a casual comment that the board didn't have many decoupling caps. ( You know, those $1 per ton, ubiquitous, little yellow gumdrop, 0.1 uF capacitors). At the time, we all agreed, but thought nothing of it. This product has been stop-ship for about a month. We have customers screaming, marketing is asking for daily updates. The guys in manufacturing are renting hotel rooms to store backed up units (that part's just a joke). You get
RE: OATS Turntable Canopy
Richard, Before using PVC pipe, I would suggest testing it to see if it absorbs RF (Some do!). Place a small sample in a microwave oven, along with a mug of water to load the oven. If the PVC sample gets significantly warm after 1 minute try another type. Some PVC pipes have fillers added. Metallic fillings will cause problems. (A neat trick from the crystal radio builders, who can't tolerate losses in PVC coil forms.) Scott Lacey -Original Message- From: owner-emc-p...@ieee.org [mailto:owner-emc-p...@ieee.org]On Behalf Of Lichtenstein, Ross Sent: Tuesday, December 26, 2000 4:08 PM To: wo...@sensormatic.com Cc: emc-p...@majordomo.ieee.org Subject: RE: OATS Turntable Canopy Richard, I think that if I were trying to make an inexpensive environmental cover for an OATS turn-table, I would consider using PVC plastic pipe and fittings, similar to what you may have seen is used to fabricate patio furniture. I think you can find all the fittings necessary to build a simple framework, and then just cover whatever portion of it you want with black plastic builders film, or those inexpensive blue plastic tarps found in many discount stores (you may need to cut out the metal grommets on the tarps and replace them with any of several available plastic types. Good luck, Ross -Original Message- From: geor...@lexmark.com [mailto:geor...@lexmark.com] Sent: Friday, December 22, 2000 11:53 AM To: wo...@sensormatic.com Cc: emc-p...@majordomo.ieee.org Subject: Re: OATS Turntable Canopy Richard, Last year at the beach, I bought one of those cheap (er, inexpensive) gazebo-like canopies. It came with lots of metal tubes which had to be put together to form the upper canopy support and the legs. It was about 8' x 8' and 6' tall. However, if one replaced the metal tubes with wooden dowel material, something like this would provide a cheap shelter. The corners usually come with a means to peg into the ground, given the winds at a typical beach. For this you might need to find some plastic or other non-conductive tent pegs. Just a thought. George woods%sensormatic@interlock.lexmark.com on 12/22/2000 11:00:19 AM Please respond to woods%sensormatic@interlock.lexmark.com To: emc-pstc%majordomo.ieee@interlock.lexmark.com cc:(bcc: George Alspaugh/Lex/Lexmark) Subject: OATS Turntable Canopy I want to erect a simple, low cost removable canopy over our turntable at our OATS to protect the EUT from light rain and our Florida sun. Is anyone aware of an off-the-shelf option? Has anyone constructed a simple canopy and would like to share their design and/or experience (good and bad)? Richard Woods --- 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: Cell phones and humans
Paolo, This sounds like something worthy of investigation. My guess would be the effect of the wet concrete grounding the highly capacitive human body, effectively eliminating the bottom half of the dipole (The built in antenna is the top half). Of course, this probably only happens in marginal signal areas, as I've many times seen cell phones used in and around pools. Some time back I did some informal experiments with hand-held transceivers and portable receivers of various types. Some radios worked better with an earth ground wire attached to the chassis, and some worked worse. In some cases touching an earthed piece of metal with the free hand was enough to cause dramatic change in signal quality. Scott Lacey -Original Message- From: owner-emc-p...@ieee.org [mailto:owner-emc-p...@ieee.org]On Behalf Of Roncone Paolo Sent: Saturday, September 23, 2000 6:19 PM To: 'emc-p...@ieee.org ' Subject: Cell phones and humans Group, the subject of possible biological effects of cell phones is having a lot of attention these days and it was already touched in this forum. I'd like to get opinions about what my wife just told me. I don't know if this should be classified as influence of cell phones on humans or influence of humans on cell phones. The story is as follows: my wife was talking on her cell phone while walking by a swimming pool. As she steppen right on the wet border of the pool (she was bare foot) the line went down. But just after stepping back on dry ground (just a step or two back, so the signal level shouldn't have changed so much) the line got back and she was able to resume her conversation. She told me she didn't step back again on the water, just to check if the phenomenon was repeatable. I honestly don't know if this is even worth of attention because of course it's not a laboratory or just even a controlled experiment. But if anyone out there has any guess or thinks there is an explanation... that would be welcome !! Paolo --- 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: Logo for Ventilation Hole
