Re: [PSES] Hipot with in-circuit voltage limiting devices IEC 61010-1 3rd Ed.
The big deal here is the issue of the energy the varistor must dissipate, which can cause catastrophic failure of the varistor, often resulting in a fire. I have seen this problem, in the lab after hammering a varistor with successive 6000V surge impulses once per minute. In the lifetime of a product connected to residential branch circuit it's uncertain whether it would ever fail. A pound of prevention supposedly being worth an ounce of cure? ___ Ralph McDiarmid | Schneider Electric | Solar Business | CANADA | Regulatory Compliance Engineering From: Richard Nute ri...@ieee.org To: EMC-PSTC@LISTSERV.IEEE.ORG Date: 05/12/2012 05:33 PM Subject: Re: [PSES] Hipot with in-circuit voltage limiting devices IEC 61010-1 3rd Ed. Hi Mick: The problem is the one originally described. The 2nd Edition of IEC 62368-1 is the result of an ad hoc group that studied the various varistor components to arrive at a set of requirements that would allow the varistor (and its derivations) to perform the intended clamping yet not incur a safety issue. The big deal here is the issue of the energy the varistor must dissipate, which can cause catastrophic failure of the varistor, often resulting in a fire. The ad hoc group concentrated on requirements that would prevent device failure. IEC 62368-1 2nd references IEC 61051 for most requirements. I'm sure the varistor requirements will be again reviewed at the upcoming TC108 meeting in June in Northbrook, Illinois, U.S.A. If you or anyone on this list would like to review and comment on the 2nd Edition requirements, send me an e-mail and I'll send you the draft 2nd Edition along with a comment form, and who to send it to. Best regards, Rich -Original Message- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Michael Maytum Sent: Saturday, May 12, 2012 12:01 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Cc: Michael Maytum Subject: Re: [PSES] Hipot with in-circuit voltage limiting devices IEC 61010-1 3rd Ed. Richard, To be clear, what problem and subject correctly are you referring to? The IEC 61010-1 3rd Ed problem is specifying a test voltage of 0.9xclamping voltage. From memory Edition 1 of IEC 62368-1 never specified a test voltage of this level. Yes IEC 62368-1 had a twice AC mains safety test, which links with the twice AC mains test level of IEC 61010-1 3rd Ed. If IEC 62368-1 doesn't have a test level of 0.9xclamping voltage, then, yes, it doesn't have that problem. What is the subject correctly you are referring to; Varistors, safety testing or hipot testing? Best Regards Mick Would you like to check the latest draft of IEC 62368-1 to see if it treats the subject correctly? With respect to this problem, yes, IEC 62368-1 treats the subject correctly. Best regards, Richard Nute - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com __ This email has been scanned by the Symantec Email Security.cloud service
Re: [PSES] Hipot with in-circuit voltage limiting devices IEC 61010-1 3rd Ed.
Richard, To be clear, what problem and subject correctly are you referring to? The IEC 61010-1 3rd Ed problem is specifying a test voltage of 0.9xclamping voltage. From memory Edition 1 of IEC 62368-1 never specified a test voltage of this level. Yes IEC 62368-1 had a twice AC mains safety test, which links with the twice AC mains test level of IEC 61010-1 3rd Ed. If IEC 62368-1 doesn't have a test level of 0.9xclamping voltage, then, yes, it doesn't have that problem. What is the subject correctly you are referring to; Varistors, safety testing or hipot testing? Best Regards Mick Would you like to check the latest draft of IEC 62368-1 to see if it treats the subject correctly? With respect to this problem, yes, IEC 62368-1 treats the subject correctly. Best regards, Richard Nute - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] Hipot with in-circuit voltage limiting devices IEC 61010-1 3rd Ed.
In message 018DCF4B527741149F102EFC42E21D42@RichardHPdv6, dated Fri, 11 May 2012, Richard Nute ri...@bendbroadband.com writes: Would you like to check the latest draft of IEC 62368-1 to see if it treats the subject correctly? With respect to this problem, yes, IEC 62368-1 treats the subject correctly. So it could be used as evidence to persuade TC66 to reconsider. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk Instead of saying that the government is doing too little, too late or too much, too early, say they've got is exactly right, thus throwing them into total confusion. John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] Hipot with in-circuit voltage limiting devices IEC 61010-1 3rd Ed.
