Re: Transient Surge Suppression
Doug, One of the best resources I've seen on the topic is called PROTECTION OF ELECTRONIC CIRCUITS from OVERVOLTAGES, by Ron Standler (published by John Wiley and Sons, ISBN: 0-471-61121-2. Dave Tarnowski Senior Engnr. Whirlpool Corp. St. Joseph, MI Tel: 616-923-7287 __ Reply Separator _ Subject: Transient Surge Suppression Author: Douglas Best doug.b...@ifrsys.com at Internet List-Post: emc-pstc@listserv.ieee.org Date:8/25/99 10:13 AM Subject: Transient Surge Suppression Mighty Experts of EMC, I have a question concerning the determination of the right Transient Suppressor to use for controlling Lightning Surges. How do I determine the correct size and type of surge suppresser to use (MOV's, Spark Gaps, etc...) to help my power supplies survive the surge requirement of IEC 1000-4-5 to the AC mains? My equipment is all single phase with idle currents below 4 Amps. Any comments or advice would be greatly appreciated. P.S. My questions or comments do not reflect the opinions of my company or their lack of knowledge. :) Douglas BestCompliance Technician IFR America's Inc. Design Engineering RF Division Tel : +1 316 529 5327 10200 W. York St. FAX : +1 316 522 3676 Wichita Ks, 67215 e-mail: doug.b...@ifrsys.com - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Amplifier for measurements above 1GHz
I am hoping to purchase a 1 to 5 Ghz amplifier to be used in conjunction with a spectrum analyzer to measure emissions at 3m to FCC requirements. With a 1 MHz bandwidth into a HP microwave analyzer we can only currently measure at 1m. Can we get away with measurements at 1m? Can anyone recommend a low cost microwave amplifier that is suitable for the task? Thanks in anticipation of your response. John Cronin __ Get Your Private, Free Email at http://www.hotmail.com - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
RE: CE Marking requirements
Charles, If you want to CE mark a component which has no intrinsic value (that is, it must be operated via another component),is CE marking illegal? Also, is a Declaration of Incorporation (DOI) needed instead of a Declaration of Conformity (DOC)? --- Grasso, Charles (Chaz) gra...@louisville.stortek.com wrote: As far as I know, the EU has not adopted the insane FCC Class B compliance process. So there is NO procedure for marking a motherboard as a compliant unit. What you can do is test it in a system (just like the old days) and mark the motherboard based on that test ALONE. If I understand your requirement, you are looking to adopt the infamous CE+CE=CE approach. Again, this has proven NOT to work especially for emissions. Comments: (a) there is no requirement to test open chassis and that we can CE mark the board as compliant as long as we have shown that it can meet the class B levels within a chassis of our choosing. RESPONSE: There is no requirement NOR is there a process for open chassis testing. The EMC Directive (nor the guidelines) can help you here. (b) we are still required to perform open chassis tests, however, there is no 6dB margin and the board will have to meet the EN 50022 class B levels with the cover off. RESPONSE: Nonsense. There is NO open chassis test. WARNING: Be careful. The next thing the testhouse will try is the TCF route. Ugh. Thank you Charles Grasso Advisory Engineer StorageTek 1 StorageTek Drive Louisville CO 80027 M/S 4247. Tel:303-673-2908 Fax:303-661-7115 email:gra...@louisville.stortek.com RMCEMC Web Site: http://www.ewh.ieee.org/r5/denver/rockymountainemc/ -Original Message- From: michael.garret...@radisys.com [mailto:michael.garret...@radisys.com] Sent: Tuesday, August 24, 1999 2:44 PM To: emc-p...@ieee.org Subject: CE Marking requirements Well group, if you care to help out another American confused by the specific requirements for Europe, I would appreciate it. I seem to be getting varying stories from different test houses as to what is required for one of our products. These are big enough players that pitting one against another is not something I want to undertake at this point. We currently manufacture a motherboard which is sold both by itself and with a chassis which includes power supply, hard drive and floppy. We are currently going through our internal EMC validation to ensure that we meet both FCC Class B and EN 55022 Class B levels. Our experience on previous products has been if we clear emissions, we haven't had problems in other areas, but we'll be testing to EN 55024 of immunity, as well. The issue arises when we discuss testing of the system versus testing of the motherboard alone. Within the US, the FCC regulations permit an additional 6dB margin for open chassis measurement, so long as those frequencies fall back within the class B levels with the cover on. This does not appear to be a problem for our product. We have been told by different parties that for Europe, (a) there is no requirement to test open chassis and that we can CE mark the board as compliant as long as we have shown that it can meet the class B levels within a chassis of our choosing and (b) we are still required to perform open chassis tests, however, there is no 6dB margin and the board will have to meet the EN 50022 class B levels with the cover off. We're having a little more difficulty making things work using the (b) approach. I am specifically concerned about staying far enough below the levels that we're not going to potentially pass today and fail 6 months from now due to a slight drift in tolerances of components, test equipment or test engineers' dispositions. I have the texts of the EMC directive, as well as the test requirements specified in the above documents and I'm happy to wade through them if you can point me in the right direction. I will be heading that direction in the next day or two if I don't receive a response. I'm hoping, however, that someone in the group can shave a few hours of exceptionally captivating reading from my life by pointing me in the right direction. Regards, Michael Garretson Compliance Engineer RadiSys Corporation - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com,
RE: Grounding Bond Test