Koh, In my opinion, this is a totally unacceptable situation. Label or not, some of the units sold will eventually encounter a situation where the ventilation hole gets blocked. Since the design is nearly complete, your choices will be limited. I think that you must include an overtemperature shutdown device such as a bimetal, thermal fuse, or PTC thermistor. All coffemakers, portable hair dryers, and similar devices include them. If you do not, you run the risk of major lawsuits, especially in the U.S. market. If a child becomes injured the financial penalties could be massive. Scott Lacey -Original Message- From: owner-emc-p...@ieee.org [mailto:owner-emc-p...@ieee.org]On Behalf Of Koh Nai Ghee Sent: Monday, September 04, 2000 9:31 AM To: EMC-PSTC Subject: Logo for Ventilation Hole Hi EMC-PSTC group, A team within my company is currently designing a amplifier speaker unit. Due to the current drawn is high and heat are dissipated. Therefore the encloseure need some ventilation hole. Unfortunately, till the very late stage of the design cycle, they found out if this ventilation hole was blocked, it will cause the plastic enclosure to melt. A question was asked, Is there a safety label/logo that we can affixed onto the plastic enclosure so that to tell user not to block this enclosure? (Or not to place it in a area where the ventilation will be blocked.) I've never seen such label or logo before. Has anyone out there seen such type of label/logo? Any advice from the group would be much appreciated. Regards Koh --- 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: UL Acceptance of On-Line Manuals
Joe, First, use Adobe Acrobat (.pdf) for the actual manuals. This is rapidly becoming the defacto world standard for on-line documentation. You can link to them from .html web pages easily. You can also burn them onto a CD-ROM if you need to include manuals with the product. Acrobat has a catalog feature that will allow the user to click on a title in the document and immediately open that page. In my current assignment, I regularly retrieve .pdf integrated circuit specifications from the manufacturers web pages. The printed pages are razor sharp, 8-1/2 x 11 data sheets. You can (with the licensed software) print to a .pdf file from any application, including schematic packages. The reader is available for free. I once demonstrated the ability of Acrobat for a client. By clicking on the appropriate line of a top level Bill of Material the appropriate document was immediately displayed - Schematic, PCB artwork, mechanical drawing, component specification, etc. The down side is that you need a modern computer and laser printer to get the most out of it. I have no experience with how the EC and various agencies feel about this. All the documentation I worked with was for company personnel and technically savvy customers. Scott Lacey P.S. Disclosure: I have no financial interest in Adobe Systems or any other software company. I just like the product! -Original Message- From: owner-emc-p...@ieee.org [mailto:owner-emc-p...@ieee.org]On Behalf Of marti...@appliedbiosystems.com Sent: Thursday, July 27, 2000 6:11 PM To: emc-p...@majordomo.ieee.org Subject: UL Acceptance of On-Line Manuals We are planning to switch over to an on-line system for our User Manuals. Does anyone have any experience with using an on-line system? Does the user have the same access as with paper manuals? What are the downsides of such a system? Has anyone dealt with UL and the European Union on their acceptance of on-line manuals? All information is appreciated. Regards Joe Martin marti...@appliedbiosystems.com --- 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: 8591EM monitor output
Jeff, I think the piece of hardware you need is an RF Modulator. These output your video on Channel 3 (sometimes switchable to channel 4). Should be available for $25-$50 dollars. Try MCM Electronics (800 543-4330)if you can't find one locally. The one I have is their P/N 33-1480 Audio/Video Modulator. It is about 3 x 5 x 1, with an attached (120V) line cord, and a switch to select CH3/CH4. Scott Lacey -Original Message- From: owner-emc-p...@ieee.org [mailto:owner-emc-p...@ieee.org]On Behalf Of Jim Bacher Sent: Monday, July 24, 2000 3:42 PM To: Bailey; Jeff; 'emc-pstc' Subject: Fwd:8591EM monitor output forwarding for Jeff. Reply Separator Subject:8591EM monitor output Author: Bailey; Jeff jbai...@mysst.com List-Post: emc-pstc@listserv.ieee.org Date: 7/24/00 12:06 PM Hello all, Have any of you successfully hooked up a television to an HP8590 series EMC analyzer? The monitor output does provide NTSC format, I am now assuming that I need to provide a carrier for the monitor output to ride on in order for the TV to see the NTSC signal and know what to do with it. Is there an easier way to do this than to build my own modulator? Thanks, Jeff Bailey Compliance Engineering SST - A Division of Woodhead Canada Phone: (519) 725 5136 ext. 363 Fax: (519) 725 1515 Email: jbai...@sstech.on.ca Web: www.sstech.on.ca --- 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: PDF file copy method
