Thanks for your comments. What if you could not load the product to get to the rated input current?
For example, the power supply goes into fold back before the actual input current reaches what is printed on the name plate label? Is this an indirect way of limiting the over kill one can use when assigning an input rating? Not everyone uses an electrical rating that is dead on to what the product actually draws. Glenn -----Original Message----- From: [email protected] [SMTP:[email protected]] Sent: Thursday, October 09, 1997 10:33 AM To: Lesmeister, Glenn; [email protected] Subject: Re: Application of EN61000-3-2 On Tue, 7 Oct 1997 16:45:26 -0500, you wrote: >Rich, >I'm a little confused by one of your points. You said "...PCs be >loaded, artificially if necessary, to the point where the input >current is the maximum rated current at the nominal rated voltage". > >Are you saying that if I rate my PC 100-240Vac, 6A max, I must load it >to 6A? What if the power supply is only 100W and can only be loaded >to an amp or so at 240V? Sad, but true. Excerpt from IEC1000-3-2:1995-03, Annex C - Type test conditions C.10 Test conditions for information technology equipment (ITE) "ITE is tested with the equipment configured to its rated current. In this case, the equipment, if necessary, may be configured with its power supplies loaded with additional load (resistive) boards to simulate rated current conditions." As for a single load current rating: can you call out separate load currents at different nominal voltages? ie, 115VAC/6A, 230VAC/3A. >I would think that a max DC load should be specified by the >manufacturer and used for this test (as well as input and heating). > >Glenn >-----Original Message----- >From: Rich Nute [SMTP:[email protected]] >Sent: Monday, October 06, 1997 4:11 PM >To: [email protected] >Cc: [email protected]; [email protected] >Subject: Re: Application of EN61000-3-2 > > > >Hello from San Diego (y buenas dias de San Diego): > > >The intent of the EN 61000-3-2 requirement to measure at rated >current is just that: rated current. > >The objective of EN 61000-3-2 is to minimize the effects of >harmonic current on the public network. To this end, the worst- >case harmonic current emissions is when the load is operating >at maximum current. Hence, the requirement that testing be >performed at rated current. > >For rectifier-capacitor loads such as linear or switching >electronic power supplies, worst-case harmonic emissions occurs >at maximum dc load at the output of the power supply. > >It was the intent of the authors of IEC 1000-3-2 that products >such as PCs be loaded, artificially if necessary, to the point >where the input current is the maximum rated current at the >nominal rated voltage. > >When I measure a product for harmonic current emissions, I measure >the power supply by itself with an electronic load set such that >the input current is the maximum rated input current. > >In practice, one need not measure harmonic currents. If the power >supply is a linear or switcher rated more than 75 watts, then it >fails -- unless it is a switcher with a PFC front-end. If it is >less than 75 watts, then it is acceptable. (Even though there are >limits for 75 watts and less, the limits are so high that it is >not possible for the emissions to exceed the limits.) > >(I grant that there may be some exceptions to the above rules- >of-thumb, but they are relatively rare and unusual.) > >For example, we have a 220-watt power supply operating in an >application where the maximum rated input is less than 75 watts. >Therefore, it does not need a PFC front-end. (The power supply >is common to other products which are sold outside the EU and >do not need the PFC.) > >Best regards (y saludos), >Rich > >------------------------------------------------------------- > Richard Nute Quality Department > Hewlett-Packard Company Product Regulations Group > San Diego Division (SDD) Tel : 619 655 3329 > 16399 West Bernardo Drive FAX : 619 655 4979 > San Diego, California 92127 e-mail: [email protected] >------------------------------------------------------------- -- Patrick Lawler [email protected]
