RE: PFC or Harmonic Current Limitations outside Europe
IEEE 519 is a Recommended Practice. It suggests voltage distortion limits at the Point of Common Coupling based upon the customer load vs short circuit current capabillity. It has nothing to do with paroduct harmonics. It is not a regulation, but electric utilities may adopt it as a company requirement for customers to meet. John P. Wagner Regulatory Compliance Mandatory Standards AVAYA Strategic Standards. 1300 W. 120th Ave, Room B3-D16 Westminster, CO 80234-2726 Phone/Fax: (303) 538-4241 johnwag...@avaya.com -- From: Jim Eichner[SMTP:jim.eich...@xantrex.com] Reply To: Jim Eichner Sent: Friday, August 30, 2002 1:39 PM To: 'EMC-PSTC - forum' Subject: RE: PFC or Harmonic Current Limitations outside Europe John: Re the US: Is IEEE519 given force in any way? Is there any agency, body, or utility that is requiring IEEE519 compliance? Re Japan: Do you know the name/number of the trial standard and where I can find a list of what types of products it applies to? Thanks, Jim Eichner, P.Eng. Manager, Engineering Services Xantrex Technology Inc. phone: (604) 422-2546 fax: (604) 420-1591 e-mail: jim.eich...@xantrex.com web: www.xantrex.com Confidentiality Notice: This email message, including any attachments, is for the sole use of the intended recipient(s) and may contain confidential and privileged information. Any unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message. -Original Message- From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: Tuesday, August 27, 2002 11:54 PM To: emc-p...@majordomo.ieee.org Subject: Re: PFC or Harmonic Current Limitations outside Europe I read in !emc-pstc that Jim Eichner jim.eich...@xantrex.com wrote (in 67C475A5ECE7D4118AEC0002B325CAB6017681D7@BCMAIL1) about 'PFC or Harmonic Current Limitations outside Europe' on Mon, 26 Aug 2002: Can anyone provide any information on the requirements for (or lack of) PFC or harmonic current limitation now or in the future, in the following areas: 1. Japan Japan has had a 'trial standard' for some years. It is not the same as IEC/EN 61000-3-2, but is based on it. It does not apply to everything, as the EN does. 2. North America (I think I've heard rumours) There is already IEEE 519. I think it is exceedingly unlikely that USA will adopt the present edition of IEC 61000-3-2, particularly since it doesn't claim to apply to 120V 60 Hz systems. 3. Australia / New Zealand I understand that the current edition of IEC 61000-3-2 is being studied, but the level of controversy over it makes adoption unlikely. -- 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...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
Re: PCI Brackets Problems
Rick, Chomerics' Springline product line is an off-the-shelf solution: http://www.chomerics.com/products/cardcage.htm The spring-fingers on these one-piece gaskets are formed toward the rear panel instead of toward the inside, where damage due to snagging can be a problem. The only negative comment I have about this product concerns the stainless steel material. In my experience, mixing stainless steel and cold-rolled steel causes corrosion, even though the CRS is Zinc-plated. Chomerics has offered to tin-plate the SS for us. Over the years, the design group I'm in has tried various custom gaskets for this application--strips of tin-plated Be/Cu or Phosphor-Bronze spring fingers between the PCI brackets or fabric-over-foam gaskets, both of which have their challenges. It seems we've come full-circle and have settled on the above off-the-shelf solution. Good Luck, Dan X-MimeOLE: Produced By Microsoft Exchange V6.0.5762.3 content-class: urn:content-classes:message MIME-Version: 1.0 Subject: PCI Brackets Problems Date: Fri, 30 Aug 2002 08:54:09 -0600 X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: Curious about Tripp-Lite isolation transformer Thread-Index: AcJQM3jmO5hzvAL2Sl+Op3k/hH61TAAAMcqg From: rbus...@es.com To: emc-p...@majordomo.ieee.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by ruebert.ieee.org id g7UEsCC20318 X-Resent-To: Multiple Recipients emc-p...@majordomo.ieee.org X-Listname: emc-pstc X-Info: Help requests to emc-pstc-requ...@majordomo.ieee.org X-Info: [Un]Subscribe requests to majord...@majordomo.ieee.org X-Moderator-Address: emc-pstc-appro...@majordomo.ieee.org I am fighting the age old problem of PCI brackets on various PC chassis not making adequate electrical contact. Aperture leaks, especially at high frequencies, is a continual problem, to say nothing about the flimsy construction of the brackets. Has anyone had any success with the clips, gaskets and other EMI solutions? If you have any suggestions on types, or manufacturers please let me know. Thanks in advance... Rick Busche Evans Sutherland rbus...@es.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
Re: Curious about Tripp-Lite isolation transformer
What you got is exactly as stated in their specification. http://www.tripplite.com/products/product.cfm?productID=228 - Original Message - From: j...@aol.com To: emc-p...@majordomo.ieee.org Sent: Thursday, August 29, 2002 10:21 PM Subject: Curious about Tripp-Lite isolation transformer Hello All: Some of the laboratory tests that I perform require a source of AC mains power that is fully isolated from earth. To provide this function, I made a catalog purchase of a Tripp-Lite model IS-1000 isolation transformer. This unit is equipped with a grounded (3-prong) 120 VRMS plug on the AC mains cord used on the input side, and has a 3-prong AC mains socket on the isolated side. When the unit arrived, I was surprised to find that the green-wire ground on the input side was carried across to the ground pin on the AC socket of the isolated side. Furthermore, one side of the 120 VRMS socket on the output side was also tied to the green wire ground. In other words, the output of the unit is not isolated from ground, even if I use a cheater adapter to break the connection of the ground pin on the output socket. I also noted that the unit has capacitors and what appears to be a large MOV placed across the isolated output. My theory is that this type of isolation transformer is intended to provide protection from transients or noise on the AC mains. However, I can't see what protection the transformer provides, except maybe from common mode transients on the AC mains pair. Even so, I am having difficulty visualizing any scenario where a common mode surge would appear on the AC mains pair but not on the ground wire (given that in North America, one side of the AC mains pair is tied to ground at the service entrance). Is it possible that the transformer is designed with frequency-dependent coupling so that frequencies above 60 Hz do not couple well? Such a scheme would provide some degree of protection from differential noise. I am wondering if any of you are familiar with this type of isolation transformer and the applications where someone might need such a device. On the surface, I can't see what isolation benefit the transformer is providing when it is wired this way. It is relatively easy for me to modify the wiring to provide the fully floating, balanced AC output that I was seeking in the first place. The only thing I haven't decided yet is whether to leave the capacitors and MOV connected across the isolated output. If any of you are familiar with this type of isolation transformer and can explain the intended function, I would be interested to learn about it. Also, if you see any flaws in my rewiring plan, please let me know. I'm a little bit uneasy modifying a design that I don't fully understand. Joe Randolph Telecom Design Consultant Randolph Telecom, Inc. 781-721-2848 http://www.randolph-telecom.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
Re: Curious about Tripp-Lite isolation transformer
As you mention, there can be common mode to differential mode conversion at the service entrance since safety ground and neutral are tied together at that point. This will come right through the transformer to some extent. But you did mention that the transformer has a capacitor and MOV from line to neutral. These along with the leakage inductance of the transformer will provide filtering and limiting, thus transient reduction, but really no more than same capacitor and MOV and a series inductor would provide. The transformer does not address ground bounce, but that is a whole subject in inself. If everything around the device plugged into the transformer is also bouncing the same amount, then you have a system that looks like a bunch of devices in a Faraday cage, and there is little problem, except for the currents to ground via the distributed capacitance to earth ground of the various devices. Problems usually occur when you have a number of devices referenced to different grounds at different potentials during a disturbance. Note that if you have a ground strike that raises the local earth potential at the service entrance, it will raise the potential of the AC pair as well because neutral and safety ground are tied together at the service entrance. The long and the short is that the transformer can help for only a limited problem (common mode noise). Don Borowski Schweitzer Engineering Labs Pullman, WA j...@aol.com on 08/30/2002 11:06:47 AM Please respond to j...@aol.com To: Don Borowski/SEL@SEL, john...@itesafety.com cc: emc-p...