I read in !emc-pstc that don_borow...@selinc.com wrote (in <ofae2c2f5d.695d080d-on88256cbc.00568...@selinc.com>) about 'Applicabilty of Flicker Standard' on Tue, 28 Jan 2003: > >We are trying to figure out the applicability of 61000-3-3 Flicker Standard >to the power supply in our product. We have a device that may be "hard >wired" into the public low voltage (230 V) mains under certain >circumstances, and has no mains switch. Given this, it appears that the >maximum relative voltage change dmax shall not exceed 4% (61000-3-3, >Section 5, Limits, condition a.) since it is "energized immediately on >restoration of supply after a power supply interruption". > >Question 1: Does the 4% dmax include the inrush upon restoration of supply, >or does it apply only to voltage changes caused by changes in current >demand during operation (after inrush)?
It includes the inrush current. The standard is NOT only about flicker; this impression is due to the less-than-generalized title. It is about all sorts of **voltage changes** impressed on to the supply by loads. See the Amendment for better information on inrush current. > >To make things even messier, the device in question is a control for a >power distribution recloser (over 1 kV). During a fault, it might demand >enough current to exceed 4% dmax when operating the recloser. The public >low voltage powering the control would almost certainly be derived from the >high voltage system being switched by the recloser. > >Question 2: Do we need to meet the 61000-3-3 limits during recloser >operation (most likely fault conditions)? > Probably not if it is installed within a utility's site. AIUI, any low- voltage supply there is not a 'public' supply. If it can be installed in a user's premises, then the low-voltage supply might not be derived from the MV supply being switched (in a big hospital, for example, which has two separate HV or MV supplies for reliability). In that case, the standard applies. -- 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"
