[PSES] SPC component properties
Brian, I appreciate for your purposes the SPC component of choice is the MOV. Quite right too, if you are considering cost and device safety standards like UL 1449. SPC standards, which tend to be for component electrical and environmental performance, can only overlap the requirements of an Equipment/Device safety standard. Your perception of other protection technologies needs revision. True, PN junction zener breakdown diodes have a very soft clamping characteristic. NB The zener breakdown effect only occurs below about 7 V. To counter the poor zener clamping characteristic a multi-junction silicon semiconductor component using the punch-through effect can be used. This type of technology provides a sharp clamping characteristic from a few volts upwards. Punch-through voltage limiters can be found in Ethernet ports. These SPCs protect the Ethernet PHY chip against damaging overvoltages (even though 5-volts may not sound like an overvoltage) Above 7 V a different breakdown effect comes in -- the avalanche effect. Avalanche breakdown diodes have a good sharp clamping characteristic. You may see them referred to as SADs, Silicon Avalanche Diodes. The three-letter acronym powers that be in the IEC said they didn't want a sad component and so the ABD, Avalanche Breakdown Diode, acronym came into being. Unfortunately, many people, who don't know the difference between zener and avalanche breakdown, call ABDs zeners, which is totally wrong. All PN junction semiconductors have relatively low thermal capacity and energy absorption capability. These deficiencies can be countered by using series and parallel combinations of ABDs. There are several companies in the US making AC Power SPDs using this approach -- costly, but these have a better clamping performance than an MOV. The GDT uses gaseous discharge and the switching time from sparkover to the low-voltage arc can be in the tens of nanoseconds. The problem is that the sparkover voltage is dependent on the rate of voltage rise. This overshoot of surge sparkover to AC sparkover can be something like 2:1. This is not a firm ratio but dependent on the AC/DC sparkover voltage. An 80 V GDT will have a higher surge sparkover voltage than the sweet spot 250 V GDT. An interesting trend I've noticed is for GDT MOV series combinations where PLC is being used. Put MOV protection (read capacitance) on the AC supply and PLC reach and environmental pollution are reduced. Protect using a low capacitance GDT MOV series combination and PLC reach and environmental pollution are maximised. Regards Mick On 14/11/2011 21:04, Brian Oconnell wrote: o further abuse a meme - moar standards! [insert troll-face here] Another member has previously commented that there a several type of components used to arrest a surge. For the purpose of my OP, was focused on a MOV-type SPD as defined under UL CCNs VZCA2 and VZCA8, where the effective standards are UL1449 and CSA C233.1, and various CSA TILs. And of course, the wondrous IEC61051-2. This is another case where EMC requirements (61000-4-5,6) can affect product safety. Last year's update to the 2d ed of 60950-1 for my component power supplies was, for some models, quite an adventure. A problem NOT ADDRESSED by TC108 is the increased energy AFTER a surge, or during a SFC, due to the 120% rating requirement. Perhaps this was a principal intent of UL1449 3d ed - verify that the high E and I do not make the MOV puke it guts and start a fire. There are many sources of increased energy - my two problem children are the effects of an inductive kick to the circuit being 'protected' by the SPD*after* the current interrupt device has opened; and the higher voltage (CV^2), during a surge, at which the SPD will start conducting. As for GDTs - they take longer to get to low Z. And zener-type arrestors do not have a sharp knee at the conduction level. The ZnO MOV seems to be the best chance of survival, assuming the other circuit components can handle much higher coulombs running around before clamping. Moar standards! Moar unintended effects! Moarrr Brian -Original Message- From:emc-p...@ieee.org [mailto:emc-p...@ieee.org]On Behalf Of ralph.mcdiar...@schneider-electric.com Sent: Monday, November 14, 2011 11:31 AM To:EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] MOV requirements Does the industry really need another standard, I wonder? Ralph McDiarmid | Schneider Electric | Renewable Energies Business | CANADA | Regulatory Compliance Engineering From: John Woodgatej...@jmwa.demon.co.uk To:EMC-PSTC@LISTSERV.IEEE.ORG Date: 11/11/2011 06:48 AM Subject: Re: [PSES] MOV requirements In message4ebd2d05.5050...@ieee.org, dated Fri, 11 Nov 2011, Mick Maytumm.j.may...@ieee.org writes: MOV, Varistor, VDR; Metal-Oxide Varistor are all names for a voltage-limiting component using a particular technology. I think this 'particular technology' is an
[PSES] Northeast Product Safety Society Vendor’s Night Tomorrow, November 16th
