Re: Need Help on Inner PCB plane for RF shielding in isolated circuit
Chris, Using a PCB layer as an RF shield. Don't forget you probably have that PCB layer cut into swiss cheese with vias, unless you used blind vias. Background: A microstrip trace will radiate off the board a certain amount - makes sense since part of its field is out in free space. A stripline should not radiate anything because it is between two ground layers, right? Wrong. A stripline in a practical PCB layout will only drop the emission around 14dB, due to all the swiss cheese that got cut into the PCB. My point is, knowing the above practical information are you sure that an RF shield made by a swiss cheese PCB layer will give you that much shielding? - Robert - Robert A. Macy, PEm...@california.com 408 286 3985 fx 408 297 9121 AJM International Electronics Consultants 619 North First St, San Jose, CA 95112 -Original Message- From: Chris Wells cdwe...@stargate.net To: EMC-PSTC Discussion Group emc-p...@majordomo.ieee.org Date: Thursday, February 21, 2002 5:45 AM Subject: Need Help on Inner PCB plane for RF shielding in isolated circuit Hi - I'm looking for some practical advise on using an inner Printed Circuit Board PCB plane tied at the corner mounting holes of the chassis as a shield from RF exposure coming in on an isolated field circuit relative to another digital logic board. Questions: a.. Must my shield layer be the bottom most inner plane to be effective? Note that the 2 board solder sides face each other. Layout wise it is very difficult to do without going to a 6 layer board - I am trying to stay with 4 if possible. b.. Would I get some capacitive bypass protection if the grounded shield plane where the top inner layer of the field circuit and the isolated field circuit common was the bottom inner plane exposed to the adjacent board? I know the field would not be blocked but the capacitive bypass to the chassis should reduce the RF intensity. c.. Would the placing of the grounded plane between the top PCB components and the Isolated common plane disturb the performance of the field circuitry? What would this do to the field circuit return path loop area? d.. Would a ground pour on the solder side of the adjacent PCB hurt or help? It would increase the capacitance between the two boards but it would reduce the loop area of the traces on the solder side of the adjacent board too. e.. PCB clearance issues within a PCB - What are the clearance/voltage rating issues within a PCB? What voltages can I support from: a.. Surface trace to inner grounded plane - Can 240VAC be supported. b.. Electrically hot via passing through the grounded plane - What inner pad clearance would one use on a 240VAC circuit? f.. What do the safety standards say? - I see that UL3111 version of IEC 61010-1 can treat the PCB as a molded void free material and so the clearance issues are not addressed. I understand that IPC has a spec on voltage ratings versus construction - I am looking for it now. Details: The circuit worked fine at 10V/M but I am now being asked to take this to 35V/M and that is somewhat of a challenge. Testing to ANSI C37.90.2 1995 25-1000 MHz. My problem area is 400-500 Mhz. I am trying to keep RF energy on field circuit from coupling over to an adjacent board and corrupting the bus of some microprocessor based logic. The two boards are only .200 apart. I have experimented with an insulated grounded shield plane placed in-between the two boards and it works great. I can withstand 50V/M WITH 80% modulation!!! Unfortunately the shield is very difficult to make for production and the cost is an issue. I am trying to put the shield into the 4 layer PCB in the area around the field circuit. The solder sides of the two boards face each other. The field circuitry has lots of through hole PCB type components and so there are leads and trace pads that are exposed on the bottom of the field PCB. I have trimmed the leads and this helps some. Even with a 6 layer board and the bottom inner layer as a grounded shield I would have the leads sticking through the shield like holes in cheese. The field circuit construction is: a.. top +5V pour plus a couple traces b.. top inner layer presently free - this is where I would like to put the grounded shield plane. c.. second inner layer (solder side) is the isolated field circuit common, d.. Bottom solder side are a number of field circuit traces. Unfortunately the free plane is not the bottom inner plane but the second from the top component side. The two boards have DC:DC and opto signal isolation on the field board relative to the adjacent logic board. The two boards and are connected at one edge of the board with a
Re: (no subject)
On Thu, 21 Feb 2002 11:28:57 -0800, you wrote: My apologies! In the last message I put a wrong address: maHordomo.. and of course the message got rejected - there just ain't no AI in my address book! snip You should be glad your address book has no AI. Our company email program is Lotus Notes, which will automatically pick an address from the corporate employee/customer/vendor address book if the name you type is incomplete. IE, typing 'Pat' instead of 'Pat Lawler'. More than once I've had to send follow-up emails to vendors and customers apologizing for the email they received that does not concern them. I finally found the menu option for this feature and turned it 'Off'! Patrick Lawler plaw...@west.net --- 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: Sanitary Standard Testing
