CONFLICT OF INTEREST ALERT: My employer makes SMPS. For both conducted emissions, an unit with PFC typically makes life easier. For reduced radiated emissions, avoid the open "U" chassis units. Please note that as customers demand greater efficiencies and reduced sizes, you will see much higher main converter frequencies.
In any case, a supplier that (assuming your test technique is consistent) produces units with a wide variance in emissions characteristics may be indicative of poor design and/or no quality control. Brian -----Original Message----- From: Jim Conrad [mailto:jc...@shore.net] Sent: Tuesday, September 03, 2002 3:55 AM To: Alex McNeil; emc-p...@majordomo.ieee.org Subject: RE: SMPS EMC Emissions Alex wrote: "Do you think it is reasonable to specify in my power supply specification that the manufacturers SMPS should meet EN55022 Class B -6dB" Yes. I would ask for 6 dB margin since measurement uncertainty for a typical conducted measurements system is 5.4 dB. You must also allow for unit to unit variations in manufacturing. Sample 5 units and apply the 80/80 rule and see if they still pass. Jim -----Original Message----- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Alex McNeil Sent: Tuesday, September 03, 2002 4:57 AM To: 'emc-p...@majordomo.ieee.org' Subject: SMPS EMC Emissions Hi Group, First of all thank you to those who replied to my previous email. I have not had time to reply personally...yet. I have noticed that the broadband noise of some SMPS are already near to the limits of EN55022 Class B (I tested with a max resistive load). This gives my product little scope for emissions at these broadband frequencies, especialy when my product is taking peak load e.g. printing. The power supply manufacturer rightly claims that his product does meet EN55022 Class B. Do you think it is reasonable to specify in my power supply specification that the manufacturers SMPS should meet EN55022 Class B -6dB or....? Have any of you come across a similar scenario? As usual , I look forward to your professional opinions. Kind Regards Alex McNeil Principal Engineer Tel: +44 (0)131 479 8375 Fax: +44 (0)131 479 8321 email: alex.mcn...@ingenicofortronic.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"