@majordomo.ieee.org Subject: Re: Curious about Tripp-Lite isolation transformer In a message dated 8/30/2002, Don Borowski writes: But there is common mode supression (hot and neutral against safety ground) offered by the transformer, assuming that the capacitive coupling between the primary and secondary is minimal. ...There is one effect of a long run of bundled conductors - the disturbance (at least at frequencies above several hundred kHz) becomes a floating source at the power outlet end. The transformer will break the common mode current loop. Hi Don: Your explanation makes sense if we focus on high frequency common mode disturbances where the inductance of the ground wire is significant enough to make a difference. In this case, having the ground wire tied to one side of the AC at the service entrance does not ensure that these two wires are at the same instantaneous potential at the AC outlet on the other end of a long wire. At low frequencies, it does not appear that the isolation transformer provides any benefit for common mode noise. Regarding my surge scenario that Bob Johnson commented on, it seems that this type of isolation transformer provides only limited protection from lightning surges. Common mode surges coming in to the service entrance will be converted to differential surges when one side is tied to local earth, and these differential surges will sail right through the transformer (subject to its frequency response transfer function). On the other hand, ground strikes that raise the local earth potential at the service entrance will not be passed through on the AC pair, but they will come right through on the ground wire. While this is different from what would happen without the isolation transformer, I'm not sure it provides any added protection. In summary, it sounds as though this type of isolation transformer is primarily intended to attenuate high frequency common mode noise. Is this correct, or have I missed something? Joe Randolph Telecom Design Consultant Randolph Telecom, Inc. 781-721-2848 http://www.randolph-telecom.com In a message dated 8/30/2002, Don Borowski writes: But there is common mode supression (hot and neutral against safety ground) offered by the transformer, assuming that the capacitive coupling between the primary and secondary is minimal. ...There is one effect of a long run of bundled conductors - the disturbance (at least at frequencies above several hundred kHz) becomes a floating source at the power outlet end. The transformer will break the common mode current loop. Hi Don: Your explanation makes sense if we focus on high frequency common mode disturbances where the inductance of the ground wire is significant enough to make a difference. In this case, having the ground wire tied to one side of the AC at the service entrance does not ensure that these two wires are at the same instantaneous potential at the AC outlet on the other end of a long wire. At low frequencies, it does not appear that the isolation transformer provides any benefit for common mode noise. Regarding my surge scenario that Bob Johnson commented on, it seems that this type of isolation transformer provides only limited protection from lightning surges. Common mode surges coming in to the service entrance will be converted to differential surges when one side is tied to
RE: PCI Brackets Problems
Oooops, my reply was really relevant to Compact PCI panels, not PCI. Sorry, I just realized it. I haven't worked on designs using PCI brackets for EMC. I believe that former Instrument Specielties, now part of Laird Technologies, can help you. They are very knowledgeable in the area of shielding/gasketing, one of the best resources, and have many products for that. Neven Yup, we had the same problem on a GNIC card. We made the card and its L-shaped bracket. The card was intended for any ol' computer. The casual contact between the face of the bracket and the PC chassis was iffy at best. I put a couple of small dimples (punched slots really), on the long sides of the bracket. They were on both sides of the bracket and spaced equidistant from the top and bottom of the opening in the PC's card mounting bracket. The dimples made contact just before the end of the GNIC bracket aligned with the screw hole in the PC mounting bracket. This gave me enough force to make electrical grounding contact, and effectively cut the card opening size by 1/3. Yes, it does leave small slots between dimples, but these slots are significantly smaller than the slots that are left unintentionally between the card and the PC mounting bracket. The GNIC, at the time, had a very noisy 1 X 9 laser transceiver running at 1.25 GHz and this resolved my problem. The arrang! ement ended up being tested multiple times because of changes in transceivers, and other circuit changes but I never had any more problems with the fit. Gary -Original Message- From: rbus...@es.com [mailto:rbus...@es.com] Sent: Friday, August 30, 2002 7:54 AM To: emc-p...@majordomo.ieee.org Subject: PCI Brackets Problems I am fighting the age old problem of PCI brackets on various PC chassis not making adequate electrical contact. Aperture leaks, especially at high frequencies, is a continual problem, to say nothing about the flimsy construction of the brackets. Has anyone had any success with the clips, gaskets and other EMI solutions? If you have any suggestions on types, or manufacturers please let me know. Thanks in advance... Rick Busche Evans Sutherland rbus...@es.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: PFC or Harmonic Current Limitations outside Europe
John: Re the US: Is IEEE519 given force in any way? Is there any agency, body, or utility that is requiring IEEE519 compliance? Re Japan: Do you know the name/number of the trial standard and where I can find a list of what types of products it applies to? Thanks, Jim Eichner, P.Eng. Manager, Engineering Services Xantrex Technology Inc. phone: (604) 422-2546 fax: (604) 420-1591 e-mail: jim.eich...@xantrex.com web: www.xantrex.com Confidentiality Notice: This email message, including any attachments, is for the sole use of the intended recipient(s) and may contain confidential and privileged information. Any unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message. -Original Message- From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: Tuesday, August 27, 2002 11:54 PM To: emc-p...@majordomo.ieee.org Subject: Re: PFC or Harmonic Current Limitations outside Europe I read in !emc-pstc that Jim Eichner jim.eich...@xantrex.com wrote (in 67C475A5ECE7D4118AEC0002B325CAB6017681D7@BCMAIL1) about 'PFC or Harmonic Current Limitations outside Europe' on Mon, 26 Aug 2002: Can anyone provide any information on the requirements for (or lack of) PFC or harmonic current limitation now or in the future, in the following areas: 1. Japan Japan has had a 'trial standard' for some years. It is not the same as IEC/EN 61000-3-2, but is based on it. It does not apply to everything, as the EN does. 2. North America (I think I've heard rumours) There is already IEEE 519. I think it is exceedingly unlikely that USA will adopt the present edition of IEC 61000-3-2, particularly since it doesn't claim to apply to 120V 60 Hz systems. 3. Australia / New Zealand I understand that the current edition of IEC 61000-3-2 is being studied, but the level of controversy over it makes adoption unlikely. -- 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...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: PFC or Harmonic Current Limitations outside Europe
Joshua: Re Japan, I didn't have much luck on the JEITA website. Can you give me a specific reference (standard name/number, URL, etc.)? Also, is there a list of what types of products this requirement applies to? Thanks, Jim Eichner, P.Eng. Manager, Engineering Services Xantrex Technology Inc. phone: (604) 422-2546 fax: (604) 420-1591 e-mail: jim.eich...@xantrex.com web: www.xantrex.com Confidentiality Notice: This email message, including any attachments, is for the sole use of the intended recipient(s) and may contain confidential and privileged information. Any unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message. -Original Message- From: Joshua Wiseman [mailto:jwise...@printronix.com] Sent: Wednesday, August 28, 2002 8:34 AM To: 'Jim Eichner'; 'EMC-PSTC - forum' Subject: RE: PFC or Harmonic Current Limitations outside Europe Jim, When China converted to the CCC approval scheme they adopted the Chinese version of EN 61000-3-2. Japan has a requirement under JEITA to test harmonics at 120V while using an impedance in line. I have heard that Australia and Korea are also moving in this direction. Taiwan follows the US for the most part and I have not heard anything in this arena. I am curious to hear the responses you get on this one. Good luck. Regards, Josh Josh Wiseman EMC/Product Safety (714) 368-2737 [ mailto:jwise...@printronix.com mailto:jwise...@printronix.com ] -Original Message- From: Jim Eichner [ mailto:jim.eich...@xantrex.com mailto:jim.eich...@xantrex.com ] Sent: Monday, August 26, 2002 12:33 PM To: 'EMC-PSTC - forum' Subject: PFC or Harmonic Current Limitations outside Europe Can anyone provide any information on the requirements for (or lack of) PFC or harmonic current limitation now or in the future, in the following areas: 1. Japan 2. North America (I think I've heard rumours) 3. Australia / New Zealand 4. Any other location you are aware of where it definitely IS a requirement Thanks as always for the group's input. Regards, Jim Eichner, P.Eng. Manager, Engineering Services Xantrex Technology Inc. Mobile Power web: www.xantrex.com http://www.xantrex.com http://www.xantrex.com Any opinions expressed are those of my invisible friend, who really exists. Honest. Confidentiality Notice: This email message, including any attachments, is for the sole use of the intended recipient(s) and may contain confidential and privileged information. Any unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message. --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
Re: PCI Brackets Problems
There are several types of gaskets. The ones with a continuous ridge along the centerline (inverted V-shape) are not compliant thus they can leave slots and cause difficulties with board insertion. The spiral gaskets make good contact but tend to kink, get caught and fall out of the groove in the panels. The best ones have a series of rounded clip- like fingers along the gasket, allowing each individual contact to comply with the size/shape between two panels. Regarding material, you want to use (plated) beryllium copper. I think the kind that is best is thermally treated after it has been formed. Unfortunately the standard panels are aluminum, which is not best material regarding developing contact resistance to a different gasket material over time, due to galvanic effect/corrosion. Neven I am fighting the age old problem of PCI brackets on various PC chassis not making adequate electrical contact. Aperture leaks, especially at high frequencies, is a continual problem, to say nothing about the flimsy construction of the brackets. Has anyone had any success with the clips, gaskets and other EMI solutions? If you have any suggestions on types, or manufacturers please let me know. Thanks in advance... Rick Busche Evans Sutherland rbus...@es.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