Rich The obvious question I would have is... why couldn't you test at a higher current for longer time meeting both requirements? For example 30A for two minutes. I know the document indicates a maximum current, but does this make sense? OK I guess I know understand what you mean by Technical Requirement vs. Technical Committee. -Original Message- From: Rich Nute [mailto:ri...@sdd.hp.com] Sent: Wednesday, August 25, 1999 2:37 PM To: carmen.fili...@leitch.com Cc: emc-p...@majordomo.ieee.org; fra...@csa.ca Subject:Re: Grounding Bond Test Hi Carmen: You ask how to resolve the difference between two, different production-line (routine) test standards. If your product is certified by CSA, then you test to the 30-ampere value. If your product is certified by a CB Certificate and Test Report, and the issuing body invokes EN 50116, then you test to the 25-ampere value. If your product is certified by UL, then you test to any current of your choosing. So, the answer to your question is: Whatever your certification house says. In essence, the requirement is proprietary to the certification house. The certification house can invoke any production-line test it feels is necessary. CSA uses 30 amps, 2 minutes. A certification house that invokes EN 50116 uses 25 amps, 1 minute as a maximum test. UL does not require a high-current test. The CSA 30-amp requirement derives from the fact that a CSA circuit-breaker rated 15 amperes (the most common 120-volt circuit in Canada) is not required to trip before 2 minutes at a current of twice rating, 30 amperes. So, the equipment grounding circuit must withstand 30-amperes for 2 minutes. The CENELEC 25-ampere requirement history is not at all clear. It has been in both European standards and UL standards as a type test for many, many years. It only appeared as a routine test when EN 50115 was published a few years ago. By the way, neither high-current test (as a production-line test) will identify continuity problems any better than a low-current test. The presumption is that the high-current test will identify a manufacturing defect in the grounding circuit, while a low-current test will not. In actuality, the grounding circuit, in order to pass the type test, had to be properly designed to handle the high current, no matter whether 25 amps or 30 amps. So, for the production-line, we need to be assured, by test, that the high-current circuit has been assembled correctly and with no defects. The high-current test WILL NOT identify loose screws if the conductors are making contact! The high- current test WILL NOT identify cut strands of wire if there are 3 or more strands in the circuit! (Feel free to duplicate these tests or any other grounding circuit defects you can imagine; the circuit will pass the high-current test!) The high-current test does not identify continuity problems any better than a low-current test. I did point this out to the EN 50116 committee when they asked for comments before it was published. Interesting that the committee ignored the data and required the test anyway! I guess the lesson is: don't confuse a technical committee with technical facts. Rich - Richard Nute Product Safety Engineer Hewlett-Packard Company Product Regulations Group AiO Division Tel : +1 858 655 3329 16399 West Bernardo Drive FAX : +1 858 655 4979 San Diego, California 92127 e-mail: ri...@sdd.hp.com - ps: In high-volume production, both the 1-minute and the 2-minute tests are unacceptable to the manufacturer. It seems that
Re: Grounding Bond Test
Hi Carmen: You ask how to resolve the difference between two, different production-line (routine) test standards. If your product is certified by CSA, then you test to the 30-ampere value. If your product is certified by a CB Certificate and Test Report, and the issuing body invokes EN 50116, then you test to the 25-ampere value. If your product is certified by UL, then you test to any current of your choosing. So, the answer to your question is: Whatever your certification house says. In essence, the requirement is proprietary to the certification house. The certification house can invoke any production-line test it feels is necessary. CSA uses 30 amps, 2 minutes. A certification house that invokes EN 50116 uses 25 amps, 1 minute as a maximum test. UL does not require a high-current test. The CSA 30-amp requirement derives from the fact that a CSA circuit-breaker rated 15 amperes (the most common 120-volt circuit in Canada) is not required to trip before 2 minutes at a current of twice rating, 30 amperes. So, the equipment grounding circuit must withstand 30-amperes for 2 minutes. The CENELEC 25-ampere requirement history is not at all clear. It has been in both European standards and UL standards as a type test for many, many years. It only appeared as a routine test when EN 50115 was published a few years ago. By the way, neither high-current test (as a production-line test) will identify continuity problems any better than a low-current test. The presumption is that the high-current test will identify a manufacturing defect in the grounding circuit, while a low-current test will not. In actuality, the grounding circuit, in order to pass the type test, had to be properly designed to handle the high current, no matter whether 25 amps or 30 amps. So, for the production-line, we need to be assured, by test, that the high-current circuit has been assembled correctly and with no defects. The high-current test WILL NOT identify loose screws if the conductors are making contact! The high- current test WILL NOT identify cut strands of wire if there are 3 or more strands in the circuit! (Feel free to duplicate these tests or any other grounding circuit defects you can imagine; the circuit will pass the high-current test!) The high-current test does not identify continuity problems any better than a low-current test. I did point this out to the EN 50116 committee when they asked for comments before it was published. Interesting that the committee ignored the data and required the test anyway! I guess the lesson is: don't confuse a technical committee with technical facts. Rich - Richard Nute Product Safety Engineer Hewlett-Packard Company Product Regulations Group AiO Division Tel : +1 858 655 3329 16399 West Bernardo Drive FAX : +1 858 655 4979 San Diego, California 92127 e-mail: ri...@sdd.hp.com - ps: In high-volume production, both the 1-minute and the 2-minute tests are unacceptable to the manufacturer. It seems that most certification houses will waive the long-term test in these cases! This seems to admit that the high-current test is not particularly valuable. - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Grounding Bond Test
