RE: IEC 61000-4-2 ESD 61000-4-5 Surge lower levels
David, I would add my voice to the notes below. In particular it was for keyboards, and we tested at discrete steps. 2, 4, 6, 8, and then jumped in 4K increments to 12, and 16 - occasionally to 20K for a specific customer requirement. HP for example. We too noted failures at lower levels that did not repeat at higher levels. Principally in the 2 to 8K range, because at the higher levels we changed the acceptance level from not sending out false codes to just not locking up the processor. These were principally in the air discharge mode - but repeatable within the 20 discharges at each test point. By the way I enjoyed the article you sent me on the arc length testing - it at least gives me insight on why the method is presumed to simulate how an actual human/metal ESD event occurs - through air. The data was presented for 5 Kv, but I couldn't tell whether it could also be used for different levels. Sorry, I know from an empirical standpoint you need the data in your hands not just recollection of events, but those tests were done for a different company - but enough voices saying the same thing provide a strong argument for confirming or denying the presumption scientifically. That sounds like its right up your professorial ally and lord knows you have to have some unwitting undergrads you could trick into the process. Certainly would be ideal if it did, or that some adjustment mechanism could be applied to a simulator for each voltage. That would allow for much more automated testing. Gary -Original Message- From: Scott Douglas [mailto:dougl...@naradnetworks.com] Sent: Wednesday, June 12, 2002 5:01 AM To: Pommerenke, David Cc: EMC-PSTC Subject: RE: IEC 61000-4-2 ESD 61000-4-5 Surge lower levels David, Have been (still am) out of the office testing this week. I am sorry to say that I cannot provide hard data to support my comments. That experience was two lifetimes ago at a different employer. It happened on more than one product model and on more than one of each model. I do know that we would make 50 discharges at each test point. And, there were more than ten test points on each model. Not every test point would exhibit the problem, but those that did were consistent, something like 60% of discharges would cause the system display to scramble. The peak failure voltage was around 1.8 kV, with only a very few failures at 4 kV and none at 8 or 15 kV. All were in contact mode. This was all engineering work prior to official test house testing. We identified the problems and made changes and re-tested. Once we got all tests to pass, we would go for the official test. We had several of these type of problems. Once was the scrambled (actually went black) LCD display. Solved by shielding the cable to the display and termination resistors on the display PCB. Another time was black lines in the recorded output (film recorder products). This was corrected by proper grounding of the I/O connector shell. Third time was system hang-up. If I recall this one correctly, we added decoupling caps to chassis ground at the I/O connector on the mother board. In all cases, the problems were at mid level tests, usually 2 or 4 kV, rarely at 8 kV, and never at 15 kV. Scott At 08:33 PM 6/10/02 -0500, you wrote: Dear Scott, (1) I have looked at quite a bit of literature that plots Failure propatibility vs. Stress level in contact mode like testing and have seen very few none-monotonic EUTs that show the none-monotonic behavior over a larger voltage range. (2) In my five year test practise at HP, I have only seen one EUT that failed at lower levels and passed at higher levels in contact mode. If you have data that showsAs others have said, I have seen numerous failures at less than the maximum required test voltage while the same system passes at the max required voltage. please share that data with me if it is in contact mode and if the number of discharges at each level is large enough to obtain an acceptable confidence level. Regards David Pommerenke --- 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
RE: IEC 61000-4-2 ESD 61000-4-5 Surge lower levels
Dear Group, The physics of air discharge (= the reason for the variatins, the effect of humidity, speed of approach) is quite well explained in D. Pommerenke, 'ESD: Transient Fields, Arc Simulation and Rise Time Limit' , Journal of Electrostatics 1995 36 (1995), pp. 31 - 54 David Pommerenke --- 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: IEC 61000-4-2 ESD 61000-4-5 Surge lower levels
Further to my earlier email. The ESD test that we were undertaking was on a digital device. The ESD was direct discharge and at the voltage level of failure, about 3 out or 10 discharges were failing. Since device operation was dependent upon the data being received, it was considered that the point in the data stream at which the discharge occured defined the effect on the product. Regards, Neil Helsby ** This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the system manager. This footnote also confirms that this email message has been swept by MIMEsweeper for the presence of computer viruses. www.mimesweeper.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: IEC 61000-4-2 ESD 61000-4-5 Surge lower levels