Re: R: Telephone headsets
I read in !emc-pstc that Luigino Catello luigino.cate...@tin.it wrote (in 00a301c25046$2158dd80$be5dabd4@oemcomputer) about 'R: Telephone headsets' on Fri, 30 Aug 2002: The safety standard is the EN 60950. Why? A telephone headset is not within the scope of EN 60950, I think. EN 60065 is more applicable. -- 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...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: PCI Brackets Problems
Yup, we had the same problem on a GNIC card. We made the card and its L-shaped bracket. The card was intended for any ol' computer. The casual contact between the face of the bracket and the PC chassis was iffy at best. I put a couple of small dimples (punched slots really), on the long sides of the bracket. They were on both sides of the bracket and spaced equidistant from the top and bottom of the opening in the PC's card mounting bracket. The dimples made contact just before the end of the GNIC bracket aligned with the screw hole in the PC mounting bracket. This gave me enough force to make electrical grounding contact, and effectively cut the card opening size by 1/3. Yes, it does leave small slots between dimples, but these slots are significantly smaller than the slots that are left unintentionally between the card and the PC mounting bracket. The GNIC, at the time, had a very noisy 1 X 9 laser transceiver running at 1.25 GHz and this resolved my problem. The arrang! ement ended up being tested multiple times because of changes in transceivers, and other circuit changes but I never had any more problems with the fit. Gary -Original Message- From: rbus...@es.com [mailto:rbus...@es.com] Sent: Friday, August 30, 2002 7:54 AM To: emc-p...@majordomo.ieee.org Subject: PCI Brackets Problems I am fighting the age old problem of PCI brackets on various PC chassis not making adequate electrical contact. Aperture leaks, especially at high frequencies, is a continual problem, to say nothing about the flimsy construction of the brackets. Has anyone had any success with the clips, gaskets and other EMI solutions? If you have any suggestions on types, or manufacturers please let me know. Thanks in advance... Rick Busche Evans Sutherland rbus...@es.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
Re: Telephone headsets
I read in !emc-pstc that Chris K. Poore chr...@percept.com wrote (in kgeakhgkelfiikpbjhaiaejnccaa.chr...@percept.com) about 'Telephone headsets' on Fri, 30 Aug 2002: Is there a safety standard that we should use that is specific to these telephone headsets for EU compliance? What is the application? It is almost certain that, whether it is for household or professional use, the relevant standard is IEC 60065. But not if it's for *direct* connection to the public telephone system. -- 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...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
Re: I wonder about some comments in IEC 664-1:1992
I read in !emc-pstc that Michael Jang mich...@certitek.com wrote (in poeoldooigidlejlplfpoejfcjaa.mich...@certitek.com) about 'I wonder about some comments in IEC 664-1:1992' on Fri, 30 Aug 2002: I don't have a standard (IEC 664-1:1992). That says it all, doesn't it. The current edition is dated 2000-04-28. -- 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...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
Re: requirements for ITE power cords
Actually, the rule (Article 210-22 of the NEC) has nothing to do with protecting the plugs or the wiring. The 80% rule is there to make sure the branch circuit overcurrent protective device (fuse or CB) doesn't overheat. - Original Message - From: Robert Johnson john...@itesafety.com To: emc-p...@majordomo.ieee.org Sent: Thursday, August 29, 2002 10:50 PM Subject: RE: requirements for ITE power cords Sorry to knock your substantially built comment, but the derating is not based on the plug. In fact the 15 and 20 amp plugs are the same construction with different configuration. Both can be used at full rating. The circuit they are used in contains the limitation. The derating on North American circuits is based on thermal considerations. The derating (80% of rated load) applies to all continuous loads which are defined as over 3 hours. ITE is considered continuous by default. The long term degradation of wire insulation is related to temperature and time. Given considerations such as neighboring conductors, thermal insulation, current, duration, wire gauge, etc, this is one way the code allows for higher short term loads. Bob Johnson ITE Safety -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org] On Behalf Of John Allen Sent: Thursday, August 29, 2002 5:28 PM To: richwo...@tycoint.com; emc-p...@majordomo.ieee.org Subject: Re: requirements for ITE power cords Hi Folks Sorry to be late in replying on this one - and not really trying to disagree - but I think you will find that the 125% rule is a North American convention and also followed by countries which use similar installation practice (i.e. that have plugs with quite small blades/pins!). The same rule does not - to the best of my knowledge - apply in Europe ( certainly not in the UK) and other countries that follow European installation practice where derating is not required as our plugs are more substantially built! Therefore we can use a 13 (UK) or 16A (Europe) cable and 13A or 16A plug on an equipment rated at 13A/16A respectively, e.g: re it applies in respect of the EN60950 standard. Regards John Allen - Original Message - From: richwo...@tycoint.com To: emc-p...@majordomo.ieee.org Sent: Thursday, August 15, 2002 11:59 AM Subject: RE: requirements for ITE power cords George, the ITE safety standards require that the plug be rated for at least 125% of the equipment rating. I believe that the US National Electrical Code has the same requirement. Richard Woods Sensormatic Electronics Tyco International -Original Message- From: George Stults [mailto:george.stu...@watchguard.com] Sent: Wednesday, August 14, 2002 6:28 PM To: 'emc-p...@majordomo.ieee.org' Subject: requirements for ITE power cords Hello Group, Recently my purchasing department asked me to recommend standards for power cords. These are detachable power cords for ITE equipment, both 3-wire and 2-wire. Typically the cords are marked with one or more of CSA, UL, (Dentori T). The ones we get are typically rated from 6 to 10 times the required current for a given product. My question is, are there required or recommended power cord design margins for current, voltage, power, temperature range, insulation, etc. spelled out in IEC/EN 60950 or UL1950 or MIL-HDBK 217 or elsewhere? Thanks in advance George Stults --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and
Re: Curious about Tripp-Lite isolation transformer
In a message dated 8/30/2002, Don Borowski writes: But there is common mode supression (hot and neutral against safety ground) offered by the transformer, assuming that the capacitive coupling between the primary and secondary is minimal. ...There is one effect of a long run of bundled conductors - the disturbance (at least at frequencies above several hundred kHz) becomes a floating source at the power outlet end. The transformer will break the common mode current loop. Hi Don: Your explanation makes sense if we focus on high frequency common mode disturbances where the inductance of the ground wire is significant enough to make a difference. In this case, having the ground wire tied to one side of the AC at the service entrance does not ensure that these two wires are at the same instantaneous potential at the AC outlet on the other end of a long wire. At low frequencies, it does not appear that the isolation transformer provides any benefit for common mode noise. Regarding my surge scenario that Bob Johnson commented on, it seems that this type of isolation transformer provides only limited protection from lightning surges. Common mode surges coming in to the service entrance will be converted to differential surges when one side is tied to local earth, and these differential surges will sail right through the transformer (subject to its frequency response transfer function). On the other hand, ground strikes that raise the local earth potential at the service entrance will not be passed through on the AC pair, but they will come right through on the ground wire. While this is different from what would happen without the isolation transformer, I'm not sure it provides any added protection. In summary, it sounds as though this type of isolation transformer is primarily intended to attenuate high frequency common mode noise. Is this correct, or have I missed something? Joe Randolph Telecom Design Consultant Randolph Telecom, Inc. 781-721-2848 http://www.randolph-telecom.com
R: Telephone headsets