Hello all, I want to clarify some of my thoughts regarding the ground bond specification for production line. EN 50116 for ITE specifies the earthing terminal or earthing contact may not exceed 0.1 ohms when 1.5 times the current capacity of hazardous circuits is applied, but not more than 25 A (ac or dc) for 60 seconds. The CSA standard C22.2 No. 0.4-M1982 Bonding and grounding of Electrical Equipment specifies for cord-connected equipment twice the rating of the attachment plug capacity, but not less than 30 A, 60 Hz current for 2 minutes. I am wondering which of these standards is applicable for routine test in production field. I think that EN 50116 is, but I am a little bit embarrassed by the CSA requirements of 30A and want to know your ideas on basis of a longer experience than mine. I appreciate any response to this e-mail. Thank you. Best regards, Carmen Filimon Safety Test Eng., Leitch Technology Int'l, Toronto - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Grounding Bond Test
Hello all, I want to clarify some of my thoughts regarding the ground bond specification for production line. EN 50116 for ITE specifies the earthing terminal or earthing contact may not exceed 0.1 ohms when 1.5 times the current capacity of hazardous circuits is applied, but not more than 25 A (ac or dc) for 60 seconds. The CSA standard C22.2 No. 0.4-M1982 Bonding and grounding of Electrical Equipment specifies for cord-connected equipment twice the rating of the attachment plug capacity, but not less than 30 A, 60 Hz current for 2 minutes. I am wondering which of these standards is applicable for routine test in production field. I think that EN 50116 is, but I am a little bit embarrassed by the CSA requirements of 30A and want to know your ideas on basis of a longer experience than mine. I appreciate any response to this e-mail. Thank you. Best regards, Carmen Filimon Safety Test Eng., Leitch Technology Int'l, Toronto - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re:RE: Concrete as an insulator??? -- and now FCC/FAA
Mike, I do not know if it is in the FCC rules or not, but your cell phone service provider may not take lightly such actions. Cell phones make use of line of site and low power to be a cell. Once you are up in the air, your phone can easily try to connect to every cell site in the state (and beyond). That means that you will tie up a large number of cell sites and possible cause interference to other users of the cell system. You may find your service provider turning off your cell service as a result. I am sure that some of the people who work for the manufactures of cell phones, who are on this list, can give a better idea as to how many cell sites you can tie up in the airplane. Being a ham radio operator I have seen ham's use repeaters, while in airplanes, it can and does get in the way of emergency communications. Just my two cents Jim Jim Bacher, Senior Engineer Paxar - Monarch email:jim_bac...@monarch.com voice:1-937-865-2020 fax:1-937-865-2048 Reply Separator Subject:RE: Concrete as an insulator??? -- and now FCC/FAA Author: Mike Hopkins mhopk...@keytek.com List-Post: emc-pstc@listserv.ieee.org Date: 08/24/99 5:25 PM If I'm not mistaken, there IS an FAA regulation prohibiting the use of cell phones in airplanes -- I have the regs at home and will look it up. Mike Hopkins mhopk...@keytek.com -Original Message- From: miksher...@aol.com [SMTP:miksher...@aol.com] Sent: Tuesday, August 24, 1999 11:13 AM To: gmcintu...@packetengines.com; ed.pr...@cubic.com; emc-p...@ieee.org Subject: Re: Concrete as an insulator??? In a message dated 8/23/1999 5:05:26 PM Central Daylight Time, gmcintu...@packetengines.com writes: Does anybody know why the FCC - not the FAA has regulations against using a cell phone in a private airplane. It is a little more obvious for a commercial airplane that use the fuselage as a return path from various equipment bays but private plans aren't wire that way - I don't think. There was a comment made that it interferes with the Cell system in some manner, any clues? Stated reason I've always heard, and which makes sense to me: one triggers multiple cells once one is airborne, which messes up a system that is designed to hand off a call cell to cell, based on signal strength and an assumption that the phone is on the ground. Mike Sherman FSI International - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
RE: Temperature Measuring of Magnetic Components
Hi Kamran, I've run into this problem myself. Usually, it is because the test conditions you use are different from what the vendor is using. They may be loading the EUT to full capacity and/or using a thermocouple attachment method different from yours. In the case where your product's configuration is not identical to the vendor, you can expect some discrepancy. Compliance agencies such as UL understand that your conditions of applicability are different from the vendor's and thus your data will be unique. If you wish to minimize the discrepancy, load the EUT to maximum rating and use a similar probing scheme as the vendor. In some cases, magnetic flux can be so great that it induces an undesirable EMF and reading error in which case you might have to run the EUT until thermal equilibrium occurs then, cut power and take a measurement sweep immediately afterward. UL for example, demands that the thermocouple probe be attached to the windings of the coil -with the thermocouple junction in direct contact with the wiring and NOT through core, ferrite or tape insulation (if the conductors are coated there is no need to remove the coating). I was just audited a couple weeks ago for COMPASS FUS and was reminded that the use of cyanoacrylate glue or thermal conductive epoxy to attach a thermocouple to a coil was entirely acceptable. Here's a tip in using thermocouples: It is best to force the junction wires of the thermocouple to fuse into a single point and to avoid using a junction made of twisted bare wires (which forms several thermocouple contact junctions and can cause errors). In the fabrication of the junction, I use a microtorch to fuse type 'J' thermocouples. Twist the wires together, but clip the excess off and leave enough that when you hit it with the torch a 'ball' fuses from the wires and consumes all the twists. This takes a little practice but works much better than using a zapper to 'arc' weld thin 30 to 36ga. wires (IMHO). I then check each channel for accuracy before attachment and test. On most thermocouple types the red wires are negative polarity, white is positive. The thinner the wires, the better ease in accessing tight spots and getting a good contact. Kyle Ehler kyle.eh...