I read in !emc-pstc that [email protected] wrote (in <[email protected]>) about 'EN 61000-3-2' on Thu, 29 Apr 2004: > For class A equipment, harmonic limits are not specified for > equipment with a rated power of 75W or less.
No, that's Class D. For Class A, the limits are expressed as currents, and apply at any 'rated power'. >What is meant by > "rated" power? Is this the power level that is actually measured > during the test or the rating as shown on the product's data plate? This was under discussion just YESTERDAY in IEC SC77A/WG1. It is intended to take action as soon as possible to remove the difficulties of interpretation associated with this term. Meanwhile, WG1, if asked, would refer to the following text in clause 6.2.2 of the standard: QUOTE The value of input power to be used for the calculation of limits shall be determined as follows: - measure the 1,5 s smoothed active input power in each DFT time window, - determine the maximum of the measured values of power from the DFT time windows over the entire duration of the test. NOTE The active input power supplied to the smoothing section of the measuring instrument as defined in annex B is the active input power in each DFT time window. The harmonic currents and the active input power shall be measured under the same test conditions but need not be measured simultaneously. The value for power, measured as defined in this clause, shall be specified by the manufacturer and documented in the test report. This value shall be used for establishing limits during emissions tests when limits are specified in terms of power. In order not to specify a power at which limits change abruptly, thus giving rise to doubt as to which limits apply, the manufacturer may specify any value which is within ± 10 % of the actual measured value. The value for power found by measurement during emission tests other than the original manufacturer's conformity assessment test, measured according to the terms of this clause, shall not be less than 90 % nor greater than 110 % of the value for power specified by the manufacturer in the test report (see 6.2.3.4). In the event that the measured value is outside of this tolerance band about the specified value, the measured power shall be used to establish the limits. ENDQUOTE -- 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 EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ieee-pses.org/ 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] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