For your telephone headsets you have to follow the RTTE directive not the LVD. The safety standard is the EN 60950. L. Catello Compliace Engineer ITALTEL-Italy - Original Message - From: Chris K. Poore chr...@percept.com To: EMC-PSTC emc-p...@majordomo.ieee.org Sent: Friday, August 30, 2002 4:02 PM Subject: Telephone headsets We have some telephone headsets that we want to CE Mark, but are not sure what safety standard to use. Additionally, I don't see any category under the CE Marking directive that would be entirely applicable. The LVD seems most logical, except that the input voltage to the headsets is well below the 75DC, 50AC cutoff. The headsets will connect to an OEM audio amplifier that has been evaluated to the LVD, and seems to contain all the necessary isolation (we are not even selling the amplifier). The primary reason for wanting to CE Mark is because a competitor is doing it. Is there a safety standard that we should use that is specific to these telephone headsets for EU compliance? Thanks, Chris K. Poore Staff Compliance Engineer - Percept Technology Labs, Inc. 4735 Walnut #E Boulder, CO 80301 303-444-7480 ext. 113 303-444-1565 Fax mailto:chr...@percept.com http://www.percept.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: Telephone headsets
Chris, the CE marking indicates that the product complies with all applicable directives. The only two directives that might apply is the LV and EMC directives. However, the LVD does not apply since the working voltages are low. The EMC directive would apply if your equipment is likely to cause interference or likely to be susceptable to interference. I tend to believe that your equipment is not likely to cause interference, but it might be susceptable to magnetic fields. So some immunity requirements may apply. If so, your Declaration of Conformity would only claim compliance with the EMC Directive. If the EMC Directive does not apply, then no Declaration or CE marking is required. Richard Woods Sensormatic Electronics Tyco International -Original Message- From: Chris K. Poore [mailto:chr...@percept.com] Sent: Friday, August 30, 2002 10:02 AM To: EMC-PSTC Subject: Telephone headsets We have some telephone headsets that we want to CE Mark, but are not sure what safety standard to use. Additionally, I don't see any category under the CE Marking directive that would be entirely applicable. The LVD seems most logical, except that the input voltage to the headsets is well below the 75DC, 50AC cutoff. The headsets will connect to an OEM audio amplifier that has been evaluated to the LVD, and seems to contain all the necessary isolation (we are not even selling the amplifier). The primary reason for wanting to CE Mark is because a competitor is doing it. Is there a safety standard that we should use that is specific to these telephone headsets for EU compliance? Thanks, Chris K. Poore Staff Compliance Engineer - Percept Technology Labs, Inc. 4735 Walnut #E Boulder, CO 80301 303-444-7480 ext. 113 303-444-1565 Fax mailto:chr...@percept.com http://www.percept.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
Radiated emission - power cable layout
Hi all, Assume you are going to power three units from a power distribution box. You might have two scenarios: 1. Route one cable to the first unit, from that unit you route a new power cable to the next unit, and so on (serial connections) 2. Three separate power cables, one cable to each unit (parallel). Whats best practice for EMC ?? I assume you have to make a lot of assumptions regarding the cable layout and the installation. But are there any basic rules for such cable distribution that we should be aware of regarding Radiated emission ? Best regards Amund Westin, Oslo, NORWAY --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
Ampacity - PCB ratings
Mark Gill asked: I have a question for the group on the effects of temperature rating and deterioration. If a pcb is rated X degrees C, and the sizing of the power traces on an inner layer is such that the pcb temperature is now (X-1) degrees C, What effect does this have on the longevity of the pcb? A while back, I was a test engineer in the PCB category. Generally, the substrate material (and in fact, most thermoplastic and thermoset materials) obtained temperature ratings based on a process outlined in the UL 746 series of standards: The manufacturer of the substrate estimated a tempertature rating for the material at a minimum thickness. Based on that temperature rating, three oven aging temperatures roughly 10 degrees C apart were assigned to simulate long term aging. For example, if the hoped-for temp rating was 110 degrees C, the board substrates were placed in three separate ovens at about 150, 160 and 170. Certain physical characteristics (electrical and mechanical) of the materials were first measured on as-received samples - including dielectric withstand breakdown point, tensile strength, and others. After several months of aging at the higher temperatures, samples were retested. If the physical characteristics had not degraded to 50% of the original values, the test continued. If they had, the test stopped at that aging temp, and the time was recorded. Of course, the higher temp samples usually reached the 50% values first, then the middle, then the lower. At the conclusion of the test - when all three temperature samples reached 50% breakdown, curves were drawn based on time and temperature, then extrapolated out to the 20 year mark. If, at the 20 year mark, the time temperature curve was within a few degrees of the expected temperature rating, the material then received the requested rating. Sometimes the rating was adjusted upwards or downwards accordingly, other times the test was re-run at newly calibrated aging temperatures. It is a lengthy and expensive process. I don't know how much this helps you, but the overall philosophy on temperature rating of laminates is that after operating for 20 years at the rated temperature, the critical physical properties of the material should not have degraded to below 50% of the unaged sample. Greg Galluccio www.productapprovals.com A HREF=www.soundsurfr.com /A
RE: EN60950-1 Sect 2.5 Limited Power sources
1. What is the correct method to test for a Limited Power source in determining what enclosure is required? The Isc limits must be met regardless of the load, not only at 30a or 8a. You need to do sufficient testing to satisfy yourself it will comply in general. In this case you have demonstrated a failure. 2. If a fire enclosure was needed what is the minimum plastic rating i.e. 94V0, V1 or what? 94V-0 is not mentioned in the standard. Requirements would be for 5-V, V-1 or other requirements in clause 4.7.3.2 if a fire enclosure is required. 3. I cannot put a 5A fuse in the product, the lab says that the overcurrent protective device must be outwith the non-fire enclosure in order to stop the non compliant energy source entering the enclosure. Is this correct? Somewhat. The portion of the circuit not meeting the requirement is the part which needs the enclosure. Note that this does not mean the entire product. You can provide a fire enclosure around a small entry area and not include the rest of the product. 4. Similarly, I cannot use a resettable fuse in the product to meet these requirements? You may meet the requirements with fuse, PTC or other limiter. 5. Does the PTC used in the power supply need to meet the IEC 60730-1? Not if you can assure the requirements relevant to the application are met by your own testing. See clause 1.5.2. Bob Johnson ITE Safety -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org] On Behalf Of Alex McNeil Sent: Friday, August 30, 2002 5:25 AM To: 'emc-p...@majordomo.ieee.org' Subject: EN60950-1 Sect 2.5 Limited Power sources Hi group, I have a query on the understanding of the above section. I thought I fully understood it until I used a different lab for Product Safety Compliance testing (both accredited!). We use a linear (basically a transformer with a PTC thermistor) class II SELV O/P stand alone power supply rated 10Vac, 5A. One of the labs tested the O/P Isc with a direct application of the sc. The other lab tested the O/P Isc by applying a load of 8A. The results were therefore interpreted differently. Isc (direct) = 30A falling to 0A within 30secs. Considered a PASS (8A for 1min) Isc (8A load) = 8A for 2mins. Considered a FAIL (8A 1min) This has a crucial bearing on whether I need a fire enclosure or not for my all plastic enclosure! 1. What is the correct method to test for a Limited Power source in determining what enclosure is required? 2. If a fire enclosure was needed what is the minimum plastic rating i.e. 94V0, V1 or what? 3. I cannot put a 5A fuse in the product, the lab says that the overcurrent protective device must be outwith the non-fire enclosure in order to stop the non compliant energy source entering the enclosure. Is this correct? 4. Similarly, I cannot use a resettable fuse in the product to meet these requirements? 5. Does the PTC used in the power supply need to meet the IEC 60730-1? I would very much appreciate clarification on this matter. THANKS!! Kind Regards Alex McNeil Principal Engineer Tel: +44 (0)131 479 8375 Fax: +44 (0)131 479 8321 email: alex.mcn...@ingenicofortronic.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list attachment: Robert Johnson.vcf
PCI Brackets Problems
I am fighting the age old problem of PCI brackets on various PC chassis not making adequate electrical contact. Aperture leaks, especially at high frequencies, is a continual problem, to say nothing about the flimsy construction of the brackets. Has anyone had any success with the clips, gaskets and other EMI solutions? If you have any suggestions on types, or manufacturers please let me know. Thanks in advance... Rick Busche Evans Sutherland rbus...@es.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
Re: Curious about Tripp-Lite isolation transformer
