Re: EN61000-3-2:2000 Harmonic current emissions
John, I was looking at my copy of 61000-3-2 to find the references you all are making. My copy does not have a paragraph 6.2.3.3 for example. Then I realized you are referring to EN 61000-3-2 : 2000. What I have is IEC 61000-3-2 : 2000. Can anyone tell me that there is that big a difference between the IEC and EN version of this standard? I have para. 6.2, 6.2.1, 6.2.2, 6.3 and that is all. And, if there is that big a difference between the two, how does that happen? I though EN's were nothing more than approved IEC's? What am I missing 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 02:19 AM 7/25/02 -0400, John Barnes wrote: Neil, If the power supplies are intended for audio equipment, where the peak power required for some types of music can be 10 times the average power, I could buy the manufacturer's explanation. Otherwise their explanation of how they pass EN 61000-3-2:2000 sounds bogus to me. An EN 61000-3-2:2000 harmonics test will usually take between 2.5 minutes and 25 minutes (Section 6.2.4, Test observation period). Beginning 10 seconds after the EUT is turned on (Section 6.2.3.2, Starting and stopping), the harmonic current drawn by the equipment under test (EUT) is measured and analyzed in 1.5-second time chunks (Section 6.2.2, Measurement Procedure). Section 6.2.3.3, Application of limits, specifies that for an individual harmonic current (one frequency), the average over the entire test observation period must be under the specified limit. But the average over a 1.5 second time chunk may exceed the specified limit by up to 50%. This makes more sense when we read Annex C, detailing the test conditions for various types of equipment. Audio amplifiers stand out because of the wide normal variations in output-power, and thus current draw. Similarly, washing machines stand out because certain modes may require stopping and re-starting the motor, and starting an induction motor can draw five to seven times its full-load running current. A brief, infrequent burst of input current is not going to cause overheating of neutral wires or power transformers, which is the major concern of EN 61000-3-2. Do an Internet search for triplen if you would like to read more about this subject. John Barnes dBi Corporation http://www.dbicorporation.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: EN61000-3-2:2000 Harmonic current emissions
Neil, If the power supplies are intended for audio equipment, where the peak power required for some types of music can be 10 times the average power, I could buy the manufacturer's explanation. Otherwise their explanation of how they pass EN 61000-3-2:2000 sounds bogus to me. An EN 61000-3-2:2000 harmonics test will usually take between 2.5 minutes and 25 minutes (Section 6.2.4, Test observation period). Beginning 10 seconds after the EUT is turned on (Section 6.2.3.2, Starting and stopping), the harmonic current drawn by the equipment under test (EUT) is measured and analyzed in 1.5-second time chunks (Section 6.2.2, Measurement Procedure). Section 6.2.3.3, Application of limits, specifies that for an individual harmonic current (one frequency), the average over the entire test observation period must be under the specified limit. But the average over a 1.5 second time chunk may exceed the specified limit by up to 50%. This makes more sense when we read Annex C, detailing the test conditions for various types of equipment. Audio amplifiers stand out because of the wide normal variations in output-power, and thus current draw. Similarly, washing machines stand out because certain modes may require stopping and re-starting the motor, and starting an induction motor can draw five to seven times its full-load running current. A brief, infrequent burst of input current is not going to cause overheating of neutral wires or power transformers, which is the major concern of EN 61000-3-2. Do an Internet search for triplen if you would like to read more about this subject. John Barnes dBi Corporation http://www.dbicorporation.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: EN61000-3-2:2000 Harmonic current emissions
Neil I can't answer your question directly, but..the EMC rules have provisions which allow exclusion of items which draw more than 1kW and or are not for consumer applications. Your power supplies may fall inside these exclusions and therefore may not need EMC evaluation. We have a linear PS in the same situation. I understand in principal one may make a declaration that the EMC does not apply though this has not been followed through. The LVD would still apply. The aim of the EMC Directive is to control pollution of the public supply from multiple low power non-pfc loads such as TV, home computer terminals etc. They can't and don't want to control smaller quantities of commercial loads. Of course you may find that no EMC test house will know about the limitations on EMC application, because it would do them out of a job.nevertheless I am speaking the truth as I know it but cannot quote you chapter and verse. You might find the website of John Woodgate helpful www.jmwa.demon.co.uk he is knowledgable about audio applications. Good Luck Ted Rook Crest Audio Console Div (Brit audio engineer in NJ USA) --- 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