Hi Mick: The problem is the one originally described. The 2nd Edition of IEC 62368-1 is the result of an ad hoc group that studied the various varistor components to arrive at a set of requirements that would allow the varistor (and its derivations) to perform the intended clamping yet not incur a safety issue. The big deal here is the issue of the energy the varistor must dissipate, which can cause catastrophic failure of the varistor, often resulting in a fire. The ad hoc group concentrated on requirements that would prevent device failure. IEC 62368-1 2nd references IEC 61051 for most requirements. I'm sure the varistor requirements will be again reviewed at the upcoming TC108 meeting in June in Northbrook, Illinois, U.S.A. If you or anyone on this list would like to review and comment on the 2nd Edition requirements, send me an e-mail and I'll send you the draft 2nd Edition along with a comment form, and who to send it to. Best regards, Rich -Original Message- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Michael Maytum Sent: Saturday, May 12, 2012 12:01 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Cc: Michael Maytum Subject: Re: [PSES] Hipot with in-circuit voltage limiting devices IEC 61010-1 3rd Ed. Richard, To be clear, what problem and subject correctly are you referring to? The IEC 61010-1 3rd Ed problem is specifying a test voltage of 0.9xclamping voltage. From memory Edition 1 of IEC 62368-1 never specified a test voltage of this level. Yes IEC 62368-1 had a twice AC mains safety test, which links with the twice AC mains test level of IEC 61010-1 3rd Ed. If IEC 62368-1 doesn't have a test level of 0.9xclamping voltage, then, yes, it doesn't have that problem. What is the subject correctly you are referring to; Varistors, safety testing or hipot testing? Best Regards Mick Would you like to check the latest draft of IEC 62368-1 to see if it treats the subject correctly? With respect to this problem, yes, IEC 62368-1 treats the subject correctly. Best regards, Richard Nute - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] Hipot with in-circuit voltage limiting devices IEC 61010-1 3rd Ed.
Hello John: With respect to this problem, yes, IEC 62368-1 treats the subject correctly. So it could be used as evidence to persuade TC66 to reconsider. Yes. The 2nd Edition of IEC 62368-1 refers to IEC 61051. TC66 should first identify the safety issue associated with varistors (fire) and the causes of varistor conflagration. Then, TC66 should apply those requirements from IEC 61051 that are likely to prevent conflagration as well as prevent spread of fire in the event of conflagration of the varistor. Best regards, Richard Nute Product Safety Consultant Bend, Oregon, U.S.A. - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] Hipot with in-circuit voltage limiting devices IEC 61010-1 3rd Ed.
Doug, I have received a reply from TC 66 that they will consider the clause F.3.2 problem at their next meeting in October. They have acknowledge that the usage of the term “clamping voltage” is imprecise. They would be receptive to any further inputs on this matter. I used the IEC system to send the message below to the chair and secretary about F.3.2. SNIP A question has come up in the IEEE Product Safety Engineering Society about the requirements of clause F.3.2. As I understand it the hipot test is done at “0.9 times the clamping voltage of the voltage limiter” and not less than twice the working voltage. The second requirement is clear for AC of 230V rms equipment a test voltage of at least 460 V rms with a 650 V peak must be used. The first requirement, 0.9xclamping voltage breaks the laws of physics for MOV voltage limiters. The two specific voltages at high and low currents for an MOV clamping/limiting characteristic are: IEC 61643-331, ed. 1.0 (2003-05) clamping voltage peak voltage across the MOV measured under conditions of a specified peak pulse current and specified waveform (Normally an 8/20 impulse is used) IEC 61643-331, ed. 1.0 (2003-05) nominal varistor voltage voltage across the MOV measured at a specified pulsed current, of specific duration NOTE The MOV manufacturer specifies the current. Otherwise, 1 mA is normally used. The pulse duration should be less than 40 ms, unless otherwise specified. In general, nominal value ±10 % is specified by the manufacturer. Let me explain, for a catalogue AC 230 V rms MOV the nominal voltage might be 473 V and the 8/20 clamping voltage 710 V. From these figures you can see that applying 0.9xclamping voltage = 0.9x710 = 630 V would cause substantial current flow in the MOV because it is far above the 1 mA 473 V nominal voltage! Whoever wrote this did not use the correct terminology. To avoid breaking the laws of physics the statement might better read “0.9 times the nominal voltage of the voltage limiter” To just satisfy both requirements the MOV would then require a 650 V/0.9 = 720 V nominal voltage. Of course, there are some more costly ways round this by using a series GDT MOV combination, but then term clamping voltage is incorrect for switching type combinations. I request you discuss this with your members. Regards Michael J Maytum SC 37B Chair SNIP Regards Mick - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] Hipot with in-circuit voltage limiting devices IEC 61010-1 3rd Ed.
