Re: Power Factor correction
In article f7e9180f6f7f5840858d3db815e4f7ad05fb9...@cms21.t-yuden.com, Brian O'Connell boconn...@t-yuden.com writes Typically, I have always measured/calculated distortion PF using the current waveform. What market segments tend to use/prefer the voltage w/f ? Do you think that end-users of component power supplies prefer one parametric over the other ? I tried to keep the explanation brief, but obviously it was too brief. In general, both the voltage and the current are distorted, and in-phase components of the voltage and current harmonics add to the true power. Equally, quadrature components add to the apparent power. If you just assume that the voltage is sinusoidal when it isn't, you do not get the right answers. If it only meets the Class A limits, it doesn't have much distortion power factor correction, if any. The displacement power factor depends on how heavily the power supply is loaded. I would appreciate if you could offer more commentary/insight on this statement. Perhaps this is not based on power supplies that use active PFC, where output loading has minimal influence on measured PF within the unit's ratings. It isn't based on power supplies with active PFC. But such supplies normally meet the Class D limits if under 600 W active input power, so I inferred from the citing of Class A limits that your power supply didn't have active PFC. If it does, the power factor is likely to be very high, and not a matter of concern for your customer. But it would be unwise to guess a figure. -- Regards, John Woodgate, OOO - Own Opinions Only. The good news is that nothing is compulsory. The bad news is that everything is prohibited. http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list.Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.org Instructions: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Scott Douglas emcp...@ptcnh.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: http://www.ieeecommunities.org/emc-pstc
RE: Power Factor correction
-Original Message- From: John Woodgate [ mailto:j...@jmwa.demon.co.uk] Sent: Saturday, October 16, 2004 2:03 PM To: emc-p...@ieee.org Subject: Re: Power Factor correction Then there is the 'distortion power factor', which is a measure of the ratio of total r.m.s. voltage to its fundamental component and of the total r.m.s current to its fundamental component. Typically, I have always measured/calculated distortion PF using the current waveform. What market segments tend to use/prefer the voltage w/f ? Do you think that end-users of component power supplies prefer one parametric over the other ? If it only meets the Class A limits, it doesn't have much distortion power factor correction, if any. The displacement power factor depends on how heavily the power supply is loaded. I would appreciate if you could offer more commentary/insight on this statement. Perhaps this is not based on power supplies that use active PFC, where output loading has minimal influence on measured PF within the unit's ratings. You aren't going to solve this without getting your hands on an actual power supply. Believe me! All should heed this statment from a man older and wiser then me... Nothing beats empirical verification, under end-use conditions. luck, Brian This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.org Instructions: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Scott Douglas emcp...@ptcnh.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: http://www.ieeecommunities.org/emc-pstc
Re: Power Factor correction
In article 9F347458EDACB64B8FF57DB67E6E0FAA0121E14D@cerebrum.spraycool. com, Gary McInturff gmcintu...@spraycool.com writes We have a new project that is, for all practical purposes a custom design for a client. We purchase a supply that indicates compliance with EN61000-3-2 harmonics. Our customer wants a more quantitative number. Is it 90% PFC, 95% etc. You don't have '90% PFC' power factor correction), you have '90% PF' (power factor). Next, power factor, defined as true power/apparent power, is composite if the load is non-linear. There is a 'displacement power factor', which, if the voltage wave form OR the current waveform is substantially undistorted is simply the cosine of the phase angle between the sinusoidal quantity and the fundamental component of the non-sinusoidal quantity. If both voltage and current are non-sinusoidal, then both the true power and the apparent power contain terms associated with harmonic frequencies. Then there is the 'distortion power factor', which is a measure of the ratio of total r.m.s. voltage to its fundamental component and of the total r.m.s current to its fundamental component. I can't tell that from the spec sheet and quite frankly at this point I can't lay my hands on a power supply yet and obviously we haven't gone to test yet with this in our equipment so I don't believe I have any way of determining this (not sur e that I could tell from the conformance test anyway - can I?) Yes, if you get the raw data (amplitude of every component of supply voltage and input current, with their phase angles) and process it. When I call the power supply manufacturer, I can't directly address the design engineer and all they can tell me is that it meets the requirements for Class A waveform. Am I overlooking something here in the datasheet? Is there anyway to infer what what the PFC % is? If it only meets the Class A limits, it doesn't have much distortion power factor correction, if any. The displacement power factor depends on how heavily the power supply is loaded. You aren't going to solve this without getting your hands on an actual power supply. Believe me! -- Regards, John Woodgate, OOO - Own Opinions Only. The good news is that nothing is compulsory. The bad news is that everything is prohibited. http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list.Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.org Instructions: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Scott Douglas emcp...@ptcnh.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: http://www.ieeecommunities.org/emc-pstc
RE: Power Factor correction
