I read in !emc-pstc that jules <[email protected]> wrote (in <2B924D0A9291D511B59300D0B7208EA808DE75@HEMC01>) about 'flicker results with PWM circuits' on Tue, 18 Feb 2003:
> we have a customer designing and manufacturing Pulse Width Modulation >power controllers. These are used in the heating & ventilation industry , >within factories and hotels etc. due to the nature of the design switching >full power on and off between 2 and 30 times a minute it fails flicker >EN61000-3-3. Looking at the std and doing the maths on a 2kw load, it needs >to be switching only once a minute to meet flicker requirements. Problem >with this is only switching once a minute the control is lost ! This is precisely what IEC 61000-3-11 is for, even for products below 16 A. Note that the title doesn't specify 16 A as the lower limit. The manufacturer has to specify the maximum supply impedance for which the product meets the flicker requirements, i.e. the limits in IEC 61000-3-3 (including the large Amendment, of course). -- 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: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] 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