In message 5168965687470166.wa.mjmaytumgmail@listserv.ieee.org, dated Fri, 11 May 2012, Michael Maytum mjmay...@gmail.com writes: I have received a reply from TC 66 that they will consider the clause F.3.2 problem at their next meeting in October. They have acknowledge that the usage of the term “clamping voltage” is imprecise. They would be receptive to any further inputs on this matter. Would you like to check the latest draft of IEC 62368-1 to see if it treats the subject correctly? -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk Instead of saying that the government is doing too little, too late or too much, too early, say they've got is exactly right, thus throwing them into total confusion. John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] Hipot with in-circuit voltage limiting devices IEC 61010-1 3rd Ed.
John I would be interested to see the latest draft of IEC 62368-1. I assume this is Edition 2. On surge protective components the original IEC 62368 introduced a safety test run at twice the the nominal AC voltage with decreasing values of series resistance. I would like to see a similar test run on MOV components that incorporate a thermal disconnect, in fact I can make it so. Both IEC 62368-1 and IEC 61010-1 use the term varistor If you look up varistor you find IEV ref 151-13-23 varistor resistor the resistance of which is strongly varying with the applied voltage Varistor and VDR can be applied to a range of components such as MOVs, Avalanche Breakdown Diodes, Zener Breakdown Diodes and Punch-through Diodes. Yet most times when the above standards use varistor they really mean MOV. This colloquial use of varistor can lead to confusion in other language versions. The IEC has a mechanism to catch such inexactitudes - copy the appropriate SC for the topic being discussed. Unfortunately neither TC 66 or TC 108 allow SC 37B access to their documents. Regards Mick John Woodgate j...@jmwa.demon.co.uk writes: I have received a reply from TC 66 that they will consider the clause F.3.2 problem at their next meeting in October. They have acknowledge that the usage of the term “clamping voltage” is imprecise. They would be receptive to any further inputs on this matter. Would you like to check the latest draft of IEC 62368-1 to see if it treats the subject correctly? -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk Instead of saying that the government is doing too little, too late or too much, too early, say they've got is exactly right, thus throwing them into total confusion. John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] Hipot with in-circuit voltage limiting devices IEC 61010-1 3rd Ed.
Would you like to check the latest draft of IEC 62368-1 to see if it treats the subject correctly? With respect to this problem, yes, IEC 62368-1 treats the subject correctly. Best regards, Richard Nute Product Safety Consultant Bend, Oregon, U.S.A. - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] Hipot with in-circuit voltage limiting devices IEC 61010-1 3rd Ed.