Are you looking for a laboratory to perform the testing, or a copy of the standard so you can review the requirements? In the United States, standards for food products are controlled by the FDA (Food and Drug Administration). I found one web page you might start with: http://www.cfsan.fda.gov/~ear/prime.html On Thu, 21 Feb 2002 19:24:56 +0200, Peter Merguerian pmerguer...@itl.co.il wrote: Can anyone help identify a laboratory testing to Sanitary Standards for Level Sensing Devices for Dry Milk and Dry Milk Products, Number 50-00? Patrick Lawler plaw...@west.net --- 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
T200/T400
All, Adtran has a T200/T400 shelf platform that several companies apparently make circuit packs for. My contact at Adtran has said that it is an old industry standard pin out configuration for circuit packs, is similar to the old STD computer bus, and thinks it was originally developed by Charles Industries or maybe Western Electric (who became Charles). Does anyone have any idea what the original design spec was for this and where to possibly get copies? Any information at all would be appreciated. Mike --- 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
HP board schematic
Hi Listmembers: Would anyone be able to help me get a copy of the schematic for a plug-in RF amplifier board for an HP-8662 RF Synthesized Signal Generator? The board is designated the A4A1 Output Amplifier, there is an internal sticker that reads HP-08662-67008, and there is a section of etching that reads HP-08662-60126 C-2211-10. I have tried my internal files, but this board isn't shown on the 8662 manual that I was able to find. Thanks, Ed Ed Price ed.pr...@cubic.com Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA USA 858-505-2780 (Voice) 858-505-1583 (Fax) Military Avionics EMC Services Is Our Specialty Shake-Bake-Shock - Metrology - Reliability Analysis --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: 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
(no subject)
My apologies! In the last message I put a wrong address: maHordomo.. and of course the message got rejected - there just ain't no AI in my address book! Gabi: You will have read some more on the subject, so best of good luck to you! Bogdan. bogdan matoga wrote: Gabi: I believe that there is a basic rule which is not published anywhere: when you design something, then do it right. When transient suppressors are needed, then use the correct component, which will not depend on Paschen's Law and give predictable performance. Same for necked down fuses. When you want performance, then do it right. The above original suggestions are perfect for Mickey-Mouse-engineering. Bogdan. --- 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
New China Compulsory Certification Scheme
Here is more information on the new scheme. http://www.esimcom.com/aak2_0_1_2/simcom_about/cccmark.asp --- 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: EN 61000-3-3 A1
I read in !emc-pstc that richwo...@tycoint.com wrote (in 846BF526A205F8 4BA2B6045BBF7E9A6A01F13E61@flbocexu05) about 'EN 61000-3-3 A1', on Thu, 21 Feb 2002: Is there anyone that disagrees that limited inrush current is not a requirement under the amended standard? I think I should not fail to deny that I don't disagree with you. Or not. Inrush current DOES have to be taken into account, because of the limits on dmax and d(t). I spent a lot of time on that feature of the standard, as a member of the IEC WG responsible for it. It was very obscurely dealt with in the original standard and that has been improved greatly in the Millennium Amendment. -- 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
RE: South Korean Power System Schuko Plugs
The inability of Schuko plugs to be able to be polarized, may have something to do with the fact that German homes (at least) are supplied with 3-phase power. Some time ago this came as a surprise when a friend was showing me his new lathe he had just installed in his basement, which used a 3-phase motor. When I asked how he managed to get 3-phase power installed in his house, he gave me that what planet did you come from look, and said that this is how power is delivered to all residences there. My recollection from our conversation is that at least some of their domestic 3-phase power systems use the Delta configuration, so outlets are connected across 2 of the 3 phases. Thus, there is no neutral or polarity. I wonder if anyone can verify if they use a Delta or a Y connection? Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Allen, John [mailto:john.al...@uk.thalesgroup.com] Sent: February 21, 2002 12:32 AM To: Robert Wilson; emc-p...