All, The Northeast Product Safety Society invites you to the 17th annual Vendor’s Night to be held at the Marlborough Holiday Inn next week tomorrow, November 16th from 5:00 to 9:30 PM. Vendor's Night is opportunity to get answers to all your product safety/EMC questions in one evening. There will be up to 50 companies exhibiting. Exhibitors are from certification agencies, qualified testing laboratories, independent consultants and suppliers of services, test equipment and components. If you will be in the area, feel free to join us. Walk-in registration is welcomed. There is no fee to attend. The Vendor’s Night registration opens at 4:30 PM and the Exhibition will be open from 5:00 PM to 9:30 PM. A free, 2 entrée, buffet style dinner will be served during the exhibition from 7:30 PM to 9:00 PM. A Vendor’s Night announcement flyer is available at http://www.nepss.net/17thNPSSFlyer.doc and a Vendor’s Night exhibitor registration form is available at http://www.nepss.net/17thNPSSRegForm.doc on the NPSS web site but we ask you to complete your reservations before Nov 14th. There are still a few tables available for any vendor that would like to participate in the 17th Annual Vendor’s Night. Please feel free to contact Bill Graham at b...@grahamweb.com, Dave Wheeler at inter...@aol.com or myself for more information about Vendor’s Night. There is no charge for admission to the exhibits with complimentary buffet dinner. So that we may plan the dinner, we ask you to make a dinner notice reservation with Donna Kearney at 978-870-5563 (email to dkearn...@hotmail.com) or Matthew Campanella at 508-786-7629 (email to matthew.campane...@motorola.com). In addition to the world class products and varied local services on display this year there will be a prize drawing for those attending. This Prize drawing is restricted to visitors to the show. In addition various companies will have handouts. Please join us at the Holiday Inn on the 16th and network with your many friends and colleagues in the Product Safety and EMC communities in New England, enjoy an evening of good food and perhaps not only come away with a little more product or service information but maybe a little more cash in your pocket. Further information about the Northeast Product Safety Society is available at http://www.nepss.net. An NPSS membership application form with brief NPSS brochure is also available on the NPSS site at http://www.nepss.net/page18.html. The 17th Annual Vendor’s Night location is: Marlborough Holiday Inn 265 Lakeside Avenue Marlborough, MA 01752 (508) 481-3000 Web directions are available at http://www.ichotelsgroup.com/h/d/hi/1/en/hotel/boxma/transportation Directions: From Route 495 North or South, take Exit 24, Route 20 East Turn left into Holiday Inn entrance (approximately 100 feet from Route 495 North) Matt Campanella NPSS Secretary (508) 786-7629 matthew.campane...@motorola.com email - 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. 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] SPC component properties
Mick, Good points, most of which are within the realization of my employer's designs. For example, for the automotive stuff, we tend to not use MOVs, but as you suggested, an avalanche diode(where our big concern is not surge, but ESD). But for component conversion devices, where the rated input will be up 1kV, we do the MOV and/or GDT dance. There are no normative safety requirements for the SELV/PELV input environment for our automotive toys, but for mains-connected stuff - you gotta dance with the component that can party until you puke. Have I used enough crass metaphors? Brian -Original Message- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org]On Behalf Of Mick Maytum Sent: Tuesday, November 15, 2011 6:15 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: SPC component properties Brian, I appreciate for your purposes the SPC component of choice is the MOV. Quite right too, if you are considering cost and device safety standards like UL 1449. SPC standards, which tend to be for component electrical and environmental performance, can only overlap the requirements of an Equipment/Device safety standard. Your perception of other protection technologies needs revision. True, PN junction zener breakdown diodes have a very soft clamping characteristic. NB The zener breakdown effect only occurs below about 7 V. To counter the poor zener clamping characteristic a multi-junction silicon semiconductor component using the punch-through effect can be used. This type of technology provides a sharp clamping characteristic from a few volts upwards. Punch-through voltage limiters can be found in Ethernet ports. These SPCs protect the Ethernet PHY chip against damaging overvoltages (even though 5-volts may not sound like an overvoltage) Above 7 V a different breakdown effect comes in the avalanche effect. Avalanche breakdown diodes have a good sharp clamping characteristic. You may see them referred to as SADs, Silicon Avalanche Diodes. The three-letter acronym powers that be in the IEC said they didnt want a sad component and so the ABD, Avalanche Breakdown Diode, acronym came into being. Unfortunately, many people, who dont know the difference between zener and avalanche breakdown, call ABDs zeners, which is totally wrong. All PN junction semiconductors have relatively low thermal capacity and energy absorption capability. These deficiencies can be countered by using series and parallel combinations of ABDs. There are several companies in the US making AC Power SPDs using this approach costly, but these have a better clamping performance than an MOV. The GDT uses gaseous discharge and the switching time from sparkover to the low-voltage arc can be in the tens of nanoseconds. The problem is that the sparkover voltage is dependent on the rate of voltage rise. This overshoot of surge sparkover to AC sparkover can be something like 2:1. This is not a firm ratio but dependent on the