Joe- I think you have got most of the points right. But there is common mode supression (hot and neutral against safety ground) offered by the transformer, assuming that the capacitive coupling between the primary and secondary is minimal. Note that this common mode signal is in fact differential mode with the safety ground being one conductor and the hot and neutral being the other conductor. The fact that the conductors run together in a bundle, and that the neutral and ground are connected together at the service entrance does not change the nature of the disturbance. There is one effect of a long run of bundled conductors - the disturbance (at least at frequencies above several hundred kHz) becomes a floating source at the power outlet end. The transformer will break the common mode current loop. But the safety ground wire will not necessarily be quiet relative to local earth ground. In fact, the safety ground could be made quite noisy by capacitively bypassing hot and neutral to local earth ground! On the other hand, the transformer would not serve for what I personally (as a hobby) use isolation transformers for - servicing TVs and old radios. In the case of the TVs, the horizontal output section is powered from a bridge rectifier connected to the power line. This circuitry is always hot, and needs to be powered from a floating AC power source. The old radios in question do not have transformers, so their circuits are hot. Not a good place to be probing with a grounded oscilloscope probe! Don Borowski Schweitzer Engineering Labs Pullman, WA For wiring not in conduits, j...@aol.com on 08/29/2002 07:21:06 PM Please respond to j...@aol.com To: emc-p...@majordomo.ieee.org cc:(bcc: Don Borowski/SEL) Subject: Curious about Tripp-Lite isolation transformer Hello All: Some of the laboratory tests that I perform require a source of AC mains power that is fully isolated from earth. To provide this function, I made a catalog purchase of a Tripp-Lite model IS-1000 isolation transformer. This unit is equipped with a grounded (3-prong) 120 VRMS plug on the AC mains cord used on the input side, and has a 3-prong AC mains socket on the isolated side. When the unit arrived, I was surprised to find that the green-wire ground on the input side was carried across to the ground pin on the AC socket of the isolated side. Furthermore, one side of the 120 VRMS socket on the output side was also tied to the green wire ground. In other words, the output of the unit is not isolated from ground, even if I use a cheater adapter to break the connection of the ground pin on the output socket. I also noted that the unit has capacitors and what appears to be a large MOV placed across the isolated output. My theory is that this type of isolation transformer is intended to provide protection from transients or noise on the AC mains. However, I can't see what protection the transformer provides, except maybe from common mode transients on the AC mains pair. Even so, I am having difficulty visualizing any scenario where a common mode surge would appear on the AC mains pair but not on the ground wire (given that in North America, one side of the AC mains pair is tied to ground at the service entrance). Is it possible that the transformer is designed with frequency-dependent coupling so that frequencies above 60 Hz do not couple well? Such a scheme would provide some degree of protection from differential noise. I am wondering if any of you are familiar with this type of isolation transformer and the applications where someone might need such a device. On the surface, I can't see what isolation benefit the transformer is providing when it is wired this way. It is relatively easy for me to modify the wiring to provide the fully floating, balanced AC output that I was seeking in the first place. The only thing I haven't decided yet is whether to leave the capacitors and MOV connected across the isolated output. If any of you are familiar with this type of isolation transformer and can explain the intended function, I would be interested to learn about it. Also, if you see any flaws in my rewiring plan, please let me know. I'm a little bit uneasy modifying a design that I don't fully understand. Joe Randolph Telecom Design Consultant Randolph Telecom, Inc. 781-721-2848 http://www.randolph-telecom.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher:
RE: Curious about Tripp-Lite isolation transformer
The transformer generates what the code call a separately derived system. Typically such circuits are grounded (earthed). For US requirements see the National Electrical Code articles 250.21 and 250.22. The isolation transformer reduces common mode (supply vs ground) noise. That is its primary purpose. They try to have very low capacitive coupling primary to secondary. You did not explain your reason for purchase and use. If it is for prevention of electric shock, a GFI (RCD) can serve the purpose. If you are trying to make scope measurements not referenced to ground, then use differential measurement rather than float the subject or the scope. Regarding: I am having difficulty visualizing any scenario where a common mode surge would appear on the AC mains pair but not on the ground wire (given that in North America, one side of the AC mains pair is tied to ground at the service entrance). The surge voltage you are describing is on the ground wire relative to what? The ground wire? The ether? The isolation transformer has reduced the transients on the supply (phase and neutral) relative to the ground. Understand there is no universal reference. Ground or earth is meant to be a common equipotential environment and is only significant relative to the planet when you are standing on it and making it part of your environment. A good understanding of the Faraday cage is useful when understanding earthing or grounding. Bob Johnson ITE Safety -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org] On Behalf Of j...@aol.com Sent: Thursday, August 29, 2002 10:21 PM To: emc-p...@majordomo.ieee.org Subject: Curious about Tripp-Lite isolation transformer Hello All: Some of the laboratory tests that I perform require a source of AC mains power that is fully isolated from earth. To provide this function, I made a catalog purchase of a Tripp-Lite model IS-1000 isolation transformer. This unit is equipped with a grounded (3-prong) 120 VRMS plug on the AC mains cord used on the input side, and has a 3-prong AC mains socket on the isolated side. When the unit arrived, I was surprised to find that the green-wire ground on the input side was carried across to the ground pin on the AC socket of the isolated side. Furthermore, one side of the 120 VRMS socket on the output side was also tied to the green wire ground. In other words, the output of the unit is not isolated from ground, even if I use a cheater adapter to break the connection of the ground pin on the output socket. I also noted that the unit has capacitors and what appears to be a large MOV placed across the isolated output. My theory is that this type of isolation transformer is intended to provide protection from transients or noise on the AC mains. However, I can't see what protection the transformer provides, except maybe from common mode transients on the AC mains pair. Even so, I am having difficulty visualizing any scenario where a common mode surge would appear on the AC mains pair but not on the ground wire (given that in North America, one side of the AC mains pair is tied to ground at the service entrance). Is it possible that the transformer is designed with frequency-dependent coupling so that frequencies above 60 Hz do not couple well? Such a scheme would provide some degree of protection from differential noise. I am wondering if any of you are familiar with this type of isolation transformer and the applications where someone might need such a device. On the surface, I can't see what isolation benefit the transformer is providing when it is wired this way. It is relatively easy for me to modify the wiring to provide the fully floating, balanced AC output that I was seeking in the first place. The only thing I haven't decided yet is whether to leave the capacitors and MOV connected across the isolated output. If any of you are familiar with this type of isolation transformer and can explain the intended function, I would be interested to learn about it. Also, if you see any flaws in my rewiring plan, please let me know. I'm a little bit uneasy modifying a design that I don't fully understand. Joe Randolph Telecom Design Consultant Randolph Telecom, Inc. 781-721-2848 http://www.randolph-telecom.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and
Re: Curious about Tripp-Lite isolation transformer
In a message dated 8/30/2002, Chris Maxwell writes: Most isolation transformers have a non-magnetic, metal shield between the primary and secondary. The shield does not appreciably degrade the transformer's magnetic coupling at 60Hz; however, it does attenuate the high frequency differential noise passed from primary to secondary. Hi Chris: Thanks for your response. This transformer does indeed have a grounded shield between the primary and secondary. I guess I don't know enough about transformer design to understand why the shield would attenuate differential noise. I can certainly see how it would reduce common mode coupling at high frequencies, since the grounded shield will reduce the inter-winding capacitance. Do you know of some typical applications for this type of isolation transformer? There must be enough demand for them, since Tripp-Lite and a few other manufacturers offer them as a catalog item. In the mean time, I plan to modify the wiring as I described previously to obtain a floating, ungrounded AC supply. Joe Randolph Telecom Design Consultant Randolph Telecom, Inc. 781-721-2848 http://www.randolph-telecom.com
Telephone headsets
We have some telephone headsets that we want to CE Mark, but are not sure what safety standard to use. Additionally, I don't see any category under the CE Marking directive that would be entirely applicable. The LVD seems most logical, except that the input voltage to the headsets is well below the 75DC, 50AC cutoff. The headsets will connect to an OEM audio amplifier that has been evaluated to the LVD, and seems to contain all the necessary isolation (we are not even selling the amplifier). The primary reason for wanting to CE Mark is because a competitor is doing it. Is there a safety standard that we should use that is specific to these telephone headsets for EU compliance? Thanks, Chris K. Poore Staff Compliance Engineer - Percept Technology Labs, Inc. 4735 Walnut #E Boulder, CO 80301 303-444-7480 ext. 113 303-444-1565 Fax mailto:chr...@percept.com http://www.percept.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: Curious about Tripp-Lite isolation transformer