Hi - Quite a while ago, in the 80's I think W.M King published some papers that demonstrated the differences in the ESD waveforms in rise times as the voltage increased. So an ESD pulse of 2kV would occupy a wider spectral bandwidth than a 15kV pulse. Whats important to realize, is that he performed the measurements by charging the ESD gun and approaching the target. So the series impedance of the discharge at the higher voltages (much less at the lower voltages) tended to slow the rise time. David, I would postulate that the reason you haven't seen this effect is because of the new approach to ESD testing: that is for direct discharges the ESDgun is intimately contact to the product BEFORE apply the discharge. This was done to minimize test variabilities. Chas From: Pommerenke, David davi...@ece.umr.edu Reply-To: Pommerenke, David davi...@ece.umr.edu To: Scott Douglas dougl...@naradnetworks.com, emc-p...@majordomo.ieee.org Subject: RE: IEC 61000-4-2 ESD 61000-4-5 Surge lower levels Date: Mon, 10 Jun 2002 20:33:57 -0500 Dear Scott, (1) I have looked at quite a bit of literature that plots Failure propatibility vs. Stress level in contact mode like testing and have seen very few none-monotonic EUTs that show the none-monotonic behavior over a larger voltage range. (2) In my five year test practise at HP, I have only seen one EUT that failed at lower levels and passed at higher levels in contact mode. If you have data that showsAs others have said, I have seen numerous failures at less than the maximum required test voltage while the same system passes at the max required voltage. please share that data with me if it is in contact mode and if the number of discharges at each level is large enough to obtain an acceptable confidence level. Regards David Pommerenke [Pommerenke, David] -Original Message- From: Scott Douglas [mailto:dougl...@naradnetworks.com] Sent: Monday, June 10, 2002 4:46 PM To: emc-p...@majordomo.ieee.org Subject: RE: IEC 61000-4-2 ESD 61000-4-5 Surge lower levels David, I disagree with you here. As others have said, I have seen numerous failures at less than the maximum required test voltage while the same system passes at the max required voltage. It seems to me the intent was / is / should be to verify product performance up to a maximum level, not just at that level. The logic here would be that the standards writing group would make the test cover reasonable ground up to some limit because it is quite common that anything up to that limit could happen. The reason for the limit is because it is uncommon for things larger / higher than the limit to happen. Contact discharge is the only way to make reliable and repeatable tests for ESD. No approach speed issues, etc. So testing at low levels and working up to a maximum limit is a reasonable test method. On the other hand, I find air discharge to be a difficult and not very repeatable test to do which causes me to question its usefulness. Yes, I agree that people interacting with products will more often see air discharge rather than contact discharge. But I also find it impossible to reliably repeat air discharge test results. The old approach speed, distance and coordinates of contact point issue. Until someone can make an automated air discharge tester that keeps human interactions out of the process, I can't see it being corrected. That said, testing at lower levels is just as necessary here. Regards, Scott Douglas Senior Compliance Engineer Narad Networks 515 Groton Road Westford, MA 01886 office: 978 589-1869 cell: 978-239-0693 dougl...@naradnetworks.com www.naradnetworks.com http://www.naradnetworks.com/ At 08:36 AM 6/10/02 -0500, Pommerenke, David wrote: Dear Group, For most EUTs there is no need to do lower level testing in contact mode ESD. The time is better spend (meaning a better test results uncertainty is achieved) if the number of discharges is increased at the highest test level (hundreds is a good number). Although it is possible that a system fails at e.g., 2 kV contact mode (e.g., incomplete reset) and passes at 4 kV contact mode (full self-recovering quick reset) the likelyhood of that happening is not that large to require it in a standard. For air discharge lower level testing is needed, as the risetime is often much lower at lower voltages. Of course, if no discharge occurs, no further testing at even lower levels makes sense. I do know that what I am saying violates the present IEC 61000-4-2 standard. ut it reflects the coming version of IEC 61000-4-2. The standard does not intend to protect agains every possible ESD failure. I would like to receive your input, as I am one of the US-representatives in IEC TC77b WG-9 (ESD). David Pommerenke _ MSN Photos is the easiest way to share and print your photos: http://photos.msn.com
RE: IEC 61000-4-2 ESD 61000-4-5 Surge lower levels