@majordomo.ieee.org Subject: RE: South Korean Power System Schuko Plugs Hi Folks A few years ago I worked for BSI Technical Help to Exporters and helped to update their publication World Wide Plugs and Sockets Survey - which I assume is still available from BSI (see www.bsi-global.com) I remember looking at the Korean standards for plugs and sockets:- Yes - they were/are variations of Schuko types(both with and without earthing contacts), but I also seem to remeber some NEMA (USA/Canadian) types as well. However, as part of another large exercise for a customer I reviewed many of the European wiring rules standards to identify any conventions or requirements for the polarity of wiring-up of sockets - notably those that accept the various versions of the (generally reversible) Schuko plugs and also the somewhat similar Danish, Swiss and Italian plugs. Result : there were (and presumably still are) wiring colour codes for the building wiring to these sockets - BUT NO CONVENTION AS TO WHICH COLOUR IS CONNECTED TO WHICH CONTACT TUBE OF THE SOCKET, apart (obviously) from the requirement that the Green/Yellow insulated conductor be connected to the earthing contact. Therefore you must always assume that the Line/Neutral polarity of the wall socket is random - this is also true for the French version of the socket with the earthing pin projecting out since it is only a (more recent?) variety of the type of socket which has no such pin. Thus the equipment connected to it must have some sort of double-pole disconnect device (be it a switch, or the plug itself). Double-pole fusing requirements may depend on the product standard requirements, but is effectively required where the internal wiring of the equipment cannot deal with the full prospective fault current available from the wall socket. Hope this clarifies matters. Regards John Allen Thales Bracknell, UK. --- 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
Sanitary Standard Testing
Dear All, Can anyone help identify a laboratory testing to Sanitary Standards for Level Sensing Devices for Dry Milk and Dry Milk Products, Number 50-00? This e-mail message may contain privileged or confidential information. If you are not the intended recipient, you may not disclose, use, disseminate, distribute, copy or rely upon this message or attachment in any way. If you received this e-mail message in error, please return by forwarding the message and its attachments to the sender. PETER S. MERGUERIAN Technical Director I.T.L. (Product Testing) Ltd. 26 Hacharoshet St., POB 211 Or Yehuda 60251, Israel Tel: + 972-(0)3-5339022 Fax: + 972-(0)3-5339019 Mobile: + 972-(0)54-838175 http://www.itl.co.il http://www.i-spec.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...@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
[no subject]
This e-mail message may contain privileged or confidential information. If you are not the intended recipient, you may not disclose, use, disseminate, distribute, copy or rely upon this message or attachment in any way. If you received this e-mail message in error, please return by forwarding the message and its attachments to the sender. PETER S. MERGUERIAN Technical Director I.T.L. (Product Testing) Ltd. 26 Hacharoshet St., POB 211 Or Yehuda 60251, Israel Tel: + 972-(0)3-5339022 Fax: + 972-(0)3-5339019 Mobile: + 972-(0)54-838175 http://www.itl.co.il http://www.i-spec.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...@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: EN 61000-3-3 A1
Sorry, te syntax of my question was incorrect. Let me try again. Is there anyone that disagrees with the following statement? Inrush current is a requirement under the amended standard. -Original Message- From: WOODS, RICHARD Sent: Thursday, February 21, 2002 9:55 AM To: 'emc-pstc' Subject: EN 61000-3-3 A1 There has been controversey over the intrepretation of EN61000-3-3 as to the need to consider in-rush current. HP had concluded that it was not a measurement requirement and had not included the measurement in their software. However, my reading of the new A1 indicates that measurement of in-rush current is a requirement. See, for example, the new added paragraph in clause 6.1 which says: For voltage changes caused by manual switching, equipment is deemed to comply without further testing if the maximum r.m.s. input current (including inrush current) evaluated over each 10 ms half-period between zero-crossings does not exceed 20 A, and the supply current after inrush is within a variation band of 1,5 A. Is there anyone that disagrees that limited inrush current is not a requirement under the amended standard? Richard Woods Sensormatic Electronics Tyco International --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: 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: Need Help on Inner PCB plane for RF shielding in isolated circuit
Chris, I had a thought, reading your message, that even a plain metal sheet, if it is close to a half wavelength across, has an RF hot spot in the middle. In that case, you must keep one side of the sheet (plane) cold, while the other is not. This means good grounds (UHF RF returns) at the edges. Are corners alone, enough? Following this reasoning, it seems to me your best chance of success, if you pursue the shielding route, is to put the (shield) plane on the solder side, facing the source, and route no traces (pickup loops!) on it. Put your plane between the source and the victim. However, I'd be inclined to beef up the victim's response, rather than shoehorn in a shield. For one thing, it is a pain in the neck for the board shop when you unbalance the stackup that way. May lower yield, depending on the board, unacceptably. For another, identifying and hardening a few strategic nets on the victim could be much cheaper to do. Maybe even faster; tooling not only costs, it takes time to add. Cortland PS: I haven't seen your board, of course, and it's difficult to do this work by telepathy (grin). Cortland --- 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