Joe, Most isolation transformers have a non-magnetic, metal shield between the primary and secondary. The shield does not appreciably degrade the transformer's magnetic coupling at 60Hz; however, it does attenuate the high frequency differential noise passed from primary to secondary. The ground scheme that you mention (Earth carried through and tied to secondary nuetral) is very common (no pun intended) in isolation transformers.The theory here is that the secondary will present a power outlet to the load that looks just like a normal outlet. In the US, 120VAC neutral and Earth are bonded together at the building electrical entrance. So, in most 120VAC sockets, you would have continuity from Neutral to Earth, just like the output of your isolation transformer. Of course, if you are using the isolation transformer to isolate and step up to 230VAC; then the nuetral/Earth connection in your isolation transformer may not simulate the real world. This is due to the fact that many 220/230/240VAC circuits do not have a nuetral bonded to ground. Chris Maxwell | Design Engineer - Optical Division email chris.maxw...@nettest.com | dir +1 315 266 5128 | fax +1 315 797 8024 NetTest | 6 Rhoads Drive, Utica, NY 13502 | USA web www.nettest.com | tel +1 315 797 4449 | -Original Message- From: j...@aol.com [SMTP:j...@aol.com] Sent: Thursday, August 29, 2002 10:21 PM To: emc-p...@majordomo.ieee.org Subject: Curious about Tripp-Lite isolation transformer Hello All: Some of the laboratory tests that I perform require a source of AC mains power that is fully isolated from earth. To provide this function, I made a catalog purchase of a Tripp-Lite model IS-1000 isolation transformer. This unit is equipped with a grounded (3-prong) 120 VRMS plug on the AC mains cord used on the input side, and has a 3-prong AC mains socket on the isolated side. When the unit arrived, I was surprised to find that the green-wire ground on the input side was carried across to the ground pin on the AC socket of the isolated side. Furthermore, one side of the 120 VRMS socket on the output side was also tied to the green wire ground. In other words, the output of the unit is not isolated from ground, even if I use a cheater adapter to break the connection of the ground pin on the output socket. I also noted that the unit has capacitors and what appears to be a large MOV placed across the isolated output. My theory is that this type of isolation transformer is intended to provide protection from transients or noise on the AC mains. However, I can't see what protection the transformer provides, except maybe from common mode transients on the AC mains pair. Even so, I am having difficulty visualizing any scenario where a common mode surge would appear on the AC mains pair but not on the ground wire (given that in North America, one side of the AC mains pair is tied to ground at the service entrance). Is it possible that the transformer is designed with frequency-dependent coupling so that frequencies above 60 Hz do not couple well? Such a scheme would provide some degree of protection from differential noise. I am wondering if any of you are familiar with this type of isolation transformer and the applications where someone might need such a device. On the surface, I can't see what isolation benefit the transformer is providing when it is wired this way. It is relatively easy for me to modify the wiring to provide the fully floating, balanced AC output that I was seeking in the first place. The only thing I haven't decided yet is whether to leave the capacitors and MOV connected across the isolated output. If any of you are familiar with this type of isolation transformer and can explain the intended function, I would be interested to learn about it. Also, if you see any flaws in my rewiring plan, please let me know. I'm a little bit uneasy modifying a design that I don't fully understand. Joe Randolph Telecom Design Consultant Randolph Telecom, Inc. 781-721-2848 http://www.randolph-telecom.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: EN60950-1 Sect 2.5 Limited Power sources
Alex, 1. What is the correct method to test for a Limited Power source in determining what enclosure is required? Peter: The correct method for inherently limited power source is to measure the output current (Isc) after 60 seconds of operation with the load adjusted to maintain the Isc current limit (8.0 A). In your case the PTC serves as the impedance limiting the current flow. I do not understand why the Isc (8A load) lab failed you since you did not exceed the 8A and the result should have been acceptable. 2. If a fire enclosure was needed what is the minimum plastic rating i.e. 94V0, V1 or what? Peter: Sounds like you have a movable equipment with a total mass 18 kg. For a fire enclosure, you need a 94V-1 enclosure or one that can withstsnd the tests of Clause A.2 3. I cannot put a 5A fuse in the product, the lab says that the overcurrent protective device must be outwith the non-fire enclosure in order to stop the non compliant energy source entering the enclosure. Is this correct? Peter: I assume you mean you cannot put a max. 5 A or less to meet the Isc of less than or = 1000/Uoc for power sources not inherently limited. The rated current values of the overcurrent protector in Table 9 are for devices located in the secondary. If the fuse is located in the primary, the max values of Table 9 should be adjusted based on the pri/sec windings turns ratio. For example, if a transformer has a 5:1 turns ratio, then the max values of the rated currents for the overcurrent devices in the primary should be adjusted to 1/5 of the values shown, or in your case 1/5 (5 A) = 1 A The fuse and transformer must be within the fire enclosure. You can get away with it if your fuse is within an appliance inlet in the primary, your leads are PVC, TFE, PTFE, FEP or neoprene and the transformer itself (except laminations) has its own fire enclosure. There are many transformer constructions with bobbin/cover constructions which would meet the fire enclosure requirements. For reference, see 4.7.2.1 (parts requiring fire enclosures) and 4.7.2.2 (parts not requiring fire enclosures). 4. Similarly, I cannot use a resettable fuse in the product to meet these requirements? Peter: You have a PTC within the transformer; make sure it is approved and meets the tests in IEC 60730-1, clauses 15, 17, J15 and J17. 5. Does the PTC used in the power supply need to meet the IEC 60730-1? Peter: Only the parts specified above. Summary: It seems you wish to use a cheap enclosure material (94HB). Get a fused applied inlet. Install a fuse value based on the transformer pri/sec turns ratio as mentioned above. Use a transformer with a 94V-1 fire enclosure over the windings and make sure its' wires are PVC, TFE, PTFE, FEP or neoprene. With the fuse bypassed, make sure you meet the limit for Isc (A) and S (VA) in Table 9 in the standard. You are all set and ready. 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 -Original Message- From: Alex McNeil [mailto:alex.mcn...@ingenicofortronic.com] Sent: Friday, August 30, 2002 11:25 AM To: 'emc-p...@majordomo.ieee.org' Subject: EN60950-1 Sect 2.5 Limited Power sources Hi group, I have a query on the understanding of the above section. I thought I fully understood it until I used a different lab for Product Safety Compliance testing (both accredited!). We use a linear (basically a transformer with a PTC thermistor) class II SELV O/P stand alone power supply rated 10Vac, 5A. One of the labs tested the O/P Isc with a direct application of the sc. The other lab tested the O/P Isc by applying a load of 8A. The results were therefore interpreted differently. Isc (direct) = 30A falling to 0A within 30secs. Considered a PASS (8A for 1min) Isc (8A load) = 8A for 2mins. Considered a FAIL (8A 1min) This has a crucial bearing on whether I need a fire enclosure or not for my all plastic enclosure! 1. What is the correct method to test for a Limited Power source in determining what enclosure is required? 2. If a fire enclosure was needed what is the minimum plastic rating i.e. 94V0, V1 or what? 3. I cannot put a 5A fuse in the product, the lab says that the overcurrent protective device must be outwith the non-fire enclosure in order to stop the non compliant energy source entering the enclosure. Is this correct? 4. Similarly, I cannot use a resettable fuse in the product to meet these
2003 IEEE INTERNAIONAL SYMPOSIUM ON EMC - CALL FOR PAPERS