EN61000-3-2:2000 Harmonic current emissions
Hi, We have been using pfc corrected power supplies where each harmonic has met the requirements of EN61000-3-2 Class A limits. Investigating some new ranges of power supplies, we find that some individual harmonic currents exceed the limits. The manufacturers have quoted sections 3Z1, 3Z3, 6.2.3.3 7 as reasons why they pass the requirements of the standard. Can anyone explain in plain English the meaning of these paragraphs with respect to the limits for class A and the measurements of individual harmonics? Many thanks, 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: Harmonic current emissions
Dear Rich Many thanks for your useful analyses. I was wrong to suggest that the 'computer industry' is in denial about mains harmonics - I realise that many people in that industry have made and are making valuable contributions in that field. But I am sure that the claims that there is 'no scientific evidence' for harmonics problems would not stand the light of day. In the UK harmonic problems due to fluorescent lighting have been discussed in public fora since the 1950's, and Arrilaga's important textbook on harmonics was published in 1985. The IEE (based in London) held an international conference on harmonics in power systems in 1981. I haven't costed any PFC designs for a while, but there now appear to be solutions available that have much lower cost then the 'active PFC' front converters we used to use. For example: the 'charge-pump' method, which does not use additional switching devices - see Infineon Application Note: AN-TDA 1684X (version 1.2 dated June 2000) and a (probably) forthcoming article on improving this technique in a future issue of Compliance Engineering Magazine (www.ce-mag.com). Regards, Keith Armstrong In a message dated 23/01/02 20:11:32 GMT Standard Time, ri...@sdd.hp.com writes: Subj:Harmonic current emissions Date:23/01/02 20:11:32 GMT Standard Time From:ri...@sdd.hp.com (Rich Nute) Sender:owner-emc-p...@majordomo.ieee.org Reply-to: A HREF=mailto:ri...@sdd.hp.com;ri...@sdd.hp.com/A (Rich Nute) To:cherryclo...@aol.com CC:ghery.pet...@intel.com, emc-p...@majordomo.ieee.org Hi Keith and Ghery: There are a number of effects of harmonic current emission from non-linear loads. 1) When a large number of loads rich in triplen harmonics are supplied from a 3-phase source, the neutral current can be as high as root 3 of the phase current. (This effect does not exist on a single-phase distribution system, or on a 3-phase system where each phase has its own neutral.) Where the neutral wire is sized for a balanced load, some authorities allow the neutral wire to be one size smaller than the phase wire. Such a wire is likely to be overheated by the triplen currents. Indeed, it is possible to overheat the neutral wire when it is sized the same as the phase wire. In the USA, authorities now require (for such loads) the wire to be larger than the phase wire, or two, parallel neutral wires. 2) Consider that the non-linear load generates current at harmonics of the mains frequency and injects it into the mains distribution system. This current must circulate in the distribution system and return to the source (load). Often, this current circulates in the delta primary of the first upstream delta-wye distribution transformer, and causes the transformer delta winding to overheat. (This effect is likewise mostly due to triplen harmonics.) In the USA, distribution transformers are specially designed to dissipate this power without overheating. Such transformers include a K-factor rating, which is a measure of the transformer to accommodate the current. 3) Depending on the source impedance, a large number of non-linear loads can cause voltage waveform distortion. Voltage distortion is caused by all of the harmonics, not just the triplen harmonics. Voltage waveform distortion can cause motors to overheat. Each of these effects is a separate and independent issue. They should not be lumped as a single issue. For each effect, there can be one or more remedies. The remedy can be either in the load or in the source. EN 61000-3-2 arises from the voltage distortion effect. Mr. Van den Bergh's comments (as quoted by Keith) appear to address voltage distortion, not the other effects. Because of the difference in the design of power distribution systems, voltage distortion is more of a problem in the EU than in the USA. I suspect the real reason for the computer industry's denial of harmonics problems, or else blaming them on a poor distribution system, is that US computer manufacturers simply want to make one model they can sell world-wide so they want whatever is permitted in their main market (the US) to be permitted everywhere else. Would you agree with this? I believe this is an oversimplification of the manufacturer's dilemma of addressing this problem. The USA computer industry has been quite forward in addressing effects 1 and 2. The computer industry was the force behind a series of academia-based seminars on the causes and solutions to effects 1 and 2 that resulted in changes to the USA National Electrical Code and to distribution transformer testing and ratings. (I presented in some of those seminars.) This is NOT denial. But whichever