EN 61000-3-3 A1
There has been controversey over the intrepretation of EN61000-3-3 as to the need to consider in-rush current. HP had concluded that it was not a measurement requirement and had not included the measurement in their software. However, my reading of the new A1 indicates that measurement of in-rush current is a requirement. See, for example, the new added paragraph in clause 6.1 which says: For voltage changes caused by manual switching, equipment is deemed to comply without further testing if the maximum r.m.s. input current (including inrush current) evaluated over each 10 ms half-period between zero-crossings does not exceed 20 A, and the supply current after inrush is within a variation band of 1,5 A. Is there anyone that disagrees that limited inrush current is not a requirement under the amended standard? Richard Woods Sensormatic Electronics Tyco International --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: 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, Check out [912] Linholm, Loren W., and Plachy, Richard F., Electrostatic Gate Protection Using an Arc Gap Device, 11th Annual Proceedings Reliability Physics. Las Vegas, NV, Apr. 3-5, 1973, pp. 198-202. [1387] Wallash, Albert J. and Hughbanks, Timothy H., CapacitiveCoupling Effects in Spark Gap Devices, Electrical Overstress/ Electrostatic Discharge Symposium Proceedings/CITE, Las Vegas, NV, Sept. 27-29, 1994, pp. 273-278. These citations are from a nearly 1500-item bibliography of books, papers, articles, etc. on electrostatic discharge that I have on my webpage http://www.r-e-d-inc.com/esd-anno.htm Enjoy! John Barnes Consultant Robust Electronic Design, Inc. Lexington, KY Hoffknecht wrote: 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
Need Help on Inner PCB plane for RF shielding in isolated circuit
Hi - I'm looking for some practical advise on using an inner Printed Circuit Board PCB plane tied at the corner mounting holes of the chassis as a shield from RF exposure coming in on an isolated field circuit relative to another digital logic board. Questions: a.. Must my shield layer be the bottom most inner plane to be effective? Note that the 2 board solder sides face each other. Layout wise it is very difficult to do without going to a 6 layer board - I am trying to stay with 4 if possible. b.. Would I get some capacitive bypass protection if the grounded shield plane where the top inner layer of the field circuit and the isolated field circuit common was the bottom inner plane exposed to the adjacent board? I know the field would not be blocked but the capacitive bypass to the chassis should reduce the RF intensity. c.. Would the placing of the grounded plane between the top PCB components and the Isolated common plane disturb the performance of the field circuitry? What would this do to the field circuit return path loop area? d.. Would a ground pour on the solder side of the adjacent PCB hurt or help? It would increase the capacitance between the two boards but it would reduce the loop area of the traces on the solder side of the adjacent board too. e.. PCB clearance issues within a PCB - What are the clearance/voltage rating issues within a PCB? What voltages can I support from: a.. Surface trace to inner grounded plane - Can 240VAC be supported. b.. Electrically hot via passing through the grounded plane - What inner pad clearance would one use on a 240VAC circuit? f.. What do the safety standards say? - I see that UL3111 version of IEC 61010-1 can treat the PCB as a molded void free material and so the clearance issues are not addressed. I understand that IPC has a spec on voltage ratings versus construction - I am looking for it now. Details: The circuit worked fine at 10V/M but I am now being asked to take this to 35V/M and that is somewhat of a challenge. Testing to ANSI C37.90.2 1995 25-1000 MHz. My problem area is 400-500 Mhz. I am trying to keep RF energy on field circuit from coupling over to an adjacent board and corrupting the bus of some microprocessor based logic. The two boards are only .200 apart. I have experimented with an insulated grounded shield plane placed in-between the two boards and it works great. I can withstand 50V/M WITH 80% modulation!!! Unfortunately the shield is very difficult to make for production and the cost is an issue. I am trying to put the shield into the 4 layer PCB in the area around the field circuit. The solder sides of the two boards face each other. The field circuitry has lots of through hole PCB type components and so there are leads and trace pads that are exposed on the bottom of the field PCB. I have trimmed the leads and this helps some. Even with a 6 layer board and the bottom inner layer as a grounded shield I would have the leads