Re: Unity power factor
Hi Neil: > All I get on visiting the site is "404 Page not found error" on their > home page. Access to all other pages seems to be ok. Using their search > engine facility does not seem to find anything with respect to > application notes or harmonics. Anyone else have this problem? Sorry about the bad reference. Try: http://www.fluke.com/ElectricalPower/El ctrical_register.asp?AGID=3&SID=103&redir=/electricalpower/appnotes.asp If this doesn't work, go to the home page: http://www.fluke.com/ Then, just work your way through the site until you find electrical power application notes. The title of the app note is: "In Tune with Power Harmonics." Good luck and best regards, 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: 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 Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Unity power factor
With reference to the Fluke Application Note suggested by Rich and commented on by John. All I get on visiting the site is "404 Page not found error" on their home page. Access to all other pages seems to be ok. Using their search engine facility does not seem to find anything with respect to application notes or harmonics. Anyone else have this problem? Regards, Neil Helsby ** This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the system manager. This footnote also confirms that this email message has been swept by MIMEsweeper for the presence of computer viruses. www.mimesweeper.com ** This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: Unity Power Factor
I read in !emc-pstc that Rich Nute wrote (in <200301311805.kaa24...@epgc264.sdd.hp.com>) about 'Unity Power Factor' on Fri, 31 Jan 2003: > > > >Hi John: > > >> >Yes, delta-wye distribution transformer overheating >> >does occur due to the circulation and dissipation of >> >the triplen harmonics in the primary (delta) winding. >> >> Thank you for that and the rest of the information, which could prove to >> be very helpful indeed. I would like to use it in my continuing efforts >> to defuse the arguments between the former TC74 experts in TC108 and the >> SC77A/WG1 people. May I say that the information came from you >> (personally, of course, not from HP)? > >Actually, I learned this and other facts about harmonics >from my participation, some years ago, in the CBEMA >(now ITIC) ESC-3 committee. The minutes of those >meetings (whereever they may be) would support my >assertions. Yes, wherever they may be. But I *have* your explanations, and the TC108 members who lurk here will already have seen them. But I need your permission to attribute your texts to a larger audience. Please? > >My understanding of the European situation is that up to >600 homes could be on one distribution transformer, It could be 2000 in some urban areas, AIUI. > and >that the power is distributed as three phases with one >neutral. Yes. >The cumulation of harmonics on such a system >would indeed tend to flat-top the voltage waveform for >those homes that are far from the transformer. Also, >the harmonics would tend to overheat the primary of the >distribution transformer, the failure of which would >cause a much larger outage than in North America. Yes; transformers tend to be more robust that PF compensation capacitors connected at MV, which suffer over-current failure or degradation. But the local one here gets 'fragrantly' warm during summer evenings. > >Likewise, in Europe, within commercial and industrial >sites, the distribution transformer is comparatively >large, and supplies a very much greater load. > Yes. 500 kVA is normal, 1 MVA is not unusual and 2 MVA is not unknown, AIUI. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Interested in professional sound reinforcement and distribution? Then go to http://www.isce.org.uk PLEASE do NOT copy news posts to me by E-MAIL! This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: Unity Power Factor
I read in !emc-pstc that Rich Nute wrote (in <200301311957.laa25...@epgc264.sdd.hp.com>) about 'Unity Power Factor' on Fri, 31 Jan 2003: >Fluke has a good explanation of the deleterious >effects of harmonics. See: > >http://www.fluke.com/ElectricPower/elec.asp Thank you. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Interested in professional sound reinforcement and distribution? Then go to http://www.isce.org.uk PLEASE do NOT copy news posts to me by E-MAIL! This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: Unity Power Factor
Hi John: > Thank you for that and the rest of the information, which could prove to > be very helpful indeed. I would like to use it in my continuing efforts > to defuse the arguments between the former TC74 experts in TC108 and the > SC77A/WG1 people. May I say that the information came from you > (personally, of course, not from HP)? Fluke has a good explanation of the deleterious effects of harmonics. See: http://www.fluke.com/ElectricPower/elec.asp Click on "Application Notes." This will take you to a registration page which you must complete before you can get to the App Note. After registering, click on "In tune with harmonics." This App Note covers a number of effects of harmonic currents that I have not discussed. Best regards, 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: 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 Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: Unity Power Factor
