HELLO PAOLO AND DON +GROUP I agree with Don about this topic, but want to add that a printer that fails on true common mode (2 or all 3 wires to REF) and passes in a single wire configuration is on the edge of failing. I suggest, whatever the outcome of the discussion with your customer, to evaluate what happens in a larger batch then one. Possibly over 50% fails in single wire too, or better the full batch passes in true common mode. In short, this type of pass/failure dilemma asks for statistical evaluation, to make sure your decision is based on proper grounds. In addition, what happens if in the near furure an ECO changes the brand of f.a. mains filter, or even worse, the filter manufacturer changes details without announcing them. Other components may have equal impact....
Regards, Gert Gremmen, (Ing) ce-test, qualified testing =============================================== Web presence http://www.cetest.nl CE-shop http://www.cetest.nl/ce_shop.htm /-/ Compliance testing is our core business /-/ =============================================== >>-----Original Message----- >>From: [email protected] [mailto:[email protected]]On Behalf >>Of [email protected] >>Sent: Wednesday, June 07, 2000 8:44 PM >>To: [email protected]; [email protected] >>Subject: RE: EFT/Burst >> >> >> >>Paolo, >> >>EN55024 does not directly address the issue, rather it refers you to EN >>61000-4-4. Clause 7.3.1 states " . . . applied between a reference ground >>plane and each of the power supply terminals . . .". The key is "each" >>instead of "all". From a purely regulatory perspective, it >>appears you have >>a valid point the way I read the standard. Other standards do indicate >>"true common mode" as a requirement. By the way, the "reference >>ground" may >>be at a different potential than "protective earth". That's why >>a number of >>test sets have a test mode to test EFT between PE and ground reference. >>Check out the bonding and set up requirements carefully. >> >>However, a weakness in the design has been detected in "true common mode" >>test mode. Are you confident that your customer will not be >>bothered by the >>design weakness, whatever those manifestations are? Of course that is a >>quality issue, not a regulatory issue. >> >>Good luck, >> >>Don Umbdenstock >> >> >> >>> ---------- >>> From: Roncone Paolo[SMTP:[email protected]] >>> Reply To: Roncone Paolo >>> Sent: Wednesday, June 07, 2000 11:45 AM >>> To: '[email protected]' >>> Subject: EFT/Burst >>> >>> >>> Group, >>> >>> we are currently discussing with one OEM the interpretation of EFT/Burst >>> test requirements per EN55024 and EN61000-4-4 to a printer. >>> Specifically we are discussing the requirements of application of bursts >>> to >>> AC power lines. Our understanding is that they must be applied between >>> each >>> (single) power supply conductor and reference ground (or protective >>> earth), >>> as specified in EN61000-4-4 section 7.3.1. Also fig.4 and fig.11 in the >>> same >>> document seem to confirm this. >>> Our OEM customer says that all combinations of phase, neutral and >>> protective >>> earth should be tested. They actually tested both singular AC lines and >>> also >>> more than one AC line. The printer passed the test in the first mode and >>> failed in the second mode. >>> >>> Any comments / interpretations would be highly appreciated. >>> >>> Paolo Roncone >>> Compuprint s.p.a. >>> Italy >>> >>> ------------------------------------------- >>> This message is from the IEEE EMC Society Product Safety >>> Technical Committee emc-pstc discussion list. >>> >>> To cancel your subscription, send mail to: >>> [email protected] >>> with the single line: >>> unsubscribe emc-pstc >>> >>> For help, send mail to the list administrators: >>> Jim Bacher: [email protected] >>> Michael Garretson: [email protected] >>> >>> For policy questions, send mail to: >>> Richard Nute: [email protected] >>> >>> >> >>------------------------------------------- >>This message is from the IEEE EMC Society Product Safety >>Technical Committee emc-pstc discussion list. >> >>To cancel your subscription, send mail to: >> [email protected] >>with the single line: >> unsubscribe emc-pstc >> >>For help, send mail to the list administrators: >> Jim Bacher: [email protected] >> Michael Garretson: [email protected] >> >>For policy questions, send mail to: >> Richard Nute: [email protected] >> >>
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