Mr. Wismer, all, > 2. As for FCC if the vendor claims of EMC Directive compliance includes > conforming with harmonized emission standards like En 55022, then I think > this could be OK. I would recommend you have a preliminary scan taken at a > test lab however. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^
I would strongly recommend re-testing for EMI. While your results for line-conducted emissions (LCE: 150 KHz- 30 MHz) should compare well to the OEM's, there are a lot of things that can go wrong with radiated emissions (30 MHz - 1000 MHz+) and even with higher LCE frequencies. Some pitfalls: 1. If the OEM tested with a power supply chassis but your application is open-frame, 2. If the location of your AC inlet and/or AC line filter is less ideal than the OEM's was during their testing, 3. If the power supply Earthing to the system chassis has a higher impedance than the OEM's was during their testing, 4. Since the OEM's PC will generate different radiated frequencies than your system, you may have different emissions radiating from your power cord, some even failing. 5. The fusing circuit you intend to add will only make radiated emissions from your power cord worse, because emissions from your system may capacitively-couple to your AC wiring (depending on 1-3 above.) Also, for LCE, it is important that the OEM test at low line (100 VAC?) high line (240 VAC?) full load, and minimum load. I have found that low line