Doug, My previous message gave the IEC rulings - terms clamping voltage and nominal varistor voltage - for two specific points on the MOV clamping (clipping) characteristic. For completeness IEC 61010-1, ed. 3.0 (2010-06) defines the following: *working voltage * highest r.m.s. value of the a.c. or d.c. voltage across any particular insulation which can occur when the equipment is supplied at rated voltage NOTE 1 Transients and voltage fluctuations are not considered to be part of the working voltage. NOTE 2 Both open-circuit conditions and normal operating conditions are taken into account. I'm now giving an opinion. Your (nominal) AC supply is 230V rms. The phase not less than twice the working voltage. means the hipot test is done with an AC value of at least 460 V rms or 650 V pk. The hipot test voltage of 0.9 times the clamping voltage of the MOV is clearly crazy, as from your figures of 710 V clamping voltage and 473 V nominal varistor voltage, testing at 0.9x710 = 630 V would cause substantial current in the MOV. One could skate round this and say that the 1 mA nominal varistor voltage is the clamping/threshold/ voltage - a new term - and use an MOV or combination of MOVs to have a nominal voltage of 650/0.9 = 720 V. Sounds like a letter to the Chair and Secretary of TC 66 is needed to resolve this matter. Regards Mick On 10/05/2012 00:27, Doug Powell wrote: A change was made in 3rd Ed. for routine mains hipot tests while clamping devices are still in the circuit; specifically clause F.3.2 (Ed. 3). The standard states the test can be carried out at 0.9 times the clamping voltage of the device and not less than twice the working voltage. Edition 2 said not less than that of the working voltage. My application is 230Vac and I initially selected 275Vrms MOVs. Plugging in the F.3.2 equations, I get a hipot failure. These devices have a very soft voltage knee and as a result of the dynamic resistance, the knee very time dependent. The MOV supplier states the maximum clamping voltage using the 8/20 mS surge is 710V and the DC clamping voltage with a 1 mA current source is 473V. I would assume the 473V is very similar to the peak of the 275 Vrms 50/60 Hz waveform, plus some headroom for component tolerance (~18%). If you try running the numbers to re-select a different MOV value, it is very possible to get all tied up in knots. So, which clamping voltage are we to use? My thought is to use 2 x 230 = 460V and select the next higher MOV from the catalog. Opinions, rulings, decrees from on high? -- Thanks, -doug Douglas E Powell doug...@gmail.com mailto:doug...@gmail.com http://www.linkedin.com/in/dougp01 - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org mailto:emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net mailto:emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org mailto:mcantw...@ieee.org For policy questions, send mail to: Jim Bacher j.bac...@ieee.org mailto:j.bac...@ieee.org David Heald dhe...@gmail.com mailto:dhe...@gmail.com - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] Hipot with in-circuit voltage limiting devices IEC 61010-1 3rd Ed.
Mick, Sorry I didn't review this email before I just sent my last. Clearly you see the same problem as I. I have to wonder if the committee in reviewing this clause only used data sheets and did not validate in the lab. Or is it possibly the committee members just missed this? I would like to suggest the Vclamp we should use this the 8 mS / 10 mS rating. That's mS, not uS. -- Thanks, -doug Douglas E Powell doug...@gmail.com http://www.linkedin.com/in/dougp01 On Thu, May 10, 2012 at 6:58 AM, Mick Maytum m.j.may...@ieee.org wrote: Doug, My previous message gave the IEC rulings - terms clamping voltage and nominal varistor voltage - for two specific points on the MOV clamping (clipping) characteristic. For completeness IEC 61010-1, ed. 3.0 (2010-06) defines the following: *working voltage * highest r.m.s. value of the a.c. or d.c. voltage across any particular insulation which can occur when the equipment is supplied at rated voltage NOTE 1 Transients and voltage fluctuations are not considered to be part of the working voltage. NOTE 2 Both open-circuit conditions and normal operating conditions are taken into account. I'm now giving an opinion. Your (nominal) AC supply is 230V rms. The phase not less than twice the working voltage. means the hipot test is done with an AC value of at least 460 V rms or 650 V pk. The hipot test voltage of 0.9 times the clamping voltage of the MOV is clearly crazy, as from your figures of 710 V clamping voltage and 473 V nominal varistor voltage, testing at 0.9x710 = 630 V would cause substantial current in the MOV. One could skate round this and say that the 1 mA nominal varistor voltage is the clamping* threshold* voltage - a new term - and use an MOV or combination of MOVs to have a nominal voltage of 650/0.9 = 720 V. Sounds like a letter to the Chair and Secretary of TC 66 is needed to resolve this matter. Regards Mick On 10/05/2012 00:27, Doug Powell wrote: A change was made in 3rd Ed. for routine mains hipot tests while clamping devices are still in the circuit; specifically clause F.3.2 (Ed. 3). The standard states the test can be carried out at 0.9 times the clamping voltage of the device and not less than twice the working voltage. Edition 2 said not less than that of the working voltage. My application is 230Vac and I initially selected 275Vrms MOVs. Plugging in the F.3.2 equations, I get a hipot failure. These devices have a very soft voltage knee and as a result of the dynamic resistance, the knee very time dependent. The MOV supplier states the maximum clamping voltage using the 8/20 mS surge is 710V and the DC clamping voltage with a 1 mA current source is 473V. I would assume the 473V is very similar to the peak of the 275 Vrms 50/60 Hz waveform, plus some headroom for component tolerance (~18%). If you try running the numbers to re-select a different MOV value, it is very possible to get all tied up in knots. So, which clamping voltage are we to use? My thought is to use 2 x 230 = 460V and select the next higher MOV from the catalog. Opinions, rulings, decrees from on high? -- Thanks, -doug Douglas E Powell doug...@gmail.com http://www.linkedin.com/in/dougp01 - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher j.bac...@ieee.org David Heald dhe...@gmail.com - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send
Re: [PSES] Hipot with in-circuit voltage limiting devices IEC 61010-1 3rd Ed.