Re: Harmonic current emissions
I read in !emc-pstc that Rich Nute ri...@sdd.hp.com wrote (in 200201232308.paa21...@epgc264.sdd.hp.com) about 'Harmonic current emissions', on Wed, 23 Jan 2002: The additional cost for a PF-corrected SMPS is not a constant adder; it is proportional to power output. One must use higher power PF components for higher power output. But the whole cost is roughly proportional to power. The figures I quoted refer to 'a normal PC power supply', which I suppose is a 200 or 250 W unit. Having actually purchased production quantities (1995) of the same SMPS in both non-PF-corrected and PF- corrected schemes, the additional cost for PF-corrected ranged from 50% to 75% higher than the non-PF-corrected supply. In 1995, corrected supplies were relatively new and quantities were low. When the CDV for the Millennium Amendment was circulated, we in UK had protests from power supply manufacturers, saying that it undermined their market for corrected supplies, **which they were almost entirely concentrating on**. In fact, of course, the majority of their sales still go into Class D products. More recently (2001), the cost difference was indeed lower -- only about 25-30% premium. That still seems high. How does it compare with my USD figures, though? (;-) I suspect your sources wanted to sell PF-corrected SMPS's and exaggerated on the low side. The figures I quoted did not come from a sales situation but information supplied to the IEC WG. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk After swimming across the Hellespont, I felt like a Hero. PLEASE do NOT copy news posts to me by E-MAIL! --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
Re: Harmonic current emissions
Hi John: But whichever method is adopted, the customer pays the bill eventually and I have more confidence in the highly competitive world of electronic products to come up with a cost-effective solution in a timely manner. One of the USA's major objections to EN61003-2 is that remedying the load repeats with each new product that is introduced, while remedying the source is a one-time remedy. EN61000-3-2 requires continous cost to the consumer with each product. (The cost is NOT trivial -- nearly double the cost of the power supply.) No, that's certainly an exaggeration. We have been told various sums from USD1 to USD5, and I suspect that the lower value is nearer the truth. The additional cost for a PF-corrected SMPS is not a constant adder; it is proportional to power output. One must use higher power PF components for higher power output. Having actually purchased production quantities (1995) of the same SMPS in both non-PF-corrected and PF- corrected schemes, the additional cost for PF-corrected ranged from 50% to 75% higher than the non-PF-corrected supply. More recently (2001), the cost difference was indeed lower -- only about 25-30% premium. I suspect your sources wanted to sell PF-corrected SMPS's and exaggerated on the low side. Rich --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
Re: Harmonic current emissions
I read in !emc-pstc that Rich Nute ri...@sdd.hp.com wrote (in 200201232003.maa21...@epgc264.sdd.hp.com) about 'Harmonic current emissions', on Wed, 23 Jan 2002: Hi Keith and Ghery: There are a number of effects of harmonic current emission from non-linear loads. 1) When a large number of loads rich in triplen harmonics are supplied from a 3-phase source, the neutral current can be as high as root 3 of the phase current. (This effect does not exist on a single-phase distribution system, or on a 3-phase system where each phase has its own neutral.) Consider that the 3rd harmonic current of a high-efficiency single-phase rectifier is near 90% of the fundamental. Then consider that the third harmonic currents *add arithmetically* in the neutral. That give a neutral current of 2.7 times the fundamental current. If you take all the triplen harmonics into account you get a neutral current of 2.85.. times the fundamental current in one phase. [snip] The USA computer industry has been quite forward in addressing effects 1 and 2. The computer industry was the force behind a series of academia-based seminars on the causes and solutions to effects 1 and 2 that resulted in changes to the USA National Electrical Code and to distribution transformer testing and ratings. (I presented in some of those seminars.) This is NOT denial. But whichever method is adopted, the customer pays the bill eventually and I have more confidence in the highly competitive world of electronic products to come up with a cost-effective solution in a timely manner. One of the USA's major objections to EN61003-2 is that remedying the load repeats with each new product that is introduced, while remedying the source is a one-time remedy. EN61000-3-2 requires continous cost to the consumer with each product. (The cost is NOT trivial -- nearly double the cost of the power supply.) No, that's certainly an exaggeration. We have been told various sums from USD1 to USD5, and I suspect that the lower value is nearer the truth. Indeed, this has forced manufacturers to develop one supply for the EU, and one supply for the remainder of the world. And, forced two products for the world instead of one. (One of the benefits of EN61000-3-2 has been a real effort at power reduction so that more and more products are below the 50-watt exemption limit.) 75 W. A change to 50 W would need a new vote by national standards committees, as is clarified in the Millennium Amendment. [snip] -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk After swimming across the Hellespont, I felt like a Hero. PLEASE do NOT copy news posts to me by E-MAIL! --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