sticking through the shield like holes in cheese. The field circuit construction is: a.. top +5V pour plus a couple traces b.. top inner layer presently free - this is where I would like to put the grounded shield plane. c.. second inner layer (solder side) is the isolated field circuit common, d.. Bottom solder side are a number of field circuit traces. Unfortunately the free plane is not the bottom inner plane but the second from the top component side. The two boards have DC:DC and opto signal isolation on the field board relative to the adjacent logic board. The two boards and are connected at one edge of the board with a pin header. The field circuitry in question must support at least a 2000 VAC/1minute High Pot to ground. Hope all this detail is not too overwhelming - I tried to put it all last for those who don't want to know... Any information you could share would be appreciated!! Thank you in advance. Chris Wells Senior Design Engineer Cutler-Hammer Pittsburgh Pennsylvannia - USA christopherdwe...@eaton.com
Flame rating
Dear all, In UL6500, table 14, it's stated the flammability category could be 5VA for some materials. Can somebody remember me this classification using 5VA, 5VB, ... ? and what are the equivalence (if any) with the classification defined by UL94 ? I know the classification HB, V2, V1, V0, 5V, but I cannot find this new one, which is issued, I believe, from the 60590. Many thanks, Pierre Selva eLABs (emc, safety, radio, eco-design - product regulations) 18 Rue Marceau Leyssieux 38400 SAINT MARTIN D'HERES - FRANCE Pierre SELVAPhone : 33 (0)6 76 63 02 58 Gérant Fax : 33 (0)6 61 37 87 48 e-mail : e.l...@wanadoo.fr --- 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: South Korean Power System Schuko Plugs
I read in !emc-pstc that Allen, John john.al...@uk.thalesgroup.com wrote (in 999c839e7e27d41185ec00d0b7473692024cd...@norway.int.rdel.co.u k) about 'South Korean Power System Schuko Plugs', on Thu, 21 Feb 2002: Double-pole fusing requirements may depend on the product standard requirements, but is effectively required where the internal wiring of the equipment cannot deal with the full prospective fault current available from the wall socket. In 230 V systems, the prospective short-circuit current through a wall socket may be at least as high as 500 A (but not for long, of course). This can cause costly damage other than through heating, e.g. through electromagnetic forces. For the cost of a second fuse and holder, it seems sensible to eliminate this, albeit not very probable, hazard. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk After swimming across the Hellespont, I felt like a Hero. 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
RE: South Korean Power System Schuko Plugs
Hi Folks A few years ago I worked for BSI Technical Help to Exporters and helped to update their publication World Wide Plugs and Sockets Survey - which I assume is still available from BSI (see www.bsi-global.com) I remember looking at the Korean standards for plugs and sockets:- Yes - they were/are variations of Schuko types(both with and without earthing contacts), but I also seem to remeber some NEMA (USA/Canadian) types as well. However, as part of another large exercise for a customer I reviewed many of the European wiring rules standards to identify any conventions or requirements for the polarity of wiring-up of sockets - notably those that accept the various versions of the (generally reversible) Schuko plugs and also the somewhat similar Danish, Swiss and Italian plugs. Result : there were (and presumably still are) wiring colour codes for the building wiring to these sockets - BUT NO CONVENTION AS TO WHICH COLOUR IS CONNECTED TO WHICH CONTACT TUBE OF THE SOCKET, apart (obviously) from the requirement that the Green/Yellow insulated conductor be connected to the earthing contact. Therefore you must always assume that the Line/Neutral polarity of the wall socket is random - this is also true for the French version of the socket with the earthing pin projecting out since it is only a (more recent?) variety of the type of socket which has no such pin. Thus the equipment connected to it must have some sort of double-pole disconnect device (be it a switch, or the plug itself). Double-pole fusing requirements may depend on the product standard requirements, but is effectively required where the internal wiring of the equipment cannot deal with the full prospective fault current available from the wall socket. Hope this clarifies matters. Regards John Allen Thales Bracknell, UK. -Original Message- From: Robert Wilson [mailto:robert_wil...@tirsys.com] Sent: 20 February 2002 19:17 To: emc-p...