@lsil.com mailto:kyle.eh...@lsil.com Assistant Design Engineer LSI Logic Corporation 3718 N. Rock Road U.S.A. Wichita, Kansas 67226 Ph. 316 636 8657 Fax 316 636 8889 Fax 316 636 8315 -Original Message- From: Kamran Mohajer [SMTP:kmoha...@cisco.com] Sent: Tuesday, August 24, 1999 4:50 PM To: emc-p...@ieee.org Subject:Temperature Measuring of Magnetic Components Hello EMC-PSTCers, I wonder if anyone knows of the method of measuring temperature limits on magnetic components. I happen to get involved in this and found that my results are different than the vendors result by as much as 10-15 degrees on measuring on a same magnetic component. Even applying the thermocouple to different location on a coil seems to give you different results. Is there a method that I should be following to measure temperature with thermocouples methods, not change of resistance, on magnetic parts such as transformers, coils, etc.? Thanks, *** Kamran Mohajer DSL Compliance Lead Cisco Systems, Inc. Phone(408)-525-6121 Fax(408)527-0495 kmoha...@cisco.com *** - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
FW: Austria's 2.0kv impulse requirement
Posted for John: :-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-) Ed Price ed.pr...@cubic.com Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA. USA 619-505-2780 (Voice) 619-505-1502 (Fax) Military Avionics EMC Services Is Our Specialty Shake-Bake-Shock - Metrology - Reliability Analysis :-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-) -Original Message- From: Boucher, John [SMTP:j...@drexch1.dr.lucent.com] Sent: Wednesday, August 25, 1999 7:43 AM To: 'emc-p...@ieee.org' Subject: Austria's 2.0kv impulse requirement All: IEC 950 Second Edition Amendments 3 + 4 contain a Note for clause 6.4.2.1 (Impulse test) that states Austria requires a Uc of 2.0kv for cases b) and c). IEC 60950 Third Edition (now clause 6.2.2.1) has dropped that Notedoes this mean Austria dropped the 2.0kv variation / requirement? Thanks. John Boucher Lucent Technologies - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
SDRAM production line tester
Question from an ex collegue that's probably best fielded to the group. Which safety standard (European) would be applicable to a small (1 metre by 0.5 metre, height ??) machine used for end of production line testing of SDRAM's? The unit is non portable single phase (60 Amps max). Sorry but that's all the info. that I have been given. Suggestions?? Thanks PAul Excite -- Control Yourself. This E-mail brought to you by Excite's free E-mail service. Get your own E-mail address at http://www.excite.co.uk - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
RE: CE Marking requirements
The recent August 1999 issue of Conformity magazine indicates that indeed the test methodology of C63.4 does include the open chassis test and the 6 dB above limits. The article indicates a clarification was made about this process in a recent OET notice. The notice itself wasn't identified so you would have to search the FCC's site for it. Before one and all start throwing daggers and putting hexes on me. I want to point out that I am not endorsing the process, although I certainly understand, why folk like Michael might want this type of system. Finally, I will resist a dig at the sanity of many of the European rules. Gary -Original Message- From: Grasso, Charles (Chaz) [SMTP:gra...@louisville.stortek.com] Sent: Tuesday, August 24, 1999 4:18 PM To: 'michael.garret...@radisys.com'; emc-p...@ieee.org Subject:RE: CE Marking requirements As far as I know, the EU has not adopted the insane FCC Class B compliance process. So there is NO procedure for marking a motherboard as a compliant unit. What you can do is test it in a system (just like the old days) and mark the motherboard based on that test ALONE. If I understand your requirement, you are looking to adopt the infamous CE+CE=CE approach. Again, this has proven NOT to work especially for emissions. Comments: (a) there is no requirement to test open chassis and that we can CE mark the board as compliant as long as we have shown that it can meet the class B levels within a chassis of our choosing. RESPONSE: There is no requirement NOR is there a process for open chassis testing. The EMC Directive (nor the guidelines) can help you here. (b) we are still required to perform open chassis tests, however, there is no 6dB margin and the board will have to meet the EN 50022 class B levels with the cover off. RESPONSE: Nonsense. There is NO open chassis test. WARNING: Be careful. The next thing the testhouse will try is the TCF route. Ugh. Thank you Charles Grasso Advisory Engineer StorageTek 1 StorageTek Drive Louisville CO 80027 M/S 4247. Tel:303-673-2908 Fax:303-661-7115 email:gra...@louisville.stortek.com RMCEMC Web Site: http://www.ewh.ieee.org/r5/denver/rockymountainemc/ -Original Message- From: michael.garret...@radisys.com [mailto:michael.garret...@radisys.com] Sent: Tuesday, August 24, 1999 2:44 PM To: emc-p...@ieee.org Subject: CE Marking requirements Well group, if you care to help out another American confused by the specific requirements for Europe, I would appreciate it. I seem to be getting varying stories from different test houses as to what is required for one of our products. These are big enough players that pitting one against another is not something I want to undertake at this point. We currently manufacture a motherboard which is sold both by itself and with a chassis which includes power supply, hard drive and floppy. We are currently going through our internal EMC validation to ensure that we meet both FCC Class B and EN 55022 Class B levels. Our experience on previous products has been if we clear emissions, we haven't had problems in other areas, but we'll be testing to EN 55024 of immunity, as well. The issue arises when we discuss testing of the system versus testing of the motherboard alone. Within the US, the FCC regulations permit an additional 6dB margin for open chassis measurement, so long as those frequencies fall back within the class B levels with the cover on. This does not appear to be a problem for our product. We have been told by different parties that for Europe, (a) there is no requirement to test open chassis and that we can CE mark the board as compliant as long as we have shown that it can meet the class B levels within a chassis of our choosing and (b) we are still required to perform open chassis tests, however, there is no 6dB margin and the board will have to meet the EN 50022 class B levels with the cover off. We're having a little more difficulty making things work using the (b) approach. I am specifically concerned about staying far enough below the levels that we're not going to potentially pass today and fail 6 months from now due to a slight drift in tolerances of components, test equipment or test engineers'