Dear Scott, (1) I have looked at quite a bit of literature that plots Failure propatibility vs. Stress level in contact mode like testing and have seen very few none-monotonic EUTs that show the none-monotonic behavior over a larger voltage range. (2) In my five year test practise at HP, I have only seen one EUT that failed at lower levels and passed at higher levels in contact mode. If you have data that showsAs others have said, I have seen numerous failures at less than the maximum required test voltage while the same system passes at the max required voltage. please share that data with me if it is in contact mode and if the number of discharges at each level is large enough to obtain an acceptable confidence level. Regards David Pommerenke [Pommerenke, David] -Original Message- From: Scott Douglas [mailto:dougl...@naradnetworks.com] Sent: Monday, June 10, 2002 4:46 PM To: emc-p...@majordomo.ieee.org Subject: RE: IEC 61000-4-2 ESD 61000-4-5 Surge lower levels David, I disagree with you here. As others have said, I have seen numerous failures at less than the maximum required test voltage while the same system passes at the max required voltage. It seems to me the intent was / is / should be to verify product performance up to a maximum level, not just at that level. The logic here would be that the standards writing group would make the test cover reasonable ground up to some limit because it is quite common that anything up to that limit could happen. The reason for the limit is because it is uncommon for things larger / higher than the limit to happen. Contact discharge is the only way to make reliable and repeatable tests for ESD. No approach speed issues, etc. So testing at low levels and working up to a maximum limit is a reasonable test method. On the other hand, I find air discharge to be a difficult and not very repeatable test to do which causes me to question its usefulness. Yes, I agree that people interacting with products will more often see air discharge rather than contact discharge. But I also find it impossible to reliably repeat air discharge test results. The old approach speed, distance and coordinates of contact point issue. Until someone can make an automated air discharge tester that keeps human interactions out of the process, I can't see it being corrected. That said, testing at lower levels is just as necessary here. Regards, Scott Douglas Senior Compliance Engineer Narad Networks 515 Groton Road Westford, MA 01886 office: 978 589-1869 cell: 978-239-0693 dougl...@naradnetworks.com www.naradnetworks.com http://www.naradnetworks.com/ At 08:36 AM 6/10/02 -0500, Pommerenke, David wrote: Dear Group, For most EUTs there is no need to do lower level testing in contact mode ESD. The time is better spend (meaning a better test results uncertainty is achieved) if the number of discharges is increased at the highest test level (hundreds is a good number). Although it is possible that a system fails at e.g., 2 kV contact mode (e.g., incomplete reset) and passes at 4 kV contact mode (full self-recovering quick reset) the likelyhood of that happening is not that large to require it in a standard. For air discharge lower level testing is needed, as the risetime is often much lower at lower voltages. Of course, if no discharge occurs, no further testing at even lower levels makes sense. I do know that what I am saying violates the present IEC 61000-4-2 standard. ut it reflects the coming version of IEC 61000-4-2. The standard does not intend to protect agains every possible ESD failure. I would like to receive your input, as I am one of the US-representatives in IEC TC77b WG-9 (ESD). David Pommerenke
Re: IEC 61000-4-2 ESD 61000-4-5 Surge lower levels
Not to mention the vastly different current risetimes. Low voltage discharges actually have higher di/dt values than high voltage ones (and therefore higher interference potential). Doug don_borow...@selinc.com wrote: Let me add a bit on the air discharge side. You will want to do the lower voltage discharge tests because the path the discharge takes may change with voltage. I have seen several instances where connectors (sub-min D types, if I remember correctly) were mounted on metal panels. At higher voltages, the path between the ESD gun and the grounded shell of the connector would break down first. At lower voltages, the connector pins could be approached without breakdown to the shell, and the discharge would occur to the connector pins. Don Borowski Schweitzer Engineering Labs Pullman, WA Pommerenke, David davi...@ece.umr.edu on 06/10/2002 06:36:46 AM Please respond to Pommerenke, David davi...@ece.umr.edu To: Neil Helsby nei...@solid-state-logic.com, emc-p...@majordomo.ieee.org cc: kro...@yahoo.com (bcc: Don Borowski/SEL) Subject: RE: IEC 61000-4-2 ESD 61000-4-5 Surge lower levels Dear Group, For most EUTs there is no need to do lower level testing in contact mode ESD. The time is better spend (meaning a better test results uncertainty is achieved) if the number of discharges is increased at the highest test level (hundreds is a good number). Although it is possible that a system fails at e.g., 2 kV contact mode (e.g., incomplete reset) and passes at 4 kV contact mode (full self-recovering quick reset) the likelyhood of that happening is not that large to require it in a standard. For air discharge lower level testing is needed, as the risetime is often much lower at lower voltages. Of course, if no discharge occurs, no further testing at even lower levels makes sense. I do know that what I am saying violates the present IEC 61000-4-2 standard. ut it reflects the coming version of IEC 61000-4-2. The standard does not intend to protect agains every possible ESD failure. I would like to receive your input, as I am one of the US-representatives in IEC TC77b WG-9 (ESD). David Pommerenke -Original Message- From: Neil Helsby [mailto:nei...