In message CAByvTVN7XfQWJQQFE0hzQv7QfDpzN9G6ykcTQ1gr=2ofguf...@mail.gmail.com, dated Thu, 10 May 2012, Doug Powell doug...@gmail.com writes: I would put a graphical clip of the curves in this email with areas of concern highlighted except I remember this is prohibited on the listserv. You could put them on a web site and tell us where. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk Instead of saying that the government is doing too little, too late or too much, too early, say they've got is exactly right, thus throwing them into total confusion. John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] Hipot with in-circuit voltage limiting devices IEC 61010-1 3rd Ed.
Doug, I wouldn't credit the TC 66 has having MOV component knowledge, just perceptions. Since my last message I have sent messages to the Chair and Secretary of TC 66 wearing my IEC SC 37B chair hat. I was restrained for a change, merely stating they were breaking the laws of physics for MOVs rather than crazy! I suggested that if the 0.9 factor was to work it should be applied to the nominal voltage not the clamping voltage. I'll keep you informed of developments if any. Regards Mick On 10/05/2012 15:15, Doug Powell wrote: Mick, Sorry I didn't review this email before I just sent my last. Clearly you see the same problem as I. I have to wonder if the committee in reviewing this clause only used data sheets and did not validate in the lab. Or is it possibly the committee members just missed this? I would like to suggest the Vclamp we should use this the 8 mS / 10 mS rating. That's mS, not uS. -- Thanks, -doug Douglas E Powell doug...@gmail.com mailto:doug...@gmail.com http://www.linkedin.com/in/dougp01 On Thu, May 10, 2012 at 6:58 AM, Mick Maytum m.j.may...@ieee.org mailto:m.j.may...@ieee.org wrote: Doug, My previous message gave the IEC rulings - terms clamping voltage and nominal varistor voltage - for two specific points on the MOV clamping (clipping) characteristic. For completeness IEC 61010-1, ed. 3.0 (2010-06) defines the following: *working voltage * highest r.m.s. value of the a.c. or d.c. voltage across any particular insulation which can occur when the equipment is supplied at rated voltage NOTE 1 Transients and voltage fluctuations are not considered to be part of the working voltage. NOTE 2 Both open-circuit conditions and normal operating conditions are taken into account. I'm now giving an opinion. Your (nominal) AC supply is 230V rms. The phase not less than twice the working voltage. means the hipot test is done with an AC value of at least 460 V rms or 650 V pk. The hipot test voltage of 0.9 times the clamping voltage of the MOV is clearly crazy, as from your figures of 710 V clamping voltage and 473 V nominal varistor voltage, testing at 0.9x710 = 630 V would cause substantial current in the MOV. One could skate round this and say that the 1 mA nominal varistor voltage is the clamping/threshold/ voltage - a new term - and use an MOV or combination of MOVs to have a nominal voltage of 650/0.9 = 720 V. Sounds like a letter to the Chair and Secretary of TC 66 is needed to resolve this matter. Regards Mick - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] Hipot with in-circuit voltage limiting devices IEC 61010-1 3rd Ed.