Transient Surge Suppression
Subject: Transient Surge Suppression Mighty Experts of EMC, I have a question concerning the determination of the right Transient Suppressor to use for controlling Lightning Surges. How do I determine the correct size and type of surge suppresser to use (MOV's, Spark Gaps, etc...) to help my power supplies survive the surge requirement of IEC 1000-4-5 to the AC mains? My equipment is all single phase with idle currents below 4 Amps. Any comments or advice would be greatly appreciated. P.S. My questions or comments do not reflect the opinions of my company or their lack of knowledge. :) Douglas BestCompliance Technician IFR America's Inc. Design Engineering RF Division Tel : +1 316 529 5327 10200 W. York St. FAX : +1 316 522 3676 Wichita Ks, 67215 e-mail: doug.b...@ifrsys.com - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: Temperature Measuring of Magnetic Components
Dear Kamran, Obtaining a temperature test results that is 10-15 degrees higher or lower than your vendor is not unusual at all. We experience this all the time with major test houses. I have had many cases where an experience test engineer in a test house measures as much as 20 degrees lower or higher than our in-house measurements. This is because there are many variable/uncontrolable factors involved when measuring thermals. Thanks H.Ahmadi - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: Temperature Measuring of Magnetic Components
Kamran, As John Crabb pointed out, making measurements at different points will give you some variation due to hot spots etc. What most people miss is that thermocouple readings are affected by magnetic fields. To get a correct reading, turn power off and take a reading immidiately after the reading stabilizes. I have seen the reading change as much as 10-15 degrees when the power is turned off. Usually the reading jumps higher. I also noticed that how much the reading changes depends on where I placed the thermocouple. Usually the biggest change is when the thermocouple is placed between the core and the coil. When trying to correlate your readings with your vendor's make sure you're using the same type of thermocouple and measure at the same point. Find out if they made the measurement with power on or off. Several years ago I had the same problem. I called the manufacturer of the thermocouple I was using. They could not tell me how much my reading would change but recommended taking the reading with power off. Hope this helps. Regards, Fred Waechter Kamran Mohajer wrote: Hello EMC-PSTCers, I wonder if anyone knows of the method of measuring temperature limits on magnetic components. I happen to get involved in this and found that my results are different than the vendors result by as much as 10-15 degrees on measuring on a same magnetic component. Even applying the thermocouple to different location on a coil seems to give you different results. Is there a method that I should be following to measure temperature with thermocouples methods, not change of resistance, on magnetic parts such as transformers, coils, etc.? Thanks, *** Kamran Mohajer DSL Compliance Lead Cisco Systems, Inc. Phone(408)-525-6121 Fax(408)527-0495 kmoha...@cisco.com *** - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). -- Fred Waechter Sr. Applications Engr. SMPS Consulting w...@skybest.com Phone/FAX: 336-246-5236 - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: Temperature Measuring of Magnetic Components
Hello Kamran, I have been faced with this problem many times in the (nearly 35) years that I have been involved with such measurements. In my experience, this is the major and problematic correlation factor (in the product safety domain). It is the one that stands out above all others, when faced with correlation difficulties (especially when the tests are conducted on different continents as they were in my situation :-) Very slight changes in the immediate-area ambient temperatures and the electrical service where you are making the measurements can drastically affect the temperature readings as can the location of the thermocouples on the transformer under test (as you already noted). Consider the following possiblilites (not in any particular order) ; A) Be certain that there is no extraneous air-flow over the trafo (from a room-fan, people constantly walking by in the adjacent aisles, or room air-conditioning drafts. ( I believe ambient air-flow to be a major factor when you are faced with correlation difficulties) B) Be certain your input voltage is a clean sine-wave. Distortions in the input voltage waveshape will affect your data. (At one time we tried to use a low-distortion/low harmonics constant-voltage transformer to keep the line voltage constant during temperature tests - even that small amount of input distortion was sufficient to affect our results). C) If the trafo is in a switching-mode power supply, the currents being switched will likely be affecting the indicated temperatures. D) Why do you discount rise-of resistance ? I believe this technique integrates the temperature differences across a transformer and yields a more repeatable result (in my humble experience). E) One problem I've found in transformer construction is that air can become entrapped, by the impregnating materia, between the outer-wrap layers. This effects the temperatures measured on the outer surfaces (again, a thermocouple location problem). F) Another problem is the heating effect on the trafo of adjacent hot components (cold ones or sinks too, I suppose) when transformers are evaluated in an end-product. Be certain that you and your vendors (and your test agency) apply thermocouples in the same location/s. Consider submitting a transformer, with thermocouples attached by you, to your vendor/s and test agency/ies. This will, at the least, rule out thermocouple location (and its attachment) as a variable. G) Be certain that you are using high-grade (low error) thermocouples and calibrated equipment. Good Luck! Regards, Art Michael Int'l Product Safety News A.E. Michael, Editor P.O. Box 1561 Middletown CT 06457-8061 U.S.A. Phone : (860) 344-1651 Fax: (860) 346-9066 Email : i...@connix.com Website: http://www.safetylink.com ISSN : 1040-7529 - On Tue, 24 Aug 1999, Kamran Mohajer wrote: Hello EMC-PSTCers, I wonder if anyone knows of the method of measuring temperature limits on magnetic components. I happen to get involved in this and found that my results are different than the vendors result by as much as 10-15 degrees on measuring on a same magnetic component. Even applying the thermocouple to different location on a coil seems to give you different results. Is there a method that I should be following to measure temperature with thermocouples methods, not change of resistance, on magnetic parts such as transformers, coils, etc.? Thanks, *** Kamran Mohajer DSL Compliance Lead Cisco Systems, Inc. Phone(408)-525-6121 Fax(408)527-0495 kmoha...@cisco.com *** - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