@solid-state-logic.com] Sent: Monday, June 10, 2002 4:56 AM To: emc-p...@majordomo.ieee.org Cc: kro...@yahoo.com Subject: Re: IEC 61000-4-2 ESD 61000-4-5 Surge lower levels I think there are two points here. 1) If you believe that in the environment in which it will be used, your product may be subject to levels in excess of that defined in the standard, you must test to that higher level. 2) Yes, failures can occur at mid range levels. We have just recently experienced this problem with ESD. Below about 3.5 kV and above about 4.5 kV the product worked fine. But at 4 kV we experienced a failure mode. If we had only tested at 8 kV we would have missed the problem. I also had a problem some years ago with mains voltage dips to 0V. Having a test set that enabled the period to be varied in ms increments, I discovered a problem affecting a voltage regulator. When the mains dip was between about 16 ms and 35 ms, the regulator went into a bistable mode switching on then off at each pulse. Outside these periods, it worked satisfactorily, eventually losing output when the period was extended. The problem with investigating these types of failure is determining the size of step between measurements. Too short a step and you will be testing forever, too long and you could miss a narrow band of problem. Regards, Neil Helsby ** This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the system manager. This footnote also confirms that this email message has been swept by MIMEsweeper for the presence of computer viruses. www.mimesweeper.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: IEC 61000-4-2 ESD 61000-4-5 Surge lower levels
David, I disagree with you here. As others have said, I have seen numerous failures at less than the maximum required test voltage while the same system passes at the max required voltage. It seems to me the intent was / is / should be to verify product performance up to a maximum level, not just at that level. The logic here would be that the standards writing group would make the test cover reasonable ground up to some limit because it is quite common that anything up to that limit could happen. The reason for the limit is because it is uncommon for things larger / higher than the limit to happen. Contact discharge is the only way to make reliable and repeatable tests for ESD. No approach speed issues, etc. So testing at low levels and working up to a maximum limit is a reasonable test method. On the other hand, I find air discharge to be a difficult and not very repeatable test to do which causes me to question its usefulness. Yes, I agree that people interacting with products will more often see air discharge rather than contact discharge. But I also find it impossible to reliably repeat air discharge test results. The old approach speed, distance and coordinates of contact point issue. Until someone can make an automated air discharge tester that keeps human interactions out of the process, I can't see it being corrected. That said, testing at lower levels is just as necessary here. Regards, Scott Douglas Senior Compliance Engineer Narad Networks 515 Groton Road Westford, MA 01886 office: 978 589-1869 cell: 978-239-0693 dougl...@naradnetworks.com www.naradnetworks.com At 08:36 AM 6/10/02 -0500, Pommerenke, David wrote: Dear Group, For most EUTs there is no need to do lower level testing in contact mode ESD. The time is better spend (meaning a better test results uncertainty is achieved) if the number of discharges is increased at the highest test level (hundreds is a good number). Although it is possible that a system fails at e.g., 2 kV contact mode (e.g., incomplete reset) and passes at 4 kV contact mode (full self-recovering quick reset) the likelyhood of that happening is not that large to require it in a standard. For air discharge lower level testing is needed, as the risetime is often much lower at lower voltages. Of course, if no discharge occurs, no further testing at even lower levels makes sense. I do know that what I am saying violates the present IEC 61000-4-2 standard. ut it reflects the coming version of IEC 61000-4-2. The standard does not intend to protect agains every possible ESD failure. I would like to receive your input, as I am one of the US-representatives in IEC TC77b WG-9 (ESD). David Pommerenke
RE: IEC 61000-4-2 ESD 61000-4-5 Surge lower levels
