Re: Harmonics and conducted emissions
I read in !emc-pstc that Pettit, Ghery ghery.pet...@intel.com wrote (in 42050df556283a4d977b111eb7063208138...@orsmsx407.jf.intel.com) about 'Harmonics and conducted emissions' on Tue, 27 May 2003: EN 61000-3-2, by definition, is unhelpful. End of editorial comment. That's a bit harsh. IEC/EN 61000-3-2 expect the use of the measuring device described in IEC/EN 61000-4-7. This does not measure 'conducted emissions' in the CISPR sense. I don't see how 61000-3-2 can be 'helpful' on a subject outside its scope, but if you have a proposal I will suggest how you can get it taken into account for the planned full revision of 61000-3-2. -- 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: emc_p...@symbol.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: Harmonics and conducted emissions
Neil, The out of band emissions below 150 kHz are nothing new. I remember having this problem when testing to the old German standards that had us performing power line conducted emissions tests down to 9 kHz. The noise off the input rectifiers would saturate the front end of a spectrum analyzer, causing it to read low. A receiver with adequate pre-selection or a filter were the only options for accurate measurements. EN 61000-3-2, by definition, is unhelpful. End of editorial comment. Ghery Pettit From: Neil Helsby [mailto:nei...@solid-state-logic.com] Sent: Tuesday, May 27, 2003 3:34 AM To: emc-p...@majordomo.ieee.org Subject: Harmonics and conducted emissions Has anyone else noticed the tendency of modern switch mode power supply designers to save manufacturing costs at the expense of harmonic and conducted emissions measurements? EN 61000-3-2:2000 has introduced the concept of Partial Odd Harmonics for the 21st and above. While this adds extra functions to the spread-sheet results check, I wonder if it also has an unhelpful side effect. With conducted emissions, new power supply designs generate peak emissions at frequencies below 200 KHz that increase in level inversely to the frequency. These out-of-band emissions result in overloading the front-end of a Spectrum Analyser that consequently requires either a pre-selector or calibrated filter to function correctly. There is, of course, the alternative of purchasing a new receiver! 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: emc_p...@symbol.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: emc_p...@symbol.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: Harmonics and conducted emissions
Neil Helsby wrote: Has anyone else noticed the tendency of modern switch mode power supply designers to save manufacturing costs at the expense of harmonic and conducted emissions measurements? It's not modern. I ran into it in the 1980's. Saving costs isn't _bad_, mind; it's simply doing only what's needed to get the job done. OUR job -- among other things -- is to be sure PS designers know EMI is part of that, and help them include it at the lowest cost, too. Cortland 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: emc_p...@symbol.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: Harmonics and conducted emissions
I read in !emc-pstc that Neil Helsby nei...@solid-state-logic.com wrote (in 20030527.10334...@mis.configured.host) about 'Harmonics and conducted emissions' on Tue, 27 May 2003: Has anyone else noticed the tendency of modern switch mode power supply designers to save manufacturing costs at the expense of harmonic and conducted emissions measurements? Did you mean to write 'measurements' in that sentence? It doesn't make sense, really. EN 61000-3-2:2000 has introduced the concept of Partial Odd Harmonics for the 21st and above. While this adds extra functions to the spread-sheet results check, I wonder if it also has an unhelpful side effect. I don't see that this is necessarily relevant to the next paragraph, about conducted emissions, which are still mostly measured from 150 kHz upwards. The 'partial odd harmonics' thing deals with harmonics up to the 39th only. That's 1950 Hz in Europe and 2340 Hz in the Americas. Are you measuring conducted emissions down to 9 kHz? With conducted emissions, new power supply designs generate peak emissions at frequencies below 200 KHz that increase in level inversely to the frequency. I don't see anything 'new' in that. It applies to all SMPS, with suitable changes to the '200 kHz'. These out-of-band emissions result in overloading the front-end of a Spectrum Analyser that consequently requires either a pre-selector or calibrated filter to function correctly. There is, of course, the alternative of purchasing a new receiver! This overloading has been around for a very long time. It is one of the disadvantages of using a spectrum analyser instead of a CISPR receiver. -- 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: emc_p...@symbol.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