3-Meter Chamber for Emission Pre-Scanning
To all my distinguished colleagues. I wish to thank you for your responses to my call for help, and inform you of the finial outcome. Some of you I have contacted directly and some I have not (due to time constraints) but I want to thank all that have responded very much. I have read and considered each reply. In summary, I was required to substitute a 10x10x22 ferrite tile chamber for a 10 OATS for emission pre-scan testing and needed fairly good correlation. To make a long story short here is what I did: The chamber had a metal floor that was naturally the major contribution to reflections. I placed ferrite tile square assemblies 2x2 Ft. from under the Biconilog running 3 meters to under the EUT table. The tile squares fanned out in the middle to form something like an oval. Now I have minimum reflections and once plotted gives me a curve very close to theoretical using a Biconilog and a Biconical antenna. The horizontal and vertical plot points fall all most on top of each other on the curve. I now have a ferrite tile tunnel, with only one major reflection at 150 MHz. which is stable and about 4 dB P-P. I am starting to test equipment which has returned for commercial labs and show a correlation of about 2.6 to 3 dB. Now this is not bad if I do say so myself. I only need to recheck the Field Uniformity, which I do not think will be adversely affected. Al Patrick, Sr. EMC Engineer - Manager of EMC Lab Operations Scientific-Atlanta Inc. al.patr...@sciatl.com 770 236 5148
RE: Temperature Measuring of Magnetic Components
Kamran, The method used by most of the better magnetics houses is to embed thermocouples into the transformer during construction of a sample. The resulting temperatures will be higher than external measurements. Scott Lacey -Original Message- From: Kamran Mohajer [SMTP:kmoha...@cisco.com] Sent: Tuesday, August 24, 1999 5:50 PM To: emc-p...@ieee.org Subject:Temperature Measuring of Magnetic Components Hello EMC-PSTCers, I wonder if anyone knows of the method of measuring temperature limits on magnetic components. I happen to get involved in this and found that my results are different than the vendors result by as much as 10-15 degrees on measuring on a same magnetic component. Even applying the thermocouple to different location on a coil seems to give you different results. Is there a method that I should be following to measure temperature with thermocouples methods, not change of resistance, on magnetic parts such as transformers, coils, etc.? Thanks, *** Kamran Mohajer DSL Compliance Lead Cisco Systems, Inc. Phone(408)-525-6121 Fax(408)527-0495 kmoha...@cisco.com *** - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
RE: Temperature Measuring of Magnetic Components
Kamran, When UL or Intertek does safety testing (UL 1950, IEC 60950) on one of our units that has coils or transformers in it they apply the thermocouples to the top (highest) horizontal surface of the coil or transformer for their temperature rise (heating) tests. I can usually find the remnants of the glue they use to attach the thermocouples on the top of the parts. On a recent unit from UL with a transformer comprised of two coils standing on end side by side, they placed thermocouples on the top horizontal surface of both coils. The magnetic parts in our equipment are rather small, less than two inches on a side. I would imagine larger magnetic components may require more thermocouples. I figure they use the top surface since heat rises it is likely to be the hottest spot. In my opinion it would make sense to use whatever method the NRTLs use and not worry too much about how the vendors do it. Although not definitive I hope this offers some insight. Kurt Andrews Compliance Engineer Tracewell Systems, Inc. 567 Enterprise Dr. Westerville, OH 43081 Ph. 614-846-6175 Fax 614-846-7791 Email: kandr...@tracewell.com -Original Message- From: Kamran Mohajer [SMTP:kmoha...@cisco.com] Sent: Tuesday, August 24, 1999 5:50 PM To: emc-p...@ieee.org Subject:Temperature Measuring of Magnetic Components Hello EMC-PSTCers, I wonder if anyone knows of the method of measuring temperature limits on magnetic components. I happen to get involved in this and found that my results are different than the vendors result by as much as 10-15 degrees on measuring on a same magnetic component. Even applying the thermocouple to different location on a coil seems to give you different results. Is there a method that I should be following to measure temperature with thermocouples methods, not change of resistance, on magnetic parts such as transformers, coils, etc.? Thanks, *** Kamran Mohajer DSL Compliance Lead Cisco Systems, Inc. Phone(408)-525-6121 Fax(408)527-0495 kmoha...@cisco.com *** - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
RE: CE Marking requirements