F.3.2 says, ...test of F.3.1 can be carried out.. Because it says can and not shall does this make this test optional? Doesn't the previous version of this standard allow you to disconnect surge suppressors during the HiPot test? The Other Brian From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Mick Maytum Sent: Thursday, May 10, 2012 12:00 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Cc: Doug Powell Subject: Re: [PSES] Hipot with in-circuit voltage limiting devices IEC 61010-1 3rd Ed. Doug, I wouldn't credit the TC 66 has having MOV component knowledge, just perceptions. Since my last message I have sent messages to the Chair and Secretary of TC 66 wearing my IEC SC 37B chair hat. I was restrained for a change, merely stating they were breaking the laws of physics for MOVs rather than crazy! I suggested that if the 0.9 factor was to work it should be applied to the nominal voltage not the clamping voltage. I'll keep you informed of developments if any. Regards Mick On 10/05/2012 15:15, Doug Powell wrote: Mick, Sorry I didn't review this email before I just sent my last. Clearly you see the same problem as I. I have to wonder if the committee in reviewing this clause only used data sheets and did not validate in the lab. Or is it possibly the committee members just missed this? I would like to suggest the Vclamp we should use this the 8 mS / 10 mS rating. That's mS, not uS. -- Thanks, -doug Douglas E Powell doug...@gmail.commailto:doug...@gmail.com http://www.linkedin.com/in/dougp01 On Thu, May 10, 2012 at 6:58 AM, Mick Maytum m.j.may...@ieee.orgmailto:m.j.may...@ieee.org wrote: Doug, My previous message gave the IEC rulings - terms clamping voltage and nominal varistor voltage - for two specific points on the MOV clamping (clipping) characteristic. For completeness IEC 61010-1, ed. 3.0 (2010-06) defines the following: working voltage highest r.m.s. value of the a.c. or d.c. voltage across any particular insulation which can occur when the equipment is supplied at rated voltage NOTE 1 Transients and voltage fluctuations are not considered to be part of the working voltage. NOTE 2 Both open-circuit conditions and normal operating conditions are taken into account. I'm now giving an opinion. Your (nominal) AC supply is 230V rms. The phase not less than twice the working voltage. means the hipot test is done with an AC value of at least 460 V rms or 650 V pk. The hipot test voltage of 0.9 times the clamping voltage of the MOV is clearly crazy, as from your figures of 710 V clamping voltage and 473 V nominal varistor voltage, testing at 0.9x710 = 630 V would cause substantial current in the MOV. One could skate round this and say that the 1 mA nominal varistor voltage is the clamping threshold voltage - a new term - and use an MOV or combination of MOVs to have a nominal voltage of 650/0.9 = 720 V. Sounds like a letter to the Chair and Secretary of TC 66 is needed to resolve this matter. Regards Mick - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.orgmailto:emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.netmailto:emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.orgmailto:mcantw...@ieee.org For policy questions, send mail to: Jim Bacher j.bac...@ieee.orgmailto:j.bac...@ieee.org David Heald dhe...@gmail.commailto:dhe...@gmail.com LECO Corporation Notice: This communication may contain confidential information intended for the named recipient(s) only. If you received this by mistake, please destroy it and notify us of the error. Thank you. - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail
Re: [PSES] Hipot with in-circuit voltage limiting devices IEC 61010-1 3rd Ed.
In message 64D32EE8B9CBDD44963ACB076A5F6ABB0261DE06@Mailbox-Tech.lecotech.local, dated Thu, 10 May 2012, Kunde, Brian brian_ku...@lecotc.com writes: F.3.2 says, ...test of F.3.1 can be carried out.. Because it says can and not shall does this make this test optional? It seems, from the limited context you give, that the *method* is optional, but *a* test is mandatory. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk Instead of saying that the government is doing too little, too late or too much, too early, say they've got is exactly right, thus throwing them into total confusion. John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] Hipot with in-circuit voltage limiting devices IEC 61010-1 3rd Ed.