Hi John: > >Yes, delta-wye distribution transformer overheating > >does occur due to the circulation and dissipation of > >the triplen harmonics in the primary (delta) winding. > > Thank you for that and the rest of the information, which could prove to > be very helpful indeed. I would like to use it in my continuing efforts > to defuse the arguments between the former TC74 experts in TC108 and the > SC77A/WG1 people. May I say that the information came from you > (personally, of course, not from HP)? Actually, I learned this and other facts about harmonics >from my participation, some years ago, in the CBEMA (now ITIC) ESC-3 committee. The minutes of those meetings (whereever they may be) would support my assertions. My understanding of the European situation is that up to 600 homes could be on one distribution transformer, and that the power is distributed as three phases with one neutral. The cumulation of harmonics on such a system would indeed tend to flat-top the voltage waveform for those homes that are far from the transformer. Also, the harmonics would tend to overheat the primary of the distribution transformer, the failure of which would cause a much larger outage than in North America. Likewise, in Europe, within commercial and industrial sites, the distribution transformer is comparatively large, and supplies a very much greater load. Best regards, 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: 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 Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: Unity Power Factor
I read in !emc-pstc that Rich Nute wrote (in <200301292324.paa09...@epgc264.sdd.hp.com>) about 'Unity Power Factor' on Wed, 29 Jan 2003: >Yes, delta-wye distribution transformer overheating >does occur due to the circulation and dissipation of >the triplen harmonics in the primary (delta) winding. Thank you for that and the rest of the information, which could prove to be very helpful indeed. I would like to use it in my continuing efforts to defuse the arguments between the former TC74 experts in TC108 and the SC77A/WG1 people. May I say that the information came from you (personally, of course, not from HP)? -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Interested in professional sound reinforcement and distribution? Then go to http://www.isce.org.uk PLEASE do NOT copy news posts to me by E-MAIL! This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: Unity Power Factor
I read in !emc-pstc that Rich Nute wrote (in <200301301638.iaa15...@epgc264.sdd.hp.com>) about 'Unity Power Factor' on Thu, 30 Jan 2003: >As Ken Javor described, in the USA, voltage >distortion is largely a local (privately-owned >wiring) premises problem due to "excessive" >series resistance between the load and the >point where the utility connects to the local >premises wiring. > >Voltage distortion at the point where the utility >(public network) connects to the local premises >wiring is rare. Thank you. This is all good stuff. I wish it had been available some years ago. We've never succeeded in getting such clear and definite statements about the US experience previously. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Interested in professional sound reinforcement and distribution? Then go to http://www.isce.org.uk PLEASE do NOT copy news posts to me by E-MAIL! This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: Unity Power Factor
I read in !emc-pstc that Ken Javor wrote (in <0h9j008afer...@mtaout03.icomcast.net>) about 'Unity Power Factor' on Thu, 30 Jan 2003: >Yes I am in the US so clearly I must have been mistaken. Seriously, when >that business started in 1989 there were relatively few PCs in use there. >"PC cubes" were scattered throughout the building that people could use on >an as-needed basis. By 1995, every engineer's cube had a PC running all day >long. Yes, a similar thing happened in Europe. It was this *rapid* expansion of PC deployment that frightened the European electricity suppliers. They coped earlier with the far more gradual development of the TV park, first persuading the TV manufacturers to give up half-wave rectifiers and subsequently to control the harmonic emissions of very large sets. They extrapolated the effects of the rapid expansion of PCs (and simultaneous use of more than one TV per household) and deduced that widespread system failures would occur in a few (5?) years (counting >from about 1989) if the emissions remained controlled only by the Class A limits of IEC/EN60555-2. Hence the invention of 'Class D' and all the ensuing grief. It has now been shown pretty convincingly that the extrapolations were very pessimistic. The latest European supply industry predictions, based on voltage distortion growth