Barry, If the protections are set so that you can neither select text nor print, you are pretty much out of luck. If the problem is that the pdf file was created from a scanned document you may be able to print to a fax file (if you have a fax modem card and appropriate software. Many fax programs have OCR (Optical Character Recognition)capability. You can print to a stored fax file, and then open it as if it were a received fax, using the OCR input option. Some OCR programs are better than others at recovering text correctly. It's worth a try if you or a co-worker already have the software. Just a thought. Scott Lacey At 01:59 PM 7/17/2000 -0700, Barry Ma wrote: Hi, When reading an EMC article in PDF file, I sometimes want to copy a couple of sentences or paragraph to my MS WORD document. Most of times I failed. But a few times I could do it. I don't know why. Do you have the same experience? --- 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: Radiated Immunity
Radiated ImmunityJohn, I read an article some time ago regarding the use of a spectrum analyzer equipped with a tracking generator to explore near-field resonances in cables, etc. A near-field probe (loop) was used in conjunction with an inexpensive (Mini_Circuits) combiner to explore RF Immunity issues. I think the author was working at H-P when he wrote the article. Sorry I can't remember where the article was published. Scott Lacey -Original Message- From: owner-emc-p...@ieee.org [mailto:owner-emc-p...@ieee.org]On Behalf Of John Juhasz Sent: Wednesday, July 12, 2000 11:25 AM To: 'emc-p...@majordomo.ieee.org' Subject: Radiated Immunity Having a Radiated Immunity problem (300-320MHz - 3V/M ) that I need to troubleshoot . . . I don't have a screen room to work in . . . I want to troubleshoot down to the circuit or component level . . . is there any type of 'probe' that can be used instead of creating a full-field in a chamber? Any ideas . . . ? Haven't had a problem like this yet . . . John Juhasz Fiber Options Bohemia, NY 631-419-2324
RE: Are NTCs Safe to Use in Electrical Equipment
Jim, Replacing the switch with a toggle type dimmer will greatly lengthen the service life of bulbs. I have them in bedrooms and the bathroom. The main intent was to prevent being jolted awake by bright lights if it were necessary to get up at night. Because they look like ordinary light switches, visitors have no trouble operating them. As to using NTC thermistors, I would recommend that you NOT use them inside of an electrical box. They do get quite hot, and even if they did not damage wire insulation, you might be risking your insurance coverage in the event of a fire. I have used them in the past to reduce inrush currents in power supplies, but these were forced air cooled. Without forced cooling, they provide almost no protection if power is re-applied almost immediately after shutoff. By the way, mechanical vibration may be the real culprit. I used to work in a place where the bulbs failed with alarming frequency in our old shield room. Leaving the ventilation blower off reduced the failure rate. Fragile filaments hate to be shaken. Scott Lacey -Original Message- From: owner-emc-p...@ieee.org [mailto:owner-emc-p...@ieee.org]On Behalf Of Jim Eichner Sent: Monday, July 10, 2000 2:35 PM To: emc-p...@majordomo.ieee.org Subject: RE: Are NTCs Safe to Use in Electrical Equipment On the subject of NTC's, please allow me a slight detour from the compliance world to the real world. I have a circuit in my house that blows light bulbs far more often than any other. I can't determine any reason for this - the voltage seems normal and there aren't any transient-producers on that same circuit (that I'm aware of). Long life and rural-duty bulbs make little or no difference. Instead of figuring out the root cause, I'm considering resorting to trying to deal with the symptom (blown bulbs) by putting an NTC in series with the light fixture somewhere. My thinking is that the mechanism that blows an incandescent bulb filament is related to the high inrush current into the cold (and therefore low R) filament, and the physical and thermal stresses that that inrush causes. Any comments on how likely this is to help, and whether or not I can safely put an NTC in an junction box full of wires? I'd check the NTC's temperature under load (they get hot) and compare that the the temp. rating of the wires in the box. I'd also insulate the bare legs of the NTC and try to make sure it isn't touching anything else. Anyone familiar with the failure modes of these things? Thanks, Jim -Original Message- From: Peter Merguerian [mailto:pmerguer...@itl.co.il] Sent: Monday, July 10, 2000 7:58 AM To: emc-p...@majordomo.ieee.org Subject: Are NTCs Safe to Use in Electrical Equipment Dear All, I have seen some design where NTCs are used to limit inrush currents in motion controllers. Q. Are NTCs safe and reliable as means to limit inrush currents? Q. Are there safety considerations to consider for circuits employing NTCs? Q. Are there any Approved (previously evaluated) NTC components out there? I appreciate all of your comments and/or links regarding the use of NTCs in electrical equipment. Thanks Peter Merguerian Managing Director Product Testing Division I.T.L. (Product Testing) Ltd. Hacharoshet 26, POB 211 Or Yehuda 60251, Israel Tel: 972-3-5339022 Fax: 972-3-5339019 e-mail: pmerguer...@itl.co.il website: http://www.itl.co.il --- 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: 61000-4-8 Ground Plane