AC/DC sparkover voltage. An 80 V GDT will have a higher surge sparkover voltage than the sweet spot 250 V GDT. An interesting trend Ive noticed is for GDT MOV series combinations where PLC is being used. Put MOV protection (read capacitance) on the AC supply and PLC reach and environmental pollution are reduced. Protect using a low capacitance GDT MOV series combination and PLC reach and environmental pollution are maximised. Regards Mick On 14/11/2011 21:04, Brian Oconnell wrote: o further abuse a meme - moar standards! [insert troll-face here] Another member has previously commented that there a several type of components used to arrest a surge. For the purpose of my OP, was focused on a MOV-type SPD as defined under UL CCNs VZCA2 and VZCA8, where the effective standards are UL1449 and CSA C233.1, and various CSA TILs. And of course, the wondrous IEC61051-2. This is another case where EMC requirements (61000-4-5,6) can affect product safety. Last year's update to the 2d ed of 60950-1 for my component power supplies was, for some models, quite an adventure. A problem NOT ADDRESSED by TC108 is the increased energy AFTER a surge, or during a SFC, due to the 120% rating requirement. Perhaps this was a principal intent of UL1449 3d ed - verify that the high E and I do not make the MOV puke it guts and start a fire. There are many sources of increased energy - my two problem children are the effects of an inductive kick to the circuit being 'protected' by the SPD *after* the current interrupt device has opened; and the higher voltage (CV^2), during a surge, at which the SPD will start conducting. As for GDTs - they take longer to get to low Z. And zener-type arrestors do not have a sharp knee at the conduction level. The ZnO MOV seems to be the best chance of survival, assuming the other circuit components can handle much higher coulombs running around before clamping. Moar standards! Moar unintended effects! Moarrr Brian -Original Message- From: emc-p...@ieee.org
Re: [PSES] AC Powering or not to AC power that is the test option
Brian, I find portions of our discussion has been transcribed to the entire IEC TC 108 group. Thus I feel I should respond to your TC 108 comments A problem NOT ADDRESSED by TC108 is the increased energy AFTER a surge, or during a SFC, due to the 120% rating requirement. Perhaps this was a principal intent of UL1449 3d ed - verify that the high E and I do not make the MOV puke it guts and start a fire. I don't think TC 108 is deficient in missing out AC powering when surging. I'm not in love with some other stuff they do, but that's another discussion. My reasoning is, if the surge damages the MOV, then all the applied AC does is provide a power source to cause a component power loss and temperature rise that might lead to thermal runaway and component destruction. Without the application of AC power, there are measurement techniques available to tell if the component has been damaged. At the component level, measuring the MOV nominal voltage at 1 mA DC is a common approach. If this voltage changes by more than a given amount then the MOV has degraded due to surge. I've spent a deal of time studying UL 1449 recently and, as I understand it, in the most stressful surge test UL doesn't apply AC power (like TC 108). Type 2 SPDs have a Nominal discharge current test (As the MOV isn't a GDT with a gaseous filling, you can't have a discharge current in it, so the correct term is the more mundane nominal surge current). Preferred current values are 3 kA, 5 kA, 10 kA and 20 kA. These are currents in the SPD, not short-circuit ones, produced by an 8/20 current generator. No AC power is applied. Type 3 SPDs have an operating duty cycle test with AC power applied. The surge generator is a 1.2/50-8/20 combination wave generator set for 6 kV open-circuit and 3 kA short-circuit. Once you included the coupling/decoupling network and the component, it is only a quasi-8/20 current of a smaller amplitude than the short-circuit value in the MOV . UL measure pre and post test limiting voltage - this is a very crude validation assessment method. A lot has gone wrong to cause a significant change in limiting voltage. On the bright side, because UL throws a lot of extra tests in, there is a leakage current test, which performs a similar appraisal as the component 1 mA nominal voltage test. 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. 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] CE marking of deep-fat fryer
Ralph, no real argument to the benefit except especially the safety folks won't even go into court as an expert witness on your behalf. But the benefit of the third party is more in how deep they get into your wallet. is the reasonable manufacturer doctrine in Tort law. It's just what it sounds like. Did you meet the minimums of what a reasonable manufacturer would do? E.g. Did you seek a second opinion about the safety or the product? If it is common in the industry to do so and you don't bother then you don't' meet the doctrine and the monetary damages are going to escalate dramatically because you've shown a disregard for you customers safety. - This is all paraphrased and cut down from a seminar on Tort law as it applies to safety many years ago. So the value is a ha' penny versus a pound sterling. From: ralph.mcdiar...@schneider-electric.com [mailto:ralph.mcdiar...