Thanks for the input from everyone. Based on the input, I have come to the opinion that pre-scans on all CPU configurations according to ANSI C63.4 should be carried out and a final scan performed on the worst case configuration of those, assuming nothing too drastically different rears its head from any of the other configurations. And testing of the AC mains(Surge, EFT/B and VD&I) and ESD can be done on a single CPU configuration. Still not 100% comfortable with this since I assume it is feasible that a surge pulse, EFT burst or e-field produced by an ESD event could somehow get to the secondary and affect the digital circuitry(CPU maybe). However, I think it is prudent to evaluate all CPU configurations to RFI, EFT/B on the I/O lines, and CI on the I/O lines. What about EN 61000-3-2 and 3-3? I don’t suspect that the various CPU’s will have any significant effect over another, so I suspect only one CPU should/could be evaluated. Any last comments? Thanks again….. Kind Regards, Sam Wismer Engineering Manager ACS, Inc. *Tel: (770) 831-8048 *Fax: (770) 831-8598 *Web: www.acstestlab.com * <******************************> swis...@acstestlab.com
From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org] On Behalf Of Peters, Michael Sent: Thursday, January 02, 2003 3:38 PM To: 'Sam Wismer'; EMC Forum Subject: RE: Multiple CPU Options Sam, It is specified in ANSI C63.4 and CISPR 22 to perform initial emissions testing to determine worst-case configuration and then to perform final emissions testing. The differences in setup can include cable arrangement, EUT/peripheral arrangement and modes of operation. Reducing the number of configurations to perform final testing would depend on the similarity of the pre-scans. If you test a particular CPU and all scans produce similar emissions results, it would make sense to determine a worst-case. If there are significant differences, it would be very difficult to determine a worst-case and all configurations should be tested thoroughly. For conducted/radiated RF, It would be necessary to test all of the different CPUs. Your client might be able to make a technical justification to perform a complete test on one clock frequency and then perform the test at that clock frequency and harmonics. I don't know if this would save test time though. I agree with John Juhasz that power-line disturbances need not be tested on each configuration. Michael Peters From: Sam Wismer [mailto:swis...@acstestlab.com] Sent: Thursday, January 02, 2003 11:23 AM To: EMC Forum Subject: Multiple CPU Options Group, Happy Holidays. Thank you for your responses to my last post concerning AC Power sources. I got a lot of good information. Next question: Client has a product that he is offering with various CPU types and speeds(5 to be exact) and is pursuing CE compliance. That is the only difference between the variants. I don't see how he can get away without testing all of them entirely since the intent of the immunity testing is evaluate the susceptibility of the product. I don't think there is room here for engineering justification of a worst case configuration. What about emissions? Is it feasible to do a pre-scan on all configurations and a final on the worst of those? I'm pretty sure what you all are going to say, but wanted to be extra certain when we present a significant quote to our customer. I would appreciate any comments as to how we can offer some cost savings measures to our client without compromising total compliance of his system. Kind Regards, Sam Wismer Engineering Manager ACS, Inc. *Tel: (770) 831-8048 *Fax: (770) 831-8598 *Web: www.acstestlab.com * <******************************> swis...@acstestlab.com