Yes, but in this case, disconnection is not an option. Thanks, -doug Douglas E Powell doug...@gmail.com http://www.linkedin.com/in/dougp01 On Thu, May 10, 2012 at 1:52 PM, Kunde, Brian brian_ku...@lecotc.comwrote: F.3.2 says, “…test of F.3.1 *can* be carried out…..”. Because it says “can” and not “shall” does this make this test optional? Doesn’t the previous version of this standard allow you to disconnect surge suppressors during the HiPot test? The Other Brian *From:* emc-p...@ieee.org [mailto:emc-p...@ieee.org] *On Behalf Of *Mick Maytum *Sent:* Thursday, May 10, 2012 12:00 PM *To:* EMC-PSTC@LISTSERV.IEEE.ORG *Cc:* Doug Powell *Subject:* Re: [PSES] Hipot with in-circuit voltage limiting devices IEC 61010-1 3rd Ed. Doug, I wouldn't credit the TC 66 has having MOV component knowledge, just perceptions. Since my last message I have sent messages to the Chair and Secretary of TC 66 wearing my IEC SC 37B chair hat. I was restrained for a change, merely stating they were breaking the laws of physics for MOVs rather than crazy! I suggested that if the 0.9 factor was to work it should be applied to the nominal voltage not the clamping voltage. I'll keep you informed of developments if any. Regards Mick On 10/05/2012 15:15, Doug Powell wrote: Mick, Sorry I didn't review this email before I just sent my last. Clearly you see the same problem as I. I have to wonder if the committee in reviewing this clause only used data sheets and did not validate in the lab. Or is it possibly the committee members just missed this? I would like to suggest the Vclamp we should use this the 8 mS / 10 mS rating. That's mS, not uS. -- Thanks, -doug Douglas E Powell doug...@gmail.com http://www.linkedin.com/in/dougp01 On Thu, May 10, 2012 at 6:58 AM, Mick Maytum m.j.may...@ieee.org wrote: Doug, My previous message gave the IEC rulings - terms clamping voltage and nominal varistor voltage - for two specific points on the MOV clamping (clipping) characteristic. For completeness IEC 61010-1, ed. 3.0 (2010-06) defines the following: *working voltage * highest r.m.s. value of the a.c. or d.c. voltage across any particular insulation which can occur when the equipment is supplied at rated voltage NOTE 1 Transients and voltage fluctuations are not considered to be part of the working voltage. NOTE 2 Both open-circuit conditions and normal operating conditions are taken into account. I'm now giving an opinion. Your (nominal) AC supply is 230V rms. The phase not less than twice the working voltage. means the hipot test is done with an AC value of at least 460 V rms or 650 V pk. The hipot test voltage of 0.9 times the clamping voltage of the MOV is clearly crazy, as from your figures of 710 V clamping voltage and 473 V nominal varistor voltage, testing at 0.9x710 = 630 V would cause substantial current in the MOV. One could skate round this and say that the 1 mA nominal varistor voltage is the clamping* threshold* voltage - a new term - and use an MOV or combination of MOVs to have a nominal voltage of 650/0.9 = 720 V. Sounds like a letter to the Chair and Secretary of TC 66 is needed to resolve this matter. Regards Mick - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher j.bac...@ieee.org David Heald dhe...@gmail.com -- *LECO Corporation Notice:* This communication may contain confidential information intended for the named recipient(s) only. If you received this by mistake, please destroy it and notify us of the error. Thank you. - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to LT; emc-p...@ieee.orgGT; All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http
Re: [PSES] Hipot with in-circuit voltage limiting devices IEC 61010-1 3rd Ed.