@majordomo.ieee.org Subject: RE: South Korean Power System Schuko plugs come in two basic versions. The original (larger) plug has two solid round pins for the AC interconnect, and two metal strips along the side of the plug (one on each side) that are grounding contacts. When inserting the plug, the body of the plug disappears into the socket recess BEFORE any electrical contact is made, making them far safer than the plugs used in North America. Ground contact to the side ground strips is made before any AC contact. These plugs have no polarization feature when used in German and most other European Schuko sockets. The plug can be rotated 180 degrees with no possibility of polarizing it. However, the Schuko plug had to accommodate the slightly different French AC socket. This socket is almost the same as the normal Shuko socket, but there is a ground pin that sticks OUT of the recessed socket, and inserts into a hole in the Schuko plug beside the 2 AC pins. This hole has a female contact (that is in parallel with the grounding strips along the edges of the plug). If the French ONLY be inserted one way around. The second type of Schuko plug is rather like the North American 2-prong plug (except is not nowhere near as cheap, flimsy or dangerous). It is flat and has no ground contact. There are two solid round pins, but they are made of plastic, with metal contacts ONLY at the very tips, so once again, no metal is exposed once contact is made. Bob Wilson TIR Systems Ltd. Vancouver. --- 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
List-Post: emc-pstc@listserv.ieee.org Date: 20-Feb-02 13:38:27 MsgID: OUTBOX MgTo: Gabi Hoffknecht INTERNET:gab...@simex.ca Subj: Re: Using PCB traces as transient voltage suppressor Hi, Gabi, I have a bad feeling about spark gaps on a board. There may be conductive material left on the board's surface after they fire, and if there's power across the traces, this can lead to unfortunate consequences. A few years ago, I had a current limited power source set a board on fire in my hand! (Better there, in a lab, than in a basement.) I started in EMC in computers, where no one worried about this stuff. Having been in the telecomm industry a few years, my experience is, we don't like high-voltage; we use SIDACTOR's at 70 to 350 volts, not the thousand or so volts a spark gap would take to fire. Cortland --- 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: Use of PCB Traces as Fuse and Voltage suppressor
When do you need a fuse? Level II is the only time you are allowed to lose functionality, and the requirement for THAT is, it can't catch fire or explode. I've seen trace fuses tried. The problem comes after the trace blows. You are at the mercy of your board shop, and if you use a number of them, results might not be all that repeatable. AS i said earlier, I've had a board catch fire in my hand (though not as a result of stress, but a solder splash). It is instructive. Cortland --- 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: EN61000-6-2
The nature of a CDN is that its purpose is to provide a 150 Ohm source impedance for the injected rf. The requirement is specified as an open circuit potential and a 150 Ohm source impedance. Since rf signal sources and amplifiers for our line of work have 50 Ohm source impedance, the CDN provides another 100 Ohms. If you were to load a CDN properly for calibration, you would load it with 150 Ohms. That way the spectrum analyzer is getting the benefit of some voltage division. If the open circuit limit is 10 Volts, then the injected potential into a matched load would be half that, 5 Volts, and the portion of that 5 Volts that the analyzer would see would only be 1/3, or 1.67 Volts, which would not cause damage. -- From: Mike Hopkins mhopk...@thermokeytek.com To: 'Jacob Schanker' schan...@frontiernet.net, Mike Hopkins mhopk...@thermokeytek.com, 'Colgan, Chris' chris.col...@tagmclaren.com, EMC Forum emc-p...@ieee.org Subject: RE: EN61000-6-2 Date: Wed, Feb 20, 2002, 5:14 PM I could be wrong -- need to go through the exercise and see if it makes sense Tell me if I'm missing something critical... 50ohm source, line, load and all connectors = no VSWR; adding any 50 ohm attenuator will not increase the VSWR. If any of the above is NOT 50 ohms, there will be reflections. So, since there seems to be some VSWR to start with, we need to assume one of the above is not 50 ohms. If the load is a high impedance, you are correct and adding an attenuator will make the VSWR look better from the source end (keeping in mind, the VSWR between the attenuator and load doesn't change). The attenuator in parallel with the high impedance load will bring the total impedance closer to 50 ohms -- not sure, but it may be that the larger the attenuator the better the match will become?? Have to think on that If the load is a low impedance, say 10 ohms, adding the attenuator will add impedance as far as the source is concerned, so again, the VSWR will appear to improve, and again, the VSWR between the attenuator and load remains high. Depending on the attenuator design, it also seems a bigger attenuator (more dB) will improve the VSWR more. So if I stick with that line of thinking -- adding an attenuator when the load is mis-matched will always reduce the VSWR at the source but never between the line and the load! (Obvious question: does the VSWR at the load matter?? Seems there would be some losses, and in some cases it could mean a lot, but that's for another day.) Mike Hopkins -Original Message- From: Jacob Schanker [mailto:schan...