Harmonic current emissions
Hi Keith and Ghery: There are a number of effects of harmonic current emission from non-linear loads. 1) When a large number of loads rich in triplen harmonics are supplied from a 3-phase source, the neutral current can be as high as root 3 of the phase current. (This effect does not exist on a single-phase distribution system, or on a 3-phase system where each phase has its own neutral.) Where the neutral wire is sized for a balanced load, some authorities allow the neutral wire to be one size smaller than the phase wire. Such a wire is likely to be overheated by the triplen currents. Indeed, it is possible to overheat the neutral wire when it is sized the same as the phase wire. In the USA, authorities now require (for such loads) the wire to be larger than the phase wire, or two, parallel neutral wires. 2) Consider that the non-linear load generates current at harmonics of the mains frequency and injects it into the mains distribution system. This current must circulate in the distribution system and return to the source (load). Often, this current circulates in the delta primary of the first upstream delta-wye distribution transformer, and causes the transformer delta winding to overheat. (This effect is likewise mostly due to triplen harmonics.) In the USA, distribution transformers are specially designed to dissipate this power without overheating. Such transformers include a K-factor rating, which is a measure of the transformer to accommodate the current. 3) Depending on the source impedance, a large number of non-linear loads can cause voltage waveform distortion. Voltage distortion is caused by all of the harmonics, not just the triplen harmonics. Voltage waveform distortion can cause motors to overheat. Each of these effects is a separate and independent issue. They should not be lumped as a single issue. For each effect, there can be one or more remedies. The remedy can be either in the load or in the source. EN 61000-3-2 arises from the voltage distortion effect. Mr. Van den Bergh's comments (as quoted by Keith) appear to address voltage distortion, not the other effects. Because of the difference in the design of power distribution systems, voltage distortion is more of a problem in the EU than in the USA. I suspect the real reason for the computer industry's denial of harmonics problems, or else blaming them on a poor distribution system, is that US computer manufacturers simply want to make one model they can sell world-wide so they want whatever is permitted in their main market (the US) to be permitted everywhere else. Would you agree with this? I believe this is an oversimplification of the manufacturer's dilemma of addressing this problem. The USA computer industry has been quite forward in addressing effects 1 and 2. The computer industry was the force behind a series of academia-based seminars on the causes and solutions to effects 1 and 2 that resulted in changes to the USA National Electrical Code and to distribution transformer testing and ratings. (I presented in some of those seminars.) This is NOT denial. But whichever method is adopted, the customer pays the bill eventually and I have more confidence in the highly competitive world of electronic products to come up with a cost-effective solution in a timely manner. One of the USA's major objections to EN61003-2 is that remedying the load repeats with each new product that is introduced, while remedying the source is a one-time remedy. EN61000-3-2 requires continous cost to the consumer with each product. (The cost is NOT trivial -- nearly double the cost of the power supply.) Indeed, this has forced manufacturers to develop one supply for the EU, and one supply for the remainder of the world. And, forced two products for the world instead of one. (One of the benefits of EN61000-3-2 has been a real effort at power reduction so that more and more products are below the 50-watt exemption limit.) I have some knowledge of power-factor correction techniques in switch-mode supplies, and some of them can cost very little indeed. So I really don't know why the US computer industry is making such a fuss about controlling harmonic emissions. I certainly have not seen low-cost PF correction techniques. My experience is that the cost is nearly twice the cost of a non-PF corrected power supply. Best regards, Rich ps: EU power suppliers are taking an interesting approach to their customers. If the customer has a linear power factor problem, we will correct it. If the customer has a non-linear power factor problem, we will not correct for it, and we will not sell power to you if the effect is too great. Clearly a monopolistic view.