The routine voltage test on mains is mandatory, but the method has options. This is how I read the standard. -- Thanks, -doug Douglas E Powell doug...@gmail.com http://www.linkedin.com/in/dougp01 On Thu, May 10, 2012 at 2:04 PM, John Woodgate j...@jmwa.demon.co.uk wrote: In message **64D32EE8B9CBDD44963ACB076A5F6A**BB0261DE06@Mailbox-Tech.**lecotech.local, dated Thu, 10 May 2012, Kunde, Brian brian_ku...@lecotc.com writes: F.3.2 says, ...test of F.3.1 can be carried out.. Because it says can and not shall does this make this test optional? It seems, from the limited context you give, that the *method* is optional, but *a* test is mandatory. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk Instead of saying that the government is doing too little, too late or too much, too early, say they've got is exactly right, thus throwing them into total confusion. John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - --**--** This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-**pstc.htmlhttp://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.**ieee.org/http://product-compliance.oc.ieee.org/can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/**request/user-guide.htmlhttp://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/**listrules.htmlhttp://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
[PSES] Hipot with in-circuit voltage limiting devices IEC 61010-1 3rd Ed.
A change was made in 3rd Ed. for routine mains hipot tests while clamping devices are still in the circuit; specifically clause F.3.2 (Ed. 3). The standard states the test can be carried out at 0.9 times the clamping voltage of the device and not less than twice the working voltage. Edition 2 said not less than that of the working voltage. My application is 230Vac and I initially selected 275Vrms MOVs. Plugging in the F.3.2 equations, I get a hipot failure. These devices have a very soft voltage knee and as a result of the dynamic resistance, the knee very time dependent. The MOV supplier states the maximum clamping voltage using the 8/20 mS surge is 710V and the DC clamping voltage with a 1 mA current source is 473V. I would assume the 473V is very similar to the peak of the 275 Vrms 50/60 Hz waveform, plus some headroom for component tolerance (~18%). If you try running the numbers to re-select a different MOV value, it is very possible to get all tied up in knots. So, which clamping voltage are we to use? My thought is to use 2 x 230 = 460V and select the next higher MOV from the catalog. Opinions, rulings, decrees from on high? -- Thanks, -doug Douglas E Powell doug...@gmail.com http://www.linkedin.com/in/dougp01 - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] Hipot with in-circuit voltage limiting devices IEC 61010-1 3rd Ed.
Clamping voltage is the MOV voltage under specified surge conditions. Typically that will be an 8/20 impulse. IEC 61643-331, ed. 1.0 (2003-05) clamping voltage VC peak voltage across the MOV measured under conditions of a specified peak pulse current (IP) and specified waveform Your 1 mA voltage is called the nominal voltage (not clamping voltage) when the MOV draws a specified low-level current. IEC 61643-331, ed. 1.0 (2003-05) nominal varistor voltage VN voltage across the MOV measured at a specified pulsed current (IN), of specific duration NOTE The MOV manufacturer specifies the current. Otherwise, 1 mA is normally used. The pulse duration should be less than 40 ms, unless otherwise specified. In general, nominal value ±10 % is specified by the manufacturer. Regards Mick On 10/05/2012 00:27, Doug Powell wrote: A change was made in 3rd Ed. for routine mains hipot tests while clamping devices are still in the circuit; specifically clause F.3.2 (Ed. 3). The standard states the test can be carried out at 0.9 times the clamping voltage of the device and not less than twice the working voltage. Edition 2 said not less than that of the working voltage. My application is 230Vac and I initially selected 275Vrms MOVs. Plugging in the F.3.2 equations, I get a hipot failure. These devices have a very soft voltage knee and as a result of the dynamic resistance, the knee very time dependent. The MOV supplier states the maximum clamping voltage using the 8/20 mS surge is 710V and the DC clamping voltage with a 1 mA current source is 473V. I would assume the 473V is very similar to the peak of the 275 Vrms 50/60 Hz waveform, plus some headroom for component tolerance (~18%). If you try running the numbers to re-select a different MOV value, it is very possible to get all tied up in knots. So, which clamping voltage are we to use? My thought is to use 2 x 230 = 460V and select the next higher MOV from the catalog. Opinions, rulings, decrees from on high? -- Thanks, -doug Douglas E Powell doug...@gmail.com mailto:doug...@gmail.com http://www.linkedin.com/in/dougp01 - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org mailto:emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net mailto:emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org mailto:mcantw...@ieee.org For policy questions, send mail to: Jim Bacher j.bac...@ieee.org mailto:j.bac...@ieee.org David Heald dhe...@gmail.com mailto:dhe...@gmail.com - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