@frontiernet.net] Sent: Wednesday, February 20, 2002 4:01 PM To: Mike Hopkins; 'Colgan, Chris'; EMC Forum Subject: Re: EN61000-6-2 Mike: My experience tells me that an attenuator designed for the same impedance as the transmission line, will **always** improve the VSWR at the source, irrespective of how bad or good the load VSWR is. (It is most helpful to think in terms of reflection coefficients rather than VSWR directly, to appreciate this.) Your comment implies otherwise, and I wonder if you could expand on what you've said - perhaps an example of where it doesn't help (not a given)? Regards, Jacob Z. Schanker, P.E. 65 Crandon Way Rochester, NY 14618 Phone: 585 442 3909 Fax: 585 442 2182 j.schan...@ieee.org - Original Message - From: Mike Hopkins mhopk...@thermokeytek.com To: 'Colgan, Chris' chris.col...@tagmclaren.com; EMC Forum emc-p...@ieee.org Sent: Wednesday, February 20, 2002 1:48 PM Subject: RE: EN61000-6-2 | | Seems an attenuator COULD improve matching and VSWR if it then became a | significant part of the load impedance; it isn't a given. On the other | hand, adding the attenuator should NOT cause the VSWR to become very high | unless it is not a 50 ohm attenuator.. | | Mike Hopkins | | -Original Message- | From: Colgan, Chris [mailto:chris.col...@tagmclaren.com] | Sent: Wednesday, February 20, 2002 4:26 AM | To: EMC Forum | Subject: RE: EN61000-6-2 | | | | In my experience attenuators improve impedance matching and hence VSWR. | There must be something wrong with your set up. | | Regards | | Chris Colgan | Compliance Engineer | TAG McLaren Audio Ltd | The Summit, Latham Road | Huntingdon, Cambs, PE29 6ZU | *Tel: +44 (0)1480 415 627 | *Fax: +44 (0)1480 52159 | * Mailto:chris.col...@tagmclaren.com | * http://www.tagmclaren.com | | | -Original Message- | From: Sam Wismer [SMTP:swis...@bellsouth.net] | Sent: 19 February 2002 16:52 | To: EMC Forum | Subject: EN61000-6-2 | | Hi Group, | | EN 61000-6-2 calls for severity level 3, or 10Vrms for conducted | disturbances. This equates to 37dBm which is 7dB higher than the upper | limit my receiver will handle (during calibration of the CDN). I've tried | to use an attenuator and compensate for it in my readings, but this | creates a high VSWR. Any
Re: Use of PCB Traces as Fuse and Voltage suppressor
Our experience with gas discharge tubes was that they worked according to spec in the lab. fired perfectly around 400V like they're supposed to, but down inside of the PVC oil tank holding the 150KV isolation transformer they liked to fire at 600V+ Guess they needed photon energy to make the gas trigger or something. - Robert - Robert A. Macy, PEm...@california.com 408 286 3985 fx 408 297 9121 AJM International Electronics Consultants 619 North First St, San Jose, CA 95112 -Original Message- From: Chris Maxwell chris.maxw...@nettest.com To: bogda...@pacbell.net bogda...@pacbell.net Cc: EMC-PSTC Internet Forum emc-p...@majordomo.ieee.org List-Post: emc-pstc@listserv.ieee.org Date: Wednesday, February 20, 2002 2:15 PM Subject: RE: Use of PCB Traces as Fuse and Voltage suppressor Hi Bogdan, I'm sorry if you thought that my previous message was an endorsement for using necked down PCB traces as a fuse. I understand and share the sentiment that it is an unpredictable and probably not even cost effective solution. I was wondering why anyone would shape a PCB trace in such a way (two triangles pointing at each other with a thin trace between the points). A fuse is probably not the likely intention. A reasonable explanation may be a cut jumper. The triangles make the trace visible; while the thin trace provides an easy spot for the trace to be cut with an exacto knife which permanently removes the jumper.Another reason (suggested by a colleage) are alignment marks used by the PCB fab house to help align layers. Just to be sure... I'm not suggesting the above as design ideas. I'm just trying to figure out why anyone would do such a thing. One solution to the original problem that I haven't seen suggested is the good old air discharge tube, gas-discharge tube, gas tube ...whatever you want to call them. Of course, they aren't free (about $1 each). They are more predictable than open air terminals, they are UL/CSA recognized and they can handle some massive breakdown currents. They are available from Bourns and Sankosha USA... probably some other manufacturers as well. Chris -Original Message- From: bogdan matoga [SMTP:bogda...@pacbell.net] Sent: Wednesday, February 20, 2002 4:19 PM To: gab...@simex.ca; Chris Maxwell; emc-p...@mahordomo.ieee.org Subject: Use of PCB Traces as Fuse and Voltage suppressor Gabi: I believe that there is a basic rule which is not published anywhere: when you design something, then do it right. When transient suppressors are needed, then use the correct component, which will not depend on Paschen's Law and give predictable performance. Same for necked down fuses. When you want performance, then do it right. The above original suggestions are perfect for Mickey-Mouse-engineering. Bogdan. --- 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: Safety of Indicating LEDs