levels of the past decade of 0.1% absolute per year (by 'absolute', I mean a growth from, say, 4% to 4.1% at a a particular site, not from 4% to 100.1% of 4%!), is that unacceptable levels of supply disturbance will occur in 10 years time. However, there are several reasons why that 0.1% growth rate will not be maintained over that time period, not least the effect of IEC/EN 61000-3-2 itself, which will not be reliably measurable, in Europe, until 2005 at the earliest. > It would have been interesting, in retrospect, to have taken line >voltage oscillographs at representative locations as the PC density >increased. Yes, it would have. I have about a 20 year gap in observations of the mains waveform here in UK, from about 1971 to 1991, when I heard about Class D and started to study the subject closely. During that time, the flat tops developed. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Interested in professional sound reinforcement and distribution? Then go to http://www.isce.org.uk PLEASE do NOT copy news posts to me by E-MAIL! This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: Unity Power Factor
Yes I am in the US so clearly I must have been mistaken. Seriously, when that business started in 1989 there were relatively few PCs in use there. "PC cubes" were scattered throughout the building that people could use on an as-needed basis. By 1995, every engineer's cube had a PC running all day long. It would have been interesting, in retrospect, to have taken line voltage oscillographs at representative locations as the PC density increased. >From: John Woodgate >To: emc-p...@majordomo.ieee.org >Subject: Re: Unity Power Factor >Date: Wed, Jan 29, 2003, 4:01 PM > > > I read in !emc-pstc that Ken Javor wrote > (in <0h9h00l4ovp...@mtaout02.icomcast.net>) about 'Unity Power Factor' > on Wed, 29 Jan 2003: > >>I noticed this several years ago at >>the office building I worked in at the time. My cube moved from one end of >>the building to another, and my computer wouldn't always start - it took >>several tries. I brought in a scope, and saw that the ac voltage waveform >>was flattened. It was more flattened at my new cube than at my old one. >>Clearly this is related to power supplies recharging filter caps at the peak >>of the ac waveform, and the relative distance from the building main breaker >>at the two different cubes. This is a power/crest factor issue, not >>directly a harmonic issue, although drawing current only near the peak of >>the waveform will definitely generate harmonics. > > Aren't you in the USA? If so, you must have imagined the peak- > flattening. I am assured by the US experts on SC77A/WG1 that this > phenomenon is unknown in USA, and the only effect of IEC/EN 61000-3-2 is > that it increases the prices of PCs dramatically and keeps US products > out of Europe. To which my answer is 'McEnroe!' (YCNBS!) > > At least, they argued that way for about 10 years. The present US chums > are far more sensible. Even so, 'peak flattening' rarely figures in > their vocabulary. > -- > Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk > Interested in professional sound reinforcement and distribution? Then go to > http://www.isce.org.uk > PLEASE do NOT copy news posts to me by E-MAIL! > > --- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ > > To cancel your subscription, send mail to: > majord...@ieee.org > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Ron Pickard: emc-p...@hypercom.com > Dave Heald: davehe...@attbi.com > > For policy questions, send mail to: > Richard Nute: ri...@ieee.org > Jim Bacher: j.bac...@ieee.org > > Archive is being moved, we will announce when it is back on-line. > All emc-pstc postings are archived and searchable on the web at: > http://www.ieeecommunities.org/emc-pstc > 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 Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: Unity Power Factor
Hi John: > Aren't you in the USA? If so, you must have imagined the peak- > flattening. I am assured by the US experts on SC77A/WG1 that this > phenomenon is unknown in USA, and the only effect of IEC/EN 61000-3-2 is > that it increases the prices of PCs dramatically and keeps US products > out of Europe. To which my answer is 'McEnroe!' (YCNBS!) > > At least, they argued that way for about 10 years. The present US chums > are far more sensible. Even so, 'peak flattening' rarely figures in > their vocabulary. As Ken Javor described, in the USA, voltage distortion is largely a local (privately-owned wiring) premises problem due to "excessive" series resistance between the load and the point where the utility connects to the local premises wiring. Voltage distortion at the point where the utility (public network) connects to the local premises wiring is rare. As mentioned in another message, the effect of non-linear loads (in the USA) on the utility (public) network is very low due to our use of many small distribution transformers as compared to the large distribution transformers used in Europe. The effects of non-linear loads in the USA are highly localized, and, in commercial and industrial sites, tend to be owned by the site owner. Voltage distortion on utility (public) networks in the USA tends to occur near sites of aluminum smelting and electric blast furnaces. Best regards, 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: 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 Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: Unity Power Factor