Let me add a bit on the air discharge side. You will want to do the lower voltage discharge tests because the path the discharge takes may change with voltage. I have seen several instances where connectors (sub-min D types, if I remember correctly) were mounted on metal panels. At higher voltages, the path between the ESD gun and the grounded shell of the connector would break down first. At lower voltages, the connector pins could be approached without breakdown to the shell, and the discharge would occur to the connector pins. Don Borowski Schweitzer Engineering Labs Pullman, WA Pommerenke, David davi...@ece.umr.edu on 06/10/2002 06:36:46 AM Please respond to Pommerenke, David davi...@ece.umr.edu To: Neil Helsby nei...@solid-state-logic.com, emc-p...@majordomo.ieee.org cc: kro...@yahoo.com (bcc: Don Borowski/SEL) Subject: RE: IEC 61000-4-2 ESD 61000-4-5 Surge lower levels Dear Group, For most EUTs there is no need to do lower level testing in contact mode ESD. The time is better spend (meaning a better test results uncertainty is achieved) if the number of discharges is increased at the highest test level (hundreds is a good number). Although it is possible that a system fails at e.g., 2 kV contact mode (e.g., incomplete reset) and passes at 4 kV contact mode (full self-recovering quick reset) the likelyhood of that happening is not that large to require it in a standard. For air discharge lower level testing is needed, as the risetime is often much lower at lower voltages. Of course, if no discharge occurs, no further testing at even lower levels makes sense. I do know that what I am saying violates the present IEC 61000-4-2 standard. ut it reflects the coming version of IEC 61000-4-2. The standard does not intend to protect agains every possible ESD failure. I would like to receive your input, as I am one of the US-representatives in IEC TC77b WG-9 (ESD). David Pommerenke -Original Message- From: Neil Helsby [mailto:nei...@solid-state-logic.com] Sent: Monday, June 10, 2002 4:56 AM To: emc-p...@majordomo.ieee.org Cc: kro...@yahoo.com Subject: Re: IEC 61000-4-2 ESD 61000-4-5 Surge lower levels I think there are two points here. 1) If you believe that in the environment in which it will be used, your product may be subject to levels in excess of that defined in the standard, you must test to that higher level. 2) Yes, failures can occur at mid range levels. We have just recently experienced this problem with ESD. Below about 3.5 kV and above about 4.5 kV the product worked fine. But at 4 kV we experienced a failure mode. If we had only tested at 8 kV we would have missed the problem. I also had a problem some years ago with mains voltage dips to 0V. Having a test set that enabled the period to be varied in ms increments, I discovered a problem affecting a voltage regulator. When the mains dip was between about 16 ms and 35 ms, the regulator went into a bistable mode switching on then off at each pulse. Outside these periods, it worked satisfactorily, eventually losing output when the period was extended. The problem with investigating these types of failure is determining the size of step between measurements. Too short a step and you will be testing forever, too long and you could miss a narrow band of problem. Regards, Neil Helsby ** This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the system manager. This footnote also confirms that this email message has been swept by MIMEsweeper for the presence of computer viruses. www.mimesweeper.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
RE: IEC 61000-4-2 ESD 61000-4-5 Surge lower levels
Dear Group, For most EUTs there is no need to do lower level testing in contact mode ESD. The time is better spend (meaning a better test results uncertainty is achieved) if the number of discharges is increased at the highest test level (hundreds is a good number). Although it is possible that a system fails at e.g., 2 kV contact mode (e.g., incomplete reset) and passes at 4 kV contact mode (full self-recovering quick reset) the likelyhood of that happening is not that large to require it in a standard. For air discharge lower level testing is needed, as the risetime is often much lower at lower voltages. Of course, if no discharge occurs, no further testing at even lower levels makes sense. I do know that what I am saying violates the present IEC 61000-4-2 standard. ut it reflects the coming version of IEC 61000-4-2. The standard does not intend to protect agains every possible ESD failure. I would like to receive your input, as I am one of the US-representatives in IEC TC77b WG-9 (ESD). David Pommerenke -Original Message- From: Neil Helsby [mailto:nei...@solid-state-logic.com] Sent: Monday, June 10, 2002 4:56 AM To: emc-p...@majordomo.ieee.org Cc: kro...@yahoo.com Subject: Re: IEC 61000-4-2 ESD 61000-4-5 Surge lower levels I think there are two points here. 1) If you believe that in the environment in which it will be used, your product may be subject to levels in excess of that defined in the standard, you must test to that higher level. 