THE 2003 IEEE INTERNATIONAL SYMPOSIUM ON ELECTROMAGNETIC COMPATIBILITY (EMC) Istanbul Hilton Hotel, Istanbul, Turkey, May 11-16, 2003 Dear colleagues and fellow EMC engineers, Hello from Turkey, We take great pleasure in inviting you to participate in the 2003 IEEE International Symposium on EMC, which will be held with the cooperation of our colleagues in Turkey, at the Hilton Hotel in Istanbul, Turkey on May 1116, 2003. THIS IS A FRINEDLY REMINED THAT THE SUBMISSIONS FOR THE 2003 IEE INTERNATIONAL SYMPOSIUM ON EMC (ISTANBUL) ARE DUE 6 WEEKS FROM TODAY (OCTOBER 13) PLEASE ENCOURAGE YOUR FRIENDS AND PROFESSIONAL ASSOCIATES TO SUBMIT TECHNICAL PAPERS FOR THE SYMPOSIUM. THIS WILL BE A SYMPOSIUM RADIATING COMPATIBILITY FROM THE EAST... The symposium will provide a platform for the presentation and discussion of new developments in the field of electromagnetic compatibility and related topics. Paper sessions will include topics on the Electromagnetic Environmental Effects, EMC Education and Management, EMC Design, from Circuit to System, Spectrum Engineering, High Power Microwave Effects and Electromagnetic Threats, Signal Integrity and High Speed Considerations, Product Safety, Radiation Hazards and Biological Effects of EMF, and many, many other exciting topics. Workshops, tutorials, Birds of a Feather panels and special invited sessions will be organized on stimulating topics. The scientific committee is inviting you to contribute to the following specific technical activities, which currently in the process of being formulated: NO. SYMPOSIUM EVENT CONTRIBUTION CHAIRMAN ADDRESS FOR CONTACTS 1 Workshop on EMC Problems and Solutions for Short-range Communication under License- free Regulations (Note 1) Presentation Alan Bensky aben...@barak-online.net mailto:aben...@barak-online.net 2 Educational EMC Session Papers Prof.Heyno Garbe ga...@geml.uni-hannover.de mailto:ga...@geml.uni-hannover.de 3 Signal Integrity Session Papers Mark Montrose mmont...@ix.netcom.com mailto:mmont...@ix.netcom.com 4 War Stories Session Presentations Alex Axelrod alex_axel...@yahoo.com mailto:alex_axel...@yahoo.com 5 EMC Experiments EMC Experiments Dr.Andy Drozd and...@aol.com mailto:and...@aol.com 6 EMC Computer Simulations Demonstrations Dr.Andy Drozd and...@aol.com 7. Intentional EMI Papers Dr. Bill Radasky wrada...@aol.com PAPER SUBMISSION Prospective authors are invited to submit- by October 13, 2002, an abstract and preliminary manuscripts in English electronically- via using our on line submission system. For detailed instructions on file submission please visit the Symposiums official web site at http://www.ortra.com/emc2003/ and go to the Call for Papers page. TECHNICAL EXHIBITION The Symposium will be accompanied by a technical exhibition on EMC. Prospective exhibitors are invited to order a booking kit from the mailto:emc2...@ortra.co.il Symposium Secretariat for exhibition space, constructed stands, showcases, mural display areas and advertisement space in conference publications. We expect exciting new product launches and exhibitor events during the Symposium. Do not miss this unique opportunity! FOR ADDITIONAL INFORMATION or questions, PLEASE CONTACT THE SYMPOSIUM SECRETARIAT: ORTRA Ltd. 1 Nirim Street, P.O. Box 9352 61092 Tel-Aviv, Israel Tel: +972-3-638 Fax: +972-3-6384455 mailto:i...@ortra.co.il E-mail: emc2...@ortra.co.il OR VISIT OUR WEB SITE AT: Web site: http://www.ortra.com/ http://www.ortra.com/emc2003BM__Hlt516822820 Looking forward to welcoming you in Istanbul, Best Regards Elya B. Joffe Symposium Chairman --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
Ampacity
Safety Folks - I have a question for the group on the effects of temperature rating and deterioration. If a pcb is rated X degrees C, and the sizing of the power traces on an inner layer is such that the pcb temperature is now (X-1) degrees C, What effect does this have on the longevity of the pcb? At what %of the temperature board rating X will discoloration occur? I would appreciate all comments, so please fee free to respond to the group or to me directly. Thanks. Regards, Mark F. Gill, PE Sr. Engineer C-MAC Design Corporation, A Solectron Company 4222 Emperor Blvd, Suite 300 RTP, NC 27703 P: (919)-474-3569 markg...@solectron.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
Re: JIS C 6861
On Tue, 27 Aug 2002 10:55:57 -0400, richwo...@tycoint.com wrote: Is JIS C 6861, mechanical standard for plastic fiber optic cable, the same as IEC 6079-2? JIS C 6861 says that it was written with the intention to make it harmonized with the requirements of IEC 60794-1. I'm not sure if those requirements are exactly identical or not. Regards, Tom -- Tomonori Sato vef00...@nifty.ne.jp URL: http://member.nifty.ne.jp/tsato/ --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
Re: Electric Fence Controllers
I read in !emc-pstc that John Allen ja014d7...@blueyonder.co.uk wrote (in 048001c24f9d$bd8895a0$0200a8c0@johnallen) about 'Electric Fence Controllers' on Thu, 29 Aug 2002: I once (about 12 years ago) had the dubious priviledge of being the Comittee Secretary for the UK BSI standards committee dealing with these beasts at British International levels! What is now CPL/61? This question was never asked (that was probably before my time!) but it was my impression that these had fallen into the too difficult category and the Commission at the time of the Directive (1972/73)ducked the issue to ensure that it got agreed and that all the more common items got dealt with.. I think you are right. There certainly was (and probably still is - which is why the situation in the Directive does not appear to have changed) Item 10 of the Commission 'request for comment document 'LVD Update 1' says: QUOTE General support to include Electric fence controller to the scope of the LVD. France: Objection because the intended use of these products is not inline with the aims of the directive. ENDQUOTE a considerable difference of opinion between various countries as their safety and what the voltage and particular pulse tim/energy limits should apply. Indeed. Related to the perimeters of typical fields. Effectively, countries with small fields (like many in Europe) wanted low power units which probably were safe enough for general use, and possibly could have been kept within the LVD by some form of energy limitation kluge. However, countries with big - or very big (like Australia and New Zealand, etc.) - fields wanted units with lots more energy to avoid the deterent effect being substantially reduced by contact with conductive vegetation, etc. Of course, at agricultural shows in Britain, they are demonstrated producing 5 cm sparks. I wonder how they do that. (;-) In the end (after I left BSI) I believe that some units were finally covered under Part 2 Sections of IEC 60335 - but I personally doubt that they are the high power versions. BS EN 60335-2-76. -- 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...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
I wonder about some comments in IEC 664-1:1992
Dear members I don't have a standard (IEC 664-1:1992). But, I wonder about some comments in IEC 664-1:1992 as below; 1. What does mean R.I.V. (Rated Insulation Voltage)? Is it working voltage or EUT's rated voltage? If it is not... hm please explain for me. ^_^; 2. Are Table 2's distances Basic requirement? I don't have a standard, but anyone tells as talk. 3. If I will conduct IMPULSE TEST... Must I apply between where and where? (EUT has a Linear Transformer, SMPSs and communication boards) I don't know so many things in standards. Please give your help. Michael Jang --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
EN60950-1 Sect 2.5 Limited Power sources
Hi group, I have a query on the understanding of the above section. I thought I fully understood it until I used a different lab for Product Safety Compliance testing (both accredited!). We use a linear (basically a transformer with a PTC thermistor) class II SELV O/P stand alone power supply rated 10Vac, 5A. One of the labs tested the O/P Isc with a direct application of the sc. The other lab tested the O/P Isc by applying a load of 8A. The results were therefore interpreted differently. Isc (direct) = 30A falling to 0A within 30secs. Considered a PASS (8A for 1min) Isc (8A load) = 8A for 2mins. Considered a FAIL (8A 1min) This has a crucial bearing on whether I need a fire enclosure or not for my all plastic enclosure! 1. What is the correct method to test for a Limited Power source in determining what enclosure is required? 2. If a fire enclosure was needed what is the minimum plastic rating i.e. 94V0, V1 or what? 3. I cannot put a 5A fuse in the product, the lab says that the overcurrent protective device must be outwith the non-fire enclosure in order to stop the non compliant energy source entering the enclosure. Is this correct? 4. Similarly, I cannot use a resettable fuse in the product to meet these requirements? 5. Does the PTC used in the power supply need to meet the IEC 60730-1? I would very much appreciate clarification on this matter. THANKS!! Kind Regards Alex McNeil Principal Engineer Tel: +44 (0)131 479 8375 Fax: +44 (0)131 479 8321 email: alex.mcn...@ingenicofortronic.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: Electric Fence Controllers
Stuart, I would assume that the power supply providing power to the fence is the normal utility supply (115/230 V). Therefore, the system is indeed covered by the LVD. 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 -Original Message- From: Ablewisp - Compliance Consultants [mailto:s...@ablewisp.com] Sent: Thursday, August 29, 2002 5:11 PM To: Emc-Pstc Subject: Electric Fence Controllers Hi I've been asked why electric fence controllers are outside the scope of the LVD. I don't know much about them and assume its because they generate voltages exceeding the LVD upper limit. Is my assumption correct? Many thanks Stuart Miller --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: Abnormal test and SELV / 60950
Pierre, The compliance criteria for abnormal operating and fault conditions are specified in 5.3.8.1 (during the tests) and 5.3.8.2 (after the tests). These specs do not require you to measure SELV voltages during or after abnormals and this is why in many test reports you do not see the SELV limits under this clause. However, look at 2.2.3 Voltages under Fault Conditions. This spec requires you to measure the SELV voltages under fault conditions. Therefore, to answer you question, yes, you dio need to measure the voltages uner single fault conditions and make sure it complies with 2.2.3. Best Regards, 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 -Original Message- From: Pierre SELVA [mailto:e.l...@wanadoo.fr] Sent: Thursday, August 29, 2002 11:08 PM To: Forum Safety-emc Subject: Abnormal test and SELV / 60950 Hi all, When abnormal tests are performed against clause 5.3 of IEC 60950 3rd ed, do we have to measured the SELV voltage to be sure they are in the limits as defined in case of first default. I never seen reports where it's done, but I've performed tests where these voltage were outside the SELV values. What is your opinion on this matter ? Thanks a lot for your answers, Pierre Selva eLABs (emc, safety, radio, eco-design - product regulations) 1 rue des Essarts 38610 GIERES - FRANCE 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...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
Re: Electric Fence Controllers