I read in !emc-pstc that Ken Javor wrote (in <0h9h00l4ovp...@mtaout02.icomcast.net>) about 'Unity Power Factor' on Wed, 29 Jan 2003: >I noticed this several years ago at >the office building I worked in at the time. My cube moved from one end of >the building to another, and my computer wouldn't always start - it took >several tries. I brought in a scope, and saw that the ac voltage waveform >was flattened. It was more flattened at my new cube than at my old one. >Clearly this is related to power supplies recharging filter caps at the peak >of the ac waveform, and the relative distance from the building main breaker >at the two different cubes. This is a power/crest factor issue, not >directly a harmonic issue, although drawing current only near the peak of >the waveform will definitely generate harmonics. Aren't you in the USA? If so, you must have imagined the peak- flattening. I am assured by the US experts on SC77A/WG1 that this phenomenon is unknown in USA, and the only effect of IEC/EN 61000-3-2 is that it increases the prices of PCs dramatically and keeps US products out of Europe. To which my answer is 'McEnroe!' (YCNBS!) At least, they argued that way for about 10 years. The present US chums are far more sensible. Even so, 'peak flattening' rarely figures in their vocabulary. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Interested in professional sound reinforcement and distribution? Then go to http://www.isce.org.uk PLEASE do NOT copy news posts to me by E-MAIL! This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: Unity Power Factor
Hi John: > >The only other problem that I know of is distribution > >transformer overheating. But, I believe such > >transformers are very much larger than 3 kVA, so 3 kVA > >of non-linear loads would have very little effect. > > > I mean *concentrations* of loads, individually below 3 kVA or so. > Distribution transformer overheating is the sort of effect that I am > interested in. Are these MV/LV transformers, 'pole-pig' types or larger. Yes, delta-wye distribution transformer overheating does occur due to the circulation and dissipation of the triplen harmonics in the primary (delta) winding. As for the type of transformer, it is the first three- phase transformer upstream from a commercial or industrial load. (In North America, these transformers are relatively small compared to Euro practice.) Such transformers are usually a part of the (larger) customer premises wiring and installation, and are not a part of the public utility distribution system. So, harmonics in commercial/industrial equipment do not appear on the public network. In North America, this overheating problem due to triplen harmonics has largely disappeared with the advent of the distribution transformer "K-factor" rating that was developed especially for this problem. By contrast, homes in North America a supplied with single-phase from a single-phase distribution transformer (which is connected across two legs of a three-phase delta supply). So, harmonics in home equipment do not appear on the public network. (Each distribution transformer supplies a maximum of 8 homes, each with 200-amp service.) In addition to overheating neutrals, some manufacturers of partitions (for office cubes -- cube sweet cube!) included three-phase wiring. The neutral connection of partition-to-partition connectors tended to overheat due to harmonics, and several fires were reported. These, too, were fixed (I believe by doubling the neutral or the neutral connection). Best regards, 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: 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 Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: Unity Power Factor
I haven't been following this thread closely, so if the following has already been addressed, I apologize. I noticed this several years ago at the office building I worked in at the time. My cube moved from one end of the building to another, and my computer wouldn't always start - it took several tries. I brought in a scope, and saw that the ac voltage waveform was flattened. It was more flattened at my new cube than at my old one. Clearly this is related to power supplies recharging filter caps at the peak of the ac waveform, and the relative distance from the building main breaker at the two different cubes. This is a power/crest factor issue, not directly a harmonic issue, although drawing current only near the peak of the waveform will definitely generate harmonics. >From: John Woodgate >To: emc-p...@majordomo.ieee.org >Subject: Re: Unity Power Factor >Date: Wed, Jan 29, 2003, 2:23 PM > > > I read in !emc-pstc that Rich Nute wrote (in > <200301291623.iaa07...