Rich and Scott - Irrespective of how any test house decides to address indicator LEDs, my discussions with TC76 members and contributing experts, including Bob Weiner and Jerome Dennis, as well as the remainder of the members at a panel discussion at the 1997 Laser Institute of America International Laser Safety Conference, it was not the intent of IEC60825-1 to apply to faceplate indicator LEDs of electrical equipment. Rather, the concern was for higher powered LEDs of up and coming technologies. It was the consensus of the aforementioned panel that the LED manufacturer's data sheets should be considered to provide adequate evidence of compliance, should the question arise. (One industry representative to the Infrared Data Association in attendance was particularly vociferous at his perception of injustice doled out to the lowly LED by IEC60825-1 and welcomed this as a step in the right direction.) It was further discussed that most LED data sheets use units of Lumens and Candela more often than W, Wcm-2, J, Jcm-2, or any other set of units found in IEC60825-1. The conversion is not always straight forward, since the measurements on data sheets aren't necessarily at the 20cm accommodation distance or using the measuring system in IEC60825-1, but if analysis supports compliance without extraordinary dalliance with the data, that the data sheets can and should be considered good enough. (Can and should are understood to not imply will or shall.) Far be it from certification houses to either be privy or care about the standards committee intent, when they are applying what amounts to a problematic standard (one hears how problems certainly didn't end with A11 to EN60825-1). There are also some certification houses that place so little faith in manufacturer's data sheets for either LEDs of diode lasers that they insist on performing wavelength measurements, in addition to power and energy measurements, with only the justification of needing to be certain, yielding uncertain value with respect to safety. I haven't heard from any TC76 member in many months, so if any members of this list are TC76 members or contributing experts, please add to this discussion. Regards, Peter L. Tarver, PE Product Safety Manager Sanmina-SCI Homologation Services peter.tar...@sanmina-sci.com -Original Message- From: Rich Nute Sent: Wednesday, February 20, 2002 10:25 AM Hi Scott: The scope of EN 60825-1 says LEDs are included whenever the word laser is used, meaning they are to be evaluated the same way lasers are. Does this apply to status indicating LEDs (non-lasing)? If so, are manufacturers expected to test every status-indicating LED on the product as if it were a laser? Yes. At least one certification house demands measurement data for each indicator LED. Emission class must be identified on the product or in the manual. (Note that emission class is determined under single-fault conditions in the driving circuit.) However, in practice, other certification houses use a get-out for indicator LEDs. Usually this is in the form of a not tested, but may be required by some authorities statement in the report. Most indicator LED manufacturers do not know of EN 60825-1, and have no idea how to test. Measurement is not easy, especially the determination of the aperture. Most indicator LEDs will open before achieving Class 2 emission levels. The above does not apply to automotive LEDs or to traffic signal LEDs. 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: 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: Use of PCB Traces as Fuse and Voltage suppressor
I read in !emc-pstc that Chris Maxwell chris.maxw...@nettest.com wrote (in 83d652574e7af740873674f9fc12dbaaf7d...@utexh1w2.gnnettest.com) about 'Use of PCB Traces as Fuse and Voltage suppressor', on Wed, 20 Feb 2002: I'm sorry if you thought that my previous message was an endorsement for using necked down PCB traces as a fuse. I understand and share the sentiment that it is an unpredictable and probably not even cost effective solution. It is an effective way of coping with the problem of protecting against a (highly improbable) almost direct short-circuit of a high-energy battery. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk After swimming across the Hellespont, I felt like a Hero. 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
Re: Using PCB traces as transient voltage suppressor
I read in !emc-pstc that Gabi Hoffknecht gab...@simex.ca wrote (in 80847F2BCE8AD511BE2F0060976AD68A03ECC8@SIMEXPDC01) about 'Using PCB traces as transient voltage suppressor', on Wed, 20 Feb 2002: 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 ? They are, or used to be, extensively used for flashover protection on TV CRT tube base boards. The board is pierced at the gap so there is no creepage. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk After swimming across the Hellespont, I felt like a Hero. 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
Re: double-pole switching and fusing
I read in !emc-pstc that Rich Nute ri...@sdd.hp.com wrote (in 200202202227.oaa19...@epgc264.sdd.hp.com) about 'double-pole switching and fusing', on Wed, 20 Feb 2002: Tables 2E and 2F are invoked only by the Note 2 to Sub-clause 2.7.4. A Note is informative, not a requirement. Yes, well, Note 2 is weasel-worded. It claims to be 'informative' but some test houses hold that if Table 2E or 2F is not observed, the 'essential requirements' of the LVD are not met. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk After swimming across the Hellespont, I felt like a Hero. 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