To calc PF you would need to know the true power and apparent power at a particular test configuration. PF for an unit with active (more expensive) PFC should vary very little over the rated input range. PF for units with passive (less expensive) PFC will probably vary several percent over the rated input and output ranges. PF for unit with no PFC (cheap) vary significantly with changes in line quality, and significantly over the rated input and output ranges. No free lunch... It is important to measure PF with an instrument intended for the measurement. There are many ways to measure PF using just scopes and/or meters, but unless you have instruments with very high crest factors, that can make phase-relative measurements, and can accurately integrate over many cycles, your resultant number could be suspect. Final caveat, I have tested component power supplies from various sources. And I have noted a few atypical cases where a unit reliably maintained a consistent and high PF, but was operating at the limits or failing (depending on the Class) according to CISPRs and the 61000-3-2 conducted immunity test. luck, Brian -Original Message- From: robert Macy [ mailto:m...@california.com] Sent: Monday, October 11, 2004 4:16 PM To: Gary McInturff; emc-p...@ieee.org Subject: Re: Power Factor correction Gary, Is it possible to calculate the pfc from the spec? - Robert - On Mon, 11 Oct 2004 10:54:01 -0700 Gary McInturff gmcintu...@spraycool.com wrote: Ladies and Gentlemen I think I may be stuck between a rock and a hard place. We have a new project that is, for all practical purposes a custom design for a client. We purchase a supply that indicates compliance with EN61000-3-2 harmonics. Our customer wants a more quantitative number. Is it 90% PFC, 95% etc. I can't tell that from the spec sheet and quite frankly at this point I can't lay my hands on a power supply yet and obviously we haven't gone to test yet with this in our equipment so I don't believe I have any way of determining this (not sure that I could tell from the conformance test anyway - can I?) When I call the power supply manufacturer, I can't directly address the design engineer and all they can tell me is that it meets the requirements for Class A waveform. Am I overlooking something here in the datasheet? Is there anyway to infer what what the PFC % is? Gary This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.org Instructions: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Scott Douglas emcp...@ptcnh.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: http://www.ieeecommunities.org/emc-pstc
Re: Power Factor Correction
I read in !emc-pstc that Dave Spencer dspen...@dsl-only.net wrote (in 185530-22003324161424...@dsl-only.net) about 'Power Factor Correction' on Tue, 4 Mar 2003: I am looking for some input on your experience with PFC as it relates to testing (EN61000-3-2 and EN55022). Has anyone using an AC-AC external transformer in the 15-20 Watt range experienced difficulty passing, e.g. no PFC? Well, you don't say what the transformer is feeding! Assuming it's a bridge rectifier with a fat filter capacitor, the resistances of the transformer windings are usually sufficient to make the rectifier conduction angle exceed 65 degrees, which should be sufficient to meet the Class D limits. BUT those limits doesn't apply below 75 W anyway! One might guess that you haven't read the standard, and have thus been worrying over a non-problem. OTOH, one might, of course, be wrong in an entirely unexpected direction. -- 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: Power Factor Correction - Power supply unit
I read in !emc-pstc that am...@westin-emission.no wrote (in LFENJLPMMJB mhpeibnilieihccaa.am...@westin-emission.no) about 'Power Factor Correction - Power supply unit', on Thu, 31 Jan 2002: Hi all, An AC/DC power supply (230AC in / 28VDC 3A out) shall power an ITE (fire alarm panel). I assume that EN61000-3-2 will apply for the total system (Power supply + ITE). Yes. I was told that the power supply must have Power Factor Correction in order to pass the harmonic EN61000-3-2 test. Not necessarily. The ***Class A*** limits apply, not the Class D. This is possibly the most significant change introduced by the Millennium Amendment (A14). Class D applies now to PCs, VDUs and TV sets, not to all ITE. I think it is unlikely that a 100 W power supply can violate the Class A limits. If it isn't a switch-mode type (i.e. it has a mains transformer) it may even meet the Class D limits, or could be modified at low cost to do so. -- 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: Power Factor Correction, Medical Equipment?
Although you are correct - neither does the EMC Directive. BUT the EN for harmonics IS in the OJ and it would seem to me to be applicable. Any one else agree??
Re: Power factor Correction
The power factor correction standard is IEC 1000-3-2 (aka EN 61000-3-2). This standard applies to ALL electrical and electronic products exceeding 75 watts maximum rated power. The EN standard applies to all countries of the European Community (most of Western Europe). EN 61000-3-2 falls under the EMC Directive. The EMC Directive is effective 01 January 1996. Therefore, EN 61000-3-2 is effective 01 January 1996. EN 61000-3-2 replaces EN 60555-2 (aka IEC 555-2). EN 60555-2 applies to home appliances. For products currently under EN 60555-2, the Date of Withdrawal (DOW) of EN 60555-2 is 01 January 1997. Therefore, EN 61000-3-2 is effective for home appliances 01 January 1997. An interpretation is that because EN 60555-2 excludes all other equipment, the DOW is also the effective date for all equipment excluded from EN 60555-2. Therefore, the effective date of EN 61000-3-2 for ALL equipment is 01 January 1997. From discussions in this forum, it appears that some authorities in some countries (e.g., the U.K.) are accepting this interpretation, while other authorities and other countries are silent. The conservative approach (i.e., without risk) for non-home appliance products is that such products comply with EN 61000-3-2 as of 01 January 1996. The risky approach is to delay incorporation of power factor correction until 01 January 1997. The risky approach relies on an interpretation, which varies among authorities and countries. If an authority or country holds the conservative position, then the risk is that of being caught claiming compliance with the EMC Directive, yet not including EN 61000-3-2 in the Manufacturer's Declaration. The risk is having products denied entry into the country, and recall for those products already within the country. Clearly, the folks responsible for EN 61000-3-2 have created a very difficult position for manufacturers, one without sufficient notice for implementation, and one with confusing effective dates. If you have followed the development of IEC 1000-3-2, you will have seen the rather dictatorial style of the committee leaders and lack of consideration for other viewpoints. Furthermore, it is clear that they have not provided leadership in providing adequate public announcement that the standard becomes effective with the EMC Directive. We've had years to prepare for the EMC Directive, but only about one year to prepare for EN 61000-3-2. Best regards, Rich