@epgc264.sdd.hp.com>) about 'Unity Power Factor' > on Wed, 29 Jan 2003: >> >> >> >>Hi John: >> >> >>> >In the USA, this has largely been fixed by a change in >>> >the USA National Electrical Code. >>> >>> There must be quite a number of installations that are not yet upgraded. >> >>Where a problem existed, it was fixed by pulling >>another neutral. > > Yes, we do that, too. >> >>> Are there any other problems appearing in the field which can be >>> reliably determined as due to concentrations of non-linear loads of less >>> than 3 kVA or so? >> >>Probably not. >> >>The only other problem that I know of is distribution >>transformer overheating. But, I believe such >>transformers are very much larger than 3 kVA, so 3 kVA >>of non-linear loads would have very little effect. >> > I mean *concentrations* of loads, individually below 3 kVA or so. > Distribution transformer overheating is the sort of effect that I am > interested in. Are these MV/LV transformers, 'pole-pig' types or larger. > -- > Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk > Interested in professional sound reinforcement and distribution? Then go to > http://www.isce.org.uk > PLEASE do NOT copy news posts to me by E-MAIL! > > --- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ > > To cancel your subscription, send mail to: > majord...@ieee.org > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Ron Pickard: emc-p...@hypercom.com > Dave Heald: davehe...@attbi.com > > For policy questions, send mail to: > Richard Nute: ri...@ieee.org > Jim Bacher: j.bac...@ieee.org > > Archive is being moved, we will announce when it is back on-line. > All emc-pstc postings are archived and searchable on the web at: > http://www.ieeecommunities.org/emc-pstc > 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 Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: Unity Power Factor
I read in !emc-pstc that Rich Nute wrote (in <200301291623.iaa07...@epgc264.sdd.hp.com>) about 'Unity Power Factor' on Wed, 29 Jan 2003: > > > >Hi John: > > >> >In the USA, this has largely been fixed by a change in >> >the USA National Electrical Code. >> >> There must be quite a number of installations that are not yet upgraded. > >Where a problem existed, it was fixed by pulling >another neutral. Yes, we do that, too. > >> Are there any other problems appearing in the field which can be >> reliably determined as due to concentrations of non-linear loads of less >> than 3 kVA or so? > >Probably not. > >The only other problem that I know of is distribution >transformer overheating. But, I believe such >transformers are very much larger than 3 kVA, so 3 kVA >of non-linear loads would have very little effect. > I mean *concentrations* of loads, individually below 3 kVA or so. Distribution transformer overheating is the sort of effect that I am interested in. Are these MV/LV transformers, 'pole-pig' types or larger. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Interested in professional sound reinforcement and distribution? Then go to http://www.isce.org.uk PLEASE do NOT copy news posts to me by E-MAIL! This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: Unity Power Factor
Hi John: > >In the USA, this has largely been fixed by a change in > >the USA National Electrical Code. > > There must be quite a number of installations that are not yet upgraded. Where a problem existed, it was fixed by pulling another neutral. > Are there any other problems appearing in the field which can be > reliably determined as due to concentrations of non-linear loads of less > than 3 kVA or so? Probably not. The only other problem that I know of is distribution transformer overheating. But, I believe such transformers are very much larger than 3 kVA, so 3 kVA of non-linear loads would have very little effect. Best regards, 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: 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 Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: Unity Power Factor
I read in !emc-pstc that Rich Nute wrote (in <200301281747.jaa29...@epgc264.sdd.hp.com>) about 'Unity Power Factor' on Tue, 28 Jan 2003: > > > > >Hi John: > > >> >No, this is not much of an issue for the U.S. (unless your facility is >> >actually affecting the utility); >> >> ... or frying the neutral conductors with third-harmonic current. > >In the USA, this has largely been fixed by a change in >the USA National Electrical Code. There must be quite a number of installations that are not yet upgraded. > >When the load is largely electronic (off-line rectifiers) >the Code now requires a larger neutral conductor in three- >phase distributions. Yes, we do that in UK as well, for new installations. In some cases, the neutral, which is the same size as the phase conductors, is supplemented by another conductor, because the neutral current can, in an extreme case, exceed the phase current. > >Many constructions, while supplied from a three-phase source, >are wired as single-phase. So, in this case, the neutral >only carries the current of one phase, and we don't "fry" >the neutral. > That is a good solution. Are there any other problems appearing in the field which can be reliably determined as due to concentrations of non-linear loads of less than 3 kVA or so? -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Interested in professional sound reinforcement and distribution? Then go to http://www.isce.org.uk PLEASE do NOT copy news posts to me by E-MAIL! This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: Unity Power Factor