Bob, The standard (in the definitions section) only says that the ground plane is used as a common reference for the magnetic field generator and the auxiliary equipment, but I suspect that safety is a major reason for it being used. Without a good ground reference there is a possibility that dangerous potential differences could be created by the very strong power-frequency magnetic fields used. Naturally, the GRP must be of non magnetic material to prevent it from shunting some of the magnetic flux. Scott Lacey -Original Message- From: owner-emc-p...@ieee.org [mailto:owner-emc-p...@ieee.org]On Behalf Of rehel...@mmm.com Sent: Friday, June 16, 2000 10:32 AM To: emc-p...@majordomo.ieee.org Subject: 61000-4-8 Ground Plane Can someone explain to me why a ground plane is required in the test setup for EN 61000-4-8 (power frequency magnetic fields)? Thanks, Bob Heller 3M Company --- 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: 1-10GHz source
Marvin, This is excellent! This is exactly the sort of item that makes life easier for us. Please post as much information as possible, if you would not mind. I agree that a lead-acid cell would work best in this application. I would suggest a 6-volt unit used with a low-dropout 5-volt regulator. I would keep the charger separate for ease of use. A 6.9 volt supply could float charge the battery for long periods of time without damage. An LM7805 5-volt regulator boosted via resistors would work, as would an LM317 with appropriate resistors. I would use a switched dc jack for the charger input. These disconnect the battery from the load when the (dc)plug is inserted. 5.5 by 2.5 mm is one of the more common sizes in use. Scott Lacey Contract Engineer (EMC, Safety, Product Development) sco...@world.std.com (I have transferred my address for the emc-pstc to my personal email address after leaving Foxboro - my network account is not yet set up at my new assignment - the usual low priority with the I.S. people) -Original Message- From: owner-emc-p...@ieee.org [mailto:owner-emc-p...@ieee.org]On Behalf Of Jim Bacher Sent: Wednesday, June 07, 2000 7:37 PM To: Wolak; Marvin; emc-p...@ieee.org Subject: Fwd:1-10GHz source Forwarded for Marvin Reply Separator Subject:1-10GHz source Author: Wolak; Marvin marvin.wo...@marconi.com List-Post: emc-pstc@listserv.ieee.org Date: 6/7/00 2:47 PM A few weeks ago, there was some interest about references sources above 1 GHz. A few months ago I got tired of trying to find a source and made one myself. After some experimentation with batteries, I came up with a source which emits from 250 MHz through 10 GHz. The source emits the harmonics of 250 MHz. The source is stable to about 0.3 dB over the charge of the batteries which is from 12 to 22 hours depending on how they were charged. The field produced by the source, as tested at 3 m, is from approximately 68 dBuV/m to 85 dBuV/m in the range of 1 to 10 GHz. If anyone would like to see plots or stability graphs, let me know. If the response is overwhelming, I'll post it. Basically, what I came up with is as follows: The box is a simple aluminum project box, a circuit described below, 8 NiMh batteries (rechargeable), and a built in charger. The circuit was put together on a circuit board using a Radio Shack etch kit. A 250 MHz oscillator feeds directly into a Herotek 250 MHz comb generator. The output of the comb generator is put through a 10 dB attenuator and then connected to a sma bulkhead connector using a short coax jumper cable. The antenna is a sma m-f barrel with a wire attached to the center conductor. A case from a ballpoint pen was screwed onto the barrel to protect the wire. I tapped out the end of the pen case so the connector would screw on. Can't remember the manufacturer of the oscillator. The comb generator from herotek, (http://www.herotek.com/), has removable sma connectors on the input and output. I removed the input sma and connected it directly to the oscillator output. All in all, the circuit draws 173 mA. The power for the above is regulated by a 5V regulator with some simple power decoupling and diode protection. The first pass used AA alkaline batteries. This provided for only about 6 hours of operation. The second pass was with 6 C rechargeable alkaline batteries. This provided for about 14 hours of operation but the source stability was poor. The output at some frequencies would increase 2-4 dB over the life of the charge. Another drawback was that the batteries had to be removed to charge. I've since replaced the alkaline batteries with 8 Panasonic NiMh batteries. This has solved my stability problem (I can live with 0.3 dB variability). To charge the batteries a bought a MaHa battery charger, disassembled it, and mounted its circuitry in my box. The switchover from the load of the circuit to the charger is done through the main double pole-double throw switch. If I had to do it over, I would start from the power side. The NiMh batteries are not the best choice for a few good reasons but that was what I was stuck with if I was to keep the same box. Lead acid may be a better choice, but would require a larger project box, something like the popular EMCO Royce field source. I would be interested in feedback. There is plenty of room for improvement, and lots of talent on this board. If you have any questions, or if something is unclear, let me know. Marvin Wolak Marconi Communications Senior EMC Engineer, Product Integrity Ph: 724-742-7453 Fx: 724-742-7474 EMail: marvin.wo...@marconi.com --- 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