Dear Michael, For European requirements, you have to read the EN55022 and its Amendments 1 and 2. In the Amendment1, the chapter 9.1 explain what you have to do with your mother board. You have to test it in a commercial unit (classB) and if the test results are OK, then you can affix the CE marking on your board. Pierre Selva Laboratory responsible EMC and Safety laboratory SMEE Actions MesuresPh : 33 4 76 65 76 50 ZI des Blanchisseries Fx : 33 4 76 66 18 30 38500 VOIRON - France e-mail : actionsmesu...@compuserve.com -Original Message- From: michael.garret...@radisys.com [SMTP:michael.garret...@radisys.com] Sent: Tuesday, August 24, 1999 10:44 PM To: emc-p...@ieee.org Subject:CE Marking requirements Well group, if you care to help out another American confused by the specific requirements for Europe, I would appreciate it. I seem to be getting varying stories from different test houses as to what is required for one of our products. These are big enough players that pitting one against another is not something I want to undertake at this point. We currently manufacture a motherboard which is sold both by itself and with a chassis which includes power supply, hard drive and floppy. We are currently going through our internal EMC validation to ensure that we meet both FCC Class B and EN 55022 Class B levels. Our experience on previous products has been if we clear emissions, we haven't had problems in other areas, but we'll be testing to EN 55024 of immunity, as well. The issue arises when we discuss testing of the system versus testing of the motherboard alone. Within the US, the FCC regulations permit an additional 6dB margin for open chassis measurement, so long as those frequencies fall back within the class B levels with the cover on. This does not appear to be a problem for our product. We have been told by different parties that for Europe, (a) there is no requirement to test open chassis and that we can CE mark the board as compliant as long as we have shown that it can meet the class B levels within a chassis of our choosing and (b) we are still required to perform open chassis tests, however, there is no 6dB margin and the board will have to meet the EN 50022 class B levels with the cover off. We're having a little more difficulty making things work using the (b) approach. I am specifically concerned about staying far enough below the levels that we're not going to potentially pass today and fail 6 months from now due to a slight drift in tolerances of components, test equipment or test engineers' dispositions. I have the texts of the EMC directive, as well as the test requirements specified in the above documents and I'm happy to wade through them if you can point me in the right direction. I will be heading that direction in the next day or two if I don't receive a response. I'm hoping, however, that someone in the group can shave a few hours of exceptionally captivating reading from my life by pointing me in the right direction. Regards, Michael Garretson Compliance Engineer RadiSys Corporation - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: CE Marking requirements
Michael, In looking at the standard to answer your question, you should refer to Section 8.1 of the most current EN55022 (EN55022:1998/CISPR 22:1997), which was published in the OJ earlier this year and was mandatory as of January of this year. Specifically, the 10th paragraph of section 8.1 statesIn the case of printed wiring board assemblies (PWBA), separately marketed for the enhancement of divers host units, the PWBA (such as ISDN, interface, CPU, adaptor cards, etc.) shall be tested in at least one appropriate representative host unit of the PWBA manufacturer's choice so as to ensure compliance of the PWBA with the entire population of hosts in which it is intended to be installed. The host shall be a typical compliant production sample. PWBA intended to be class B shall not be tested in host which are class A. If one interprets the phrase such as ISDN, interface, CPU, adaptor cards, etc. to mean such as ISDN cards, interface cards, CPU cards, adaptor cards etc. then neither of your options would be valid. If one interprets the reference to CPU to mean motherboard, then it seems that your option a is valid. You may find further guidance in the following document: GUIDELINES ON THE APPLICATION OF COUNCIL DIRECTIVE 89/336/EEC OF 3 MAY 1989 ON THE APPROXIMATION OF THE LAWS OF THE MEMBER STATES RELATING TO ELECTROMAGNETIC COMPATIBILITY (DIRECTIVE 89/336/EEC AMENDED BY DIRECTIVES 91/263/EEC, 92/31/EEC, 93/68/EEC, 93/97/EEC) This document states that any component, which performs a direct function is considered to be an apparatus as defined by the EMC Directive and thus subject to the Directive. The most pertinent section of this document follows: 6.2.3. Components performing a direct function These are components that can be placed on the market in retail outlets for distribution and/or putting into service, fulfilling the criteria defined in 6.2.1, therefore delivering a direct function. Plug-in cards, such as smart cards or input/output modules, designed for incorporation into computers are apparatus commonly found in retail outlets, and available to the general public. Once cards of this type are inserted in a PC they perform a direct function for the user. They must therefore be considered as apparatus and are, consequently, subject to the provisions of the EMC Directive. This does not mean that they must necessarily be intrinsically compliant from the EMC point of view in all cases, if this is either impossible or impracticable . However, in such cases, they must be designed in such a way that they become fully EMC compliant (emissions and immunity) when they are installed as intended in the apparatus, in any of its possible variants and configurations, without exceptions, and used in the electromagnetic environment determined by the manufacturer. The instructions accompanying the component must clearly indicate these requirements, the pertinent limitations of use and how to comply without resorting to an EMC specialist (such components are available to non-EMC specialists, for a wide range of applications). The manufacturer has the ultimate responsibility for this decision. Similar examples of components with a direct function are: * plug-in cards for computer systems, micro-processor cards, central processing unit cards/mother boards, electronic mail cards, telecommunication cards, etc.; * programmable logic controllers; * lift controls; * electric motors (except for induction motors, see chapter 5.4); * computer disk drives; * power supply units (PSU), where they take the form of autonomous equipment; * electronic temperature controls; Perhaps the above might shorten your research time or just further confuse you. Hopefully it's the former. The full text of the above quoted guidelines are available on the internet. I've lost the link from which I got it, but perhaps someone on the list can lead you there. If you have no luck finding it, please email me directly and I'll forward you a pdf file via email attachment. Best Regards Michael J. Azar / Senior Program Manager EMC Compliance Management Group http://www.emc-turntech.com Tel: 650-988-0900 x 103 Fax: 650-988-6647 High quality EMC/Safety Consultancy and Approvals -Original Message- From: michael.garret...@radisys.com michael.garret...@radisys.com To: emc-p...@ieee.org emc-p...@ieee.org List-Post: emc-pstc@listserv.ieee.org Date: Tuesday, August 24, 1999 3:20 PM Subject: CE Marking requirements Well group, if you care to help out another American confused by the specific requirements for Europe, I would appreciate it. I seem to be getting varying stories from different test houses as to what is required for one of our products. These are big enough players that pitting one against another is not something I want to undertake at this point. We currently manufacture a motherboard which is sold both by itself and with a chassis
