In article <[email protected]. com>, Gary McInturff <[email protected]> writes
> We have a new project that is, for all practical purposes a custom > design for a client. > We purchase a supply that indicates compliance with EN61000-3-2 > harmonics. Our customer wants a more quantitative number. Is it 90% > PFC, 95% etc. You don't have '90% PFC' power factor correction), you have '90% PF' (power factor). Next, power factor, defined as true power/apparent power, is composite if the load is non-linear. There is a 'displacement power factor', which, if the voltage wave form OR the current waveform is substantially undistorted is simply the cosine of the phase angle between the sinusoidal quantity and the fundamental component of the non-sinusoidal quantity. If both voltage and current are non-sinusoidal, then both the true power and the apparent power contain terms associated with harmonic frequencies. Then there is the 'distortion power factor', which is a measure of the ratio of total r.m.s. voltage to its fundamental component and of the total r.m.s current to its fundamental component. > I can't tell that from the spec sheet and quite frankly at this > point I can't lay my hands on a power supply yet and obviously we > haven't gone to test yet with this in our equipment so I don't > believe I have any way of determining this (not sur > e that I could > tell from the conformance test anyway - can I?) Yes, if you get the raw data (amplitude of every component of supply voltage and input current, with their phase angles) and process it. > When I call the power supply manufacturer, I can't directly > address the design engineer and all they can tell me is that it > meets the requirements for Class A waveform. > Am I overlooking something here in the datasheet? Is there > anyway to infer what what the PFC % is? If it only meets the Class A limits, it doesn't have much distortion power factor correction, if any. The displacement power factor depends on how heavily the power supply is loaded. You aren't going to solve this without getting your hands on an actual power supply. Believe me! -- 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 Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Ron Pickard: [email protected] Scott Douglas [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