Hi John: > >No, this is not much of an issue for the U.S. (unless your facility is > >actually affecting the utility); > > ... or frying the neutral conductors with third-harmonic current. In the USA, this has largely been fixed by a change in the USA National Electrical Code. When the load is largely electronic (off-line rectifiers) the Code now requires a larger neutral conductor in three- phase distributions. Many constructions, while supplied from a three-phase source, are wired as single-phase. So, in this case, the neutral only carries the current of one phase, and we don't "fry" the neutral. Best regards, 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: 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: Unity Power Factor
I read in !emc-pstc that boconn...@t-yuden.com wrote (in ) about 'Unity Power Factor' on Mon, 27 Jan 2003: >No, this is not much of an issue for the U.S. (unless your facility is >actually affecting the utility); ... or frying the neutral conductors with third-harmonic current. > but I have read that the EC is currently >engaged is some interesting emission requirements discussions (Mr. Woodgate >should probably jump in...). There is nothing going on in Europe with regard to mains harmonic current emissions. IEC/EN 61000-3-2 is in effect, as it has been for a while now. There is new work going on in IEC, but don't hold your breath. The fully revised IEC 61000-3-2 is expected to be published in 2006, and if so, might become mandatory, as EN 61000-3-2, in 2010. No-one expects its technical provisions to be startlingly different from those of the current standard with the Millennium Amendment. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Interested in professional sound reinforcement and distribution? Then go to http://www.isce.org.uk PLEASE do NOT copy news posts to me by E-MAIL! This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
Re: Unity Power Factor
I read in !emc-pstc that don_macart...@selinc.com wrote (in ) about 'Unity Power Factor' on Mon, 27 Jan 2003: >Why are so many U.S. manufacturers using Unity Power Factor correctors in >low wattage power supplies? > >Are there any U.S. requirements for Harmonics or they just trying to meet >CE mark requirements (devices rated > 75W)? Well, there's IEEE519. But there's also 'hot neutrals', due to 3rd (9th, 15th...) harmonic currents adding in-phase in the neutral, which occurs in USA whereas the other European problems with harmonics don't occur so much, because the distribution system is different. Countries outside Europe are gradually adopting IEC 61000-3-2 under emission regulations. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Interested in professional sound reinforcement and distribution? Then go to http://www.isce.org.uk PLEASE do NOT copy news posts to me by E-MAIL! This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
RE: Unity Power Factor
Sir A rather large bucket of worms, these PFC and conducted emissions issues (pls see 61000-3-2). No, this is not much of an issue for the U.S. (unless your facility is actually affecting the utility); but I have read that the EC is currently engaged is some interesting emission requirements discussions (Mr. Woodgate should probably jump in...). Low-power/low-cost switchers that have PFC front-ends are common (CONFLICT OF INTEREST ALERT: MY EMPLOYER MAKES THIS STUFF); pls see http://www.t-yuden.com/powersupplies/detail_swps.cfm?ID=7 In general, manufacturers do what their customers demand. Most of our customers require PFC >0.98 at low line and rated load, so the feature becomes part of our standard "design blocks". Also, most current-generation AC/DC switching power supplies are intended to be built into stuff that can be plugged into a socket anywhere on the surface of earth, so PFC has to be part of the design. Brian -Original Message- From: don_macart...@selinc.com [ mailto:don_macart...@selinc.com] Sent: Monday, January 27, 2003 9:48 AM To: emc-p...@ieee.org Subject: Unity Power Factor Why are so many U.S. manufacturers using Unity Power Factor correctors in low wattage power supplies? Are there any U.S. requirements for Harmonics or they just trying to meet CE mark requirements (devices rated > 75W)? Regards, Don
Unity Power Factor
Why are so many U.S. manufacturers using Unity Power Factor correctors in low wattage power supplies? Are there any U.S. requirements for Harmonics or they just trying to meet CE mark requirements (devices rated > 75W)? Regards, Don 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"