2) Yes, failures can occur at mid range levels. We have just recently experienced this problem with ESD. Below about 3.5 kV and above about 4.5 kV the product worked fine. But at 4 kV we experienced a failure mode. If we had only tested at 8 kV we would have missed the problem. I also had a problem some years ago with mains voltage dips to 0V. Having a test set that enabled the period to be varied in ms increments, I discovered a problem affecting a voltage regulator. When the mains dip was between about 16 ms and 35 ms, the regulator went into a bistable mode switching on then off at each pulse. Outside these periods, it worked satisfactorily, eventually losing output when the period was extended. The problem with investigating these types of failure is determining the size of step between measurements. Too short a step and you will be testing forever, too long and you could miss a narrow band of problem. Regards, Neil Helsby ** This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the system manager. This footnote also confirms that this email message has been swept by MIMEsweeper for the presence of computer viruses. www.mimesweeper.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: IEC 61000-4-2 ESD 61000-4-5 Surge lower levels
I think there are two points here. 1) If you believe that in the environment in which it will be used, your product may be subject to levels in excess of that defined in the standard, you must test to that higher level. 2) Yes, failures can occur at mid range levels. We have just recently experienced this problem with ESD. Below about 3.5 kV and above about 4.5 kV the product worked fine. But at 4 kV we experienced a failure mode. If we had only tested at 8 kV we would have missed the problem. I also had a problem some years ago with mains voltage dips to 0V. Having a test set that enabled the period to be varied in ms increments, I discovered a problem affecting a voltage regulator. When the mains dip was between about 16 ms and 35 ms, the regulator went into a bistable mode switching on then off at each pulse. Outside these periods, it worked satisfactorily, eventually losing output when the period was extended. The problem with investigating these types of failure is determining the size of step between measurements. Too short a step and you will be testing forever, too long and you could miss a narrow band of problem. Regards, Neil Helsby ** This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the system manager. This footnote also confirms that this email message has been swept by MIMEsweeper for the presence of computer viruses. www.mimesweeper.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: IEC 61000-4-2 ESD 61000-4-5 Surge lower levels
The EMCTLA's Technical Guidance Note No 39 may be relevant here. These TGNs are guidance to UK test labs on how to apply the EMC directive and EMC test standards. You can get to TGN #39 via www.emctla.org. If it doesn't answer your question completely, send an email to the EMCTLA's secretary and he may be able to come up with a consensus decision for you. All the very best! Keith Armstrong www.cherryclough.com In a message dated 07/06/02 23:01:43 GMT Daylight Time, kro...@yahoo.com writes: Subj:IEC 61000-4-2 ESD 61000-4-5 Surge lower levels Date:07/06/02 23:01:43 GMT Daylight Time From:kro...@yahoo.com (w w) Hello all, I'm confused. When preparing an EMC test plan for CE requirements I've been told to narrow in on Generic or Product Standards (which ever is more applicable) to help demonstrate compliance. For example, if testing to EN 55024 ITE immunity, the standard calls for various IEC Basic Standards to be carried out. The severity levels to be perfromed on the EUT is given in the EN 55024 tables. I've always been told that: - The level called out in the Generic/Product standard takes precedent over the the informative- recommended sevrity levels (for a given environment,level 1-4 etc)in the IEC Basic's - The Basic's are only to be used for set-up and how to perfrom the test. Here's the question: In the ESD and Surge standard there is mention in the test methodology that lower levels shall be applied (I don't see this in the EFT, Rad Susc. or Cond RF standards). I have heard comments that only the one set of levels called out in the Generic/Product standard is all that needs to be performed. Then I've also been told from other camps that lower levels MUST be carried out. If the EN 55024 calls for 1,2 kV for surge on the AC, does this mean we have to repeat the test @ .5, 1kV too? For ESD, 8 air, 4 cont should really be 8,6,4,2 air and 4,2,1 cont??
Re: IEC 61000-4-2 ESD 61000-4-5 Surge lower levels
In a message dated 6/7/2002 5:01:43 PM Central Daylight Time, kro...@yahoo.com writes: If the EN 55024 calls for 1,2 kV for surge on the AC, does this mean we have to repeat the test @ .5, 1kV too? For ESD, 8 air, 4 cont should really be 8,6,4,2 air and 4,2,1 cont?? This is indeed the case. When assessing EMC labs, if evidence did not exist this was being done, at least for transient tests, I would write a deficiency. Further, For tests such as surge, I expect to see synchronization with the both zero crossing points, not just the voltage transition from positive to negative. I have seen many failures at lower levels that do not show themselves at higher levels. Derek N. Walton Owner, L. F. Research EMC Design and Test Facility 12790 Route 76, Poplar Grove, IL 61065 www.lfresearch.com