@schneider-electric.com] Sent: Tuesday, November 15, 2011 8:51 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] CE marking of deep-fat fryer I don't think UL would be sued; the manufacturer is ultimately liable. The is little or no benefit of 3rd party certification of a product under Tort law. _ Ralph McDiarmid | Schneider Electric | Renewable Energies Business | CANADA | Regulatory Compliance Engineering From: John Woodgate j...@jmwa.demon.co.uk To: EMC-PSTC@LISTSERV.IEEE.ORG Date: 11/14/2011 10:50 PM Subject: Re: [PSES] CE marking of deep-fat fryer In message 4ec19e99.7060...@aol.com, dated Mon, 14 Nov 2011, Derek Walton lfresea...@aol.com writes: I guess I find this nonsense. ANYTHING abused looks dangerous. More examples of Nanny state control. Yes, but if they didn't do it, UL would be sued for $100 by everyone who sets their fryer on fyer. That may happen anyway because the person concerned can't read English. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK Some people who are peeling the finch of the financial crisis are thinking of biting a rook. - 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. 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 MessageLabs Email Security System. __ - 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. 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 - 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. 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] CE marking of deep-fat fryer
From: ralph.mcdiar...@schneider-electric.com [mailto:ralph.mcdiar...@schneider-electric.com] Sent: Tuesday, November 15, 2011 08:51 I don't think UL would be sued; the manufacturer is ultimately liable. The is little or no benefit of 3rd party certification of a product under Tort law. The precedence of tort law is to assign financial responsibility in weighted proportion to the depth of pocket, regardless of actual responsibility or lack thereof. If UL (or any other NRTL) has a safety certification mark on a product used with the offending fryer, even if not a part of the original equipment, it can lead to naming them in a suit. Regards, Peter L. Tarver, PE This email message is for the sole use of the intended recipient(s) and may contain confidential and/or privileged information. If you are not an intended recipient, you may not review, use, copy, disclose or distribute this message. If you received this message in error, please contact the sender by reply email and destroy all copies of the original message. - 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. 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] CE marking of deep-fat fryer
Yup, it's the theory of deep pockets but there still has to be proximal cost for them to drag anybody into the fray UL didn't design it, they didn't sell it, and they didn't tell anybody it was safe - only that it meets the standards for safety that exist at the time of review. I suppose it was a very strong implication though. I've been involved in exactly one case. A monitor in a bank caught fire, the insurance company came after us, and even after showing UL review, proper plastics (at least as far as the current state of product safety was concerned) and pointing out that the fire was caused by an employee who lit a candle near the monitor and forgot to blow it out before she left for the night and was the actual source of the fire our insurance company paid up. Cheaper to pay than to litigate I suppose. But neither then nor any time since then during product recalls or safety accidents, to the best of my knowledge, UL nor any other 3rd party evaluator was every made party to the lawsuit. (I remember a Listed Coffee pot that caught fire and Listed laptops with Li Batteries were bursting in flames and cause injuries for example) Not a lawyer by either trade nor inclination -Original Message- From: John Shinn [mailto:jmsh...@pacbell.net] Sent: Tuesday, November 15, 2011 12:43 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] CE marking of deep-fat fryer Peter is correct. The Lawyers will usually list everyone remotely associated with the product, including the retailer who sold it. John Shinn -Original Message- From: Peter Tarver Sent: Tuesday, November 15, 2011 10:53 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: RE: [PSES] CE marking of deep-fat fryer From: ralph.mcdiar...@schneider-electric.com [mailto:ralph.mcdiar...@schneider-electric.com] Sent: Tuesday, November 15, 2011 08:51 I don't think UL would be sued; the manufacturer is ultimately liable. The is little or no benefit of 3rd party certification of a product under Tort law. The precedence of tort law is to assign financial responsibility in weighted proportion to the depth of pocket, regardless of actual responsibility or lack thereof. If UL (or any other NRTL) has a safety certification mark on a product used with the offending fryer, even if not a part of the original equipment, it can lead to naming them in a suit. Regards, Peter L. Tarver, PE This email message is for the sole use of the intended recipient(s) and may contain confidential and/or privileged information. If you are not an intended recipient, you may not review, use, copy, disclose or distribute this message. If you received this message in error, please contact the sender by reply email and destroy all copies of the original message. - 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. 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://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. 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