RE: CE Marking requirements
As far as I know, the EU has not adopted the insane FCC Class B compliance process. So there is NO procedure for marking a motherboard as a compliant unit. What you can do is test it in a system (just like the old days) and mark the motherboard based on that test ALONE. If I understand your requirement, you are looking to adopt the infamous CE+CE=CE approach. Again, this has proven NOT to work especially for emissions. Comments: (a) there is no requirement to test open chassis and that we can CE mark the board as compliant as long as we have shown that it can meet the class B levels within a chassis of our choosing. RESPONSE: There is no requirement NOR is there a process for open chassis testing. The EMC Directive (nor the guidelines) can help you here. (b) we are still required to perform open chassis tests, however, there is no 6dB margin and the board will have to meet the EN 50022 class B levels with the cover off. RESPONSE: Nonsense. There is NO open chassis test. WARNING: Be careful. The next thing the testhouse will try is the TCF route. Ugh. Thank you Charles Grasso Advisory Engineer StorageTek 1 StorageTek Drive Louisville CO 80027 M/S 4247. Tel:303-673-2908 Fax:303-661-7115 email:gra...@louisville.stortek.com RMCEMC Web Site: http://www.ewh.ieee.org/r5/denver/rockymountainemc/ -Original Message- From: michael.garret...@radisys.com [mailto:michael.garret...@radisys.com] Sent: Tuesday, August 24, 1999 2:44 PM To: emc-p...@ieee.org Subject: CE Marking requirements Well group, if you care to help out another American confused by the specific requirements for Europe, I would appreciate it. I seem to be getting varying stories from different test houses as to what is required for one of our products. These are big enough players that pitting one against another is not something I want to undertake at this point. We currently manufacture a motherboard which is sold both by itself and with a chassis which includes power supply, hard drive and floppy. We are currently going through our internal EMC validation to ensure that we meet both FCC Class B and EN 55022 Class B levels. Our experience on previous products has been if we clear emissions, we haven't had problems in other areas, but we'll be testing to EN 55024 of immunity, as well. The issue arises when we discuss testing of the system versus testing of the motherboard alone. Within the US, the FCC regulations permit an additional 6dB margin for open chassis measurement, so long as those frequencies fall back within the class B levels with the cover on. This does not appear to be a problem for our product. We have been told by different parties that for Europe, (a) there is no requirement to test open chassis and that we can CE mark the board as compliant as long as we have shown that it can meet the class B levels within a chassis of our choosing and (b) we are still required to perform open chassis tests, however, there is no 6dB margin and the board will have to meet the EN 50022 class B levels with the cover off. We're having a little more difficulty making things work using the (b) approach. I am specifically concerned about staying far enough below the levels that we're not going to potentially pass today and fail 6 months from now due to a slight drift in tolerances of components, test equipment or test engineers' dispositions. I have the texts of the EMC directive, as well as the test requirements specified in the above documents and I'm happy to wade through them if you can point me in the right direction. I will be heading that direction in the next day or two if I don't receive a response. I'm hoping, however, that someone in the group can shave a few hours of exceptionally captivating reading from my life by pointing me in the right direction. Regards, Michael Garretson Compliance Engineer RadiSys Corporation - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
RE: Concrete as an insulator???
Concrete is a lousy insulator. It is frequently used as a poor conductor in grounding systems. I think the conductivity of concrete was first described by Uffer (spelling ???) after his work on protective grounding of munitions bunkers. I can't find my copy of his paper right now so I can't quote numbers. But, with cement being so hydroscopic the conductivity will have a wide range. I have actually measured it in the (10s)Ohm / meter-sq. range in one instance Castable ceramics are much better. Used them in a prior life -- they worked well. Regards, Michael Taylor. -Original Message- From: POWELL, DOUG [mailto:doug.pow...@aei.com] Sent: Friday, August 20, 1999 3:40 PM To: EMC-PSTC (E-mail) Subject: Concrete as an insulator??? Hello all, I have a very innovative engineer who has come up with a design idea that uses concrete as an insulating compound in a very large inductor for a 200 kW switching power supply. Yup, this is the stuff you buy down at the local building supply company. He was very proud of the idea, but until he came up with it I think he was pretty desperate. I'm thinking I should make him desperate again but would like to be able to give him a clearly reasoned-out explanation. Has anyone ever had experience with using concrete or mortar in a high voltage application? What are the concerns here? It is my understanding that it does not actually dry but it cures with all the water contained inside. thanks, -doug === Douglas E. Powell, Compliance Engineer Advanced Energy Industries, Inc. 1625 Sharp Point Dr. Fort Collins, Colorado 80525 USA --- 970-407-6410 (phone) 970-407-5410 (e-fax) mailto:doug.pow...@aei.com mailto:doug.pow...@aei.com http://www.advanced-energy.com http://www.advanced-energy.com/ === - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