Ah yes, -sparking, sizzling wire fences... About 40 yrs ago I spent a few summers visiting with an uncle and family on his Iowa farm. He had a small electrified pen with hogs in it. My cousin would dare me to take a blade of grass and loop it around the wire to see how much jolt I could take before letting go. The loop usually burnt through before I reached threshold, unless I ignorantly used a wide blade of buffalo grass... One heavily dewed morning, we were heading for the car to go to town and another cousin, Kerry Sue (who lived on the farm), excitedly ran toward the car (to occupy the shotgun position) that was parked adjacent to the hog pen. She slipped on the wet weeds. Her body slid under the electrified wires, wrapping her long hair around the lowest conductor. We stood around and laughed as she yelled and convulsed from the pulses. You could actually see tiny arcs in her hair. -maybe that's why to this day she is so docile... Most of these chargers are rated by the miles of wire they can energize, up to 20 miles worth! I seem to remember versions that were battery powered and only a few that were line powered. Determining safety requirements for these is why we get the big bucks...grin Happy Labor Day Holiday (USA), Kyle - Original Message - From: Pettit, Ghery ghery.pet...@intel.com To: 'John Allen' ja014d7...@blueyonder.co.uk; Ablewisp - Compliance Consultants s...@ablewisp.com; Emc-Pstc emc-p...@majordomo.ieee.org Sent: Thursday, August 29, 2002 4:01 PM Subject: RE: Electric Fence Controllers Reminds me of when my son (now 25) was very young. We were visiting relatives in California who used electric fences to keep the cattle where they belonged. We were sitting around talking when my son came into the house with eyes as big as saucers to report that the fence shook me!. It took a moment for us to realize what had happened, and then the poor kid had to listen to us all crack up. He grabbed the wire between pulses, then got the treatment. He's been very careful around electric fences ever since. And these fencers were used on multiple thousand foot runs of wire. You could find the shorts to vegetation by walking the fence and listening for the arc. Ghery Pettit -Original Message- From: John Allen [mailto:ja014d7...@blueyonder.co.uk] Sent: Thursday, August 29, 2002 1:51 PM To: Ablewisp - Compliance Consultants; Emc-Pstc Subject: Re: Electric Fence Controllers Hi Folks I once (about 12 years ago) had the dubious priviledge of being the Comittee Secretary for the UK BSI standards committee dealing with these beasts at British International levels! This question was never asked (that was probably before my time!) but it was my impression that these had fallen into the too difficult category and the Commission at the time of the Directive (1972/73)ducked the issue to ensure that it got agreed and that all the more common items got dealt with.. There certainly was (and probably still is - which is why the situation in the Directive does not appear to have changed) a considerable difference of opinion between various countries as their safety and what the voltage and particular pulse tim/energy limits should apply. Effectively, countries with small fields (like many in Europe) wanted low power units which probably were safe enough for general use, and possibly could have been kept within the LVD by some form of energy limitation kluge. However, countries with big - or very big (like Australia and New Zealand, etc.) - fields wanted units with lots more energy to avoid the deterent effect being substantially reduced by contact with conductive vegetation, etc. In the end (after I left BSI) I believe that some units were finally covered under Part 2 Sections of IEC 60335 - but I personally doubt that they are the high power versions. Does'nt really explain the situation fully but might give you some idea of what was/is behind the exclusion - and do'nt forget that there are other exclusions as well. Regards John Allen - Original Message - From: Ablewisp - Compliance Consultants s...@ablewisp.com To: Emc-Pstc emc-p...@majordomo.ieee.org Sent: Thursday, August 29, 2002 4:11 PM Subject: Electric Fence Controllers Hi I've been asked why electric fence controllers are outside the scope of the LVD. I don't know much about them and assume its because they generate voltages exceeding the LVD upper limit. Is my assumption correct? Many thanks Stuart Miller --- 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:
RE: requirements for ITE power cords
Sorry to knock your substantially built comment, but the derating is not based on the plug. In fact the 15 and 20 amp plugs are the same construction with different configuration. Both can be used at full rating. The circuit they are used in contains the limitation. The derating on North American circuits is based on thermal considerations. The derating (80% of rated load) applies to all continuous loads which are defined as over 3 hours. ITE is considered continuous by default. The long term degradation of wire insulation is related to temperature and time. Given considerations such as neighboring conductors, thermal insulation, current, duration, wire gauge, etc, this is one way the code allows for higher short term loads. Bob Johnson ITE Safety -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org] On Behalf Of John Allen Sent: Thursday, August 29, 2002 5:28 PM To: richwo...@tycoint.com; emc-p...@majordomo.ieee.org Subject: Re: requirements for ITE power cords Hi Folks Sorry to be late in replying on this one - and not really trying to disagree - but I think you will find that the 125% rule is a North American convention and also followed by countries which use similar installation practice (i.e. that have plugs with quite small blades/pins!). The same rule does not - to the best of my knowledge - apply in Europe ( certainly not in the UK) and other countries that follow European installation practice where derating is not required as our plugs are more substantially built! Therefore we can use a 13 (UK) or 16A (Europe) cable and 13A or 16A plug on an equipment rated at 13A/16A respectively, e.g: re it applies in respect of the EN60950 standard. Regards John Allen - Original Message - From: richwo...@tycoint.com To: emc-p...@majordomo.ieee.org Sent: Thursday, August 15, 2002 11:59 AM Subject: RE: requirements for ITE power cords George, the ITE safety standards require that the plug be rated for at least 125% of the equipment rating. I believe that the US National Electrical Code has the same requirement. Richard Woods Sensormatic Electronics Tyco International -Original Message- From: George Stults [mailto:george.stu...@watchguard.com] Sent: Wednesday, August 14, 2002 6:28 PM To: 'emc-p...@majordomo.ieee.org' Subject: requirements for ITE power cords Hello Group, Recently my purchasing department asked me to recommend standards for power cords. These are detachable power cords for ITE equipment, both 3-wire and 2-wire. Typically the cords are marked with one or more of CSA, UL, (Dentori T). The ones we get are typically rated from 6 to 10 times the required current for a given product. My question is, are there required or recommended power cord design margins for current, voltage, power, temperature range, insulation, etc. spelled out in IEC/EN 60950 or UL1950 or MIL-HDBK 217 or elsewhere? Thanks in advance George Stults --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- 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
Re: PCB design guideline
Peter, There is a summary for PCB design rules relating to EMC , (131351 bytes). It deals with the developments, rules and guidelines leading to my thesis, http://www.geocities.com/timfoo6143/Design_Rules.pdf A link could be found in the main page which leads to the rest of the thesis. http://www.geocities.com/timfoo6143/ sincerely, Tim Foo peterh...@aol.com Sent by: To: emc-p...@majordomo.ieee.org owner-emc-pstc@majordo cc: (bcc: Wan Juang Foo/ece/staff/npnet) mo.ieee.orgSubject: PCB design guideline 08/30/02 03:50 AM Please respond to Peterhays Hello Group, Has anyone got a brief document that outlines how to design PCB to have a better EMC/EMI performance? I basically need to give some basic guideline to our PCB guy . I know some of it myself. Things such as separation of high frequency from low frequency, good ground plane, etc. Any help is appreciated. thanks Peter snip --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
Re: Transmission line formula?
I read in !emc-pstc that Cortland Richmond 72146@compuserve.com wrote (in 200208291324_mc3-1-dc8-8...@compuserve.com) about 'Transmission line formula?' on Thu, 29 Aug 2002: Put two 3-foot pieces of your material at some convenient spacing. Using a Z meter, find the quarter-wavelength frequency, where the impedance will be zero (open stub), around 82 MHz. When you've found THAT, measure the impedance at HALF this frequency. The reactive impedance of a one-eighth wave stub is equal to its characteristic impedance. Adjust spacing for desired impedance. That's a very useful technique! You can find the characteristic impedance of a cable that way. And you can use, for example, a signal generator and spectrum analyser to find the zero-impedance frequency, or a signal or sweep generator and diode probe. -- 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...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
Re: Insulation Distance Between Circuitboard Layers (Safety)
I read in !emc-pstc that Doug McKean dmck...@corp.auspex.com wrote (in 004b01c24f87$66393680$cb3e3...@corp.auspex.com) about 'Insulation Distance Between Circuitboard Layers (Safety)' on Thu, 29 Aug 2002: FR4 has a dielectric factor of about 4.7. That simply means it's 4.7 times stronger than air. Therefore, *in theory* 1KV should in theory break down (1/4.7) mm of FR4, or 0.21 mm of FR4. One would need to distinguish VERY carefully between 'dielectric factor' as you have defined it and 'dielectric constant', which is also about 5 for FR4, I believe, but means something quite different. -- 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...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
