What type of product are you classifying this as? PC's and a graphics controller could be considered ITE. No matter, class D is limited to either PC's, displays, and TVs (using A14) or special input current wave shapes (without A14). In either case, you will end up with a class A product. I thought that since you are using PC's, you might have forced yourself into Class D.
The problem with class A limits is that the higher your power draw, the lower your relative limits are. As you get between 600 and 1000W, class D limits can be higher than class A limits in which you might pass (depending on how bad you were failing). What is the total power consumption of this product? There are no limits for professional use equipment over 1000W. If you are under 1KW, why are you using 3 phase power? Regards, Glenn Lesmeister Product Regulatory Compliance The New HP Tel: 281-514-5163 20555 SH 249, MS60607 Fax: 281-514-8029 Houston, TX 77070-2698 Pgr: 713-786-4930 glenn.lesmeis...@hp.com -----Original Message----- From: rbus...@es.com [mailto:rbus...@es.com] Sent: Thursday, February 20, 2003 4:37 PM To: Lesmeister, Glenn; emc-p...@ieee.org Subject: RE: Harmonics Testing for PCs The PDU (power distribution network) provides 4-5 outlets per phase. We try to balance based on current loads rather than qty of cords. The graphics processor draws significantly more current per cord than the PCs. As for the limits, we are using A. I understand that D is used exclusively for ITE and has tighter limits. From: Lesmeister, Glenn [mailto:glenn.lesmeis...@hp.com] Sent: Thursday, February 20, 2003 3:23 PM To: Rick Busche; emc-p...@ieee.org Subject: RE: Harmonics Testing for PCs Rick, You don't indicate how all of the other components are wired in the power distribution system. If you are balancing all load on the 3 phases, but only have 2 cords for the graphics controller, you must have something else picking up the slack on the 3rd phase. Are there any other combinations you could try? Just out of curiosity, what limits are you applying to this system (A or D)? Regards, Glenn Lesmeister Product Regulatory Compliance The New HP Tel: 281-514-5163 20555 SH 249, MS60607 Fax: 281-514-8029 Houston, TX 77070-2698 Pgr: 713-786-4930 glenn.lesmeis...@hp.com -----Original Message----- From: rbus...@es.com [mailto:rbus...@es.com] Sent: Thursday, February 20, 2003 2:59 PM To: emc-p...@ieee.org Subject: Harmonics Testing for PCs Recently I had the opportunity to test one of our latest products, which has essentially 6 rack mounted PCs and a custom designed graphics processor. The graphics processor has two internal (identical) power supplies on separate power cords but with a shared output current. The purpose of the dual cord is to balance the input current across the three phases. All power supplies are PFC. The system is three phase with all cords connected phase to natural (120V or 230V) by way of a power distribution system. During the Harmonics test (EN 61000-3-2) the system failed harmonics. Testing all of the peripherals individually, they all passed. As a system, the only way it would pass is to have both power cords from the graphics processor plugged into a single phase. Obviously this compromises our ability to balance the input current as well as we would have liked. So my question to the group is: 1. Why would the arrangement of the power cords affect the harmonic noise. My guess might be a defective power controller but beyond that I am perplexed. On a similar note, another similar system was tested to EFT and Surge per EN 61000-4-4 and EN 61000-4-5. During the testing one of the six power supplies popped at 500V. It sounded a lot like an MOV exploding. Contacting the manufacturer he provided me extensive test data and an assurance that the supplies are designed to pass the test. I am now in the process of re-testing. My question is: 2. What is the effect of EFT or Surge on a system as opposed to a individual chassis or p/s. It seems to me that the more power supplies on a given input, the greater the chance that the energy would be absorbed and the system passing. Thanks Rick Busche Evans & Sutherland rbus...@es.com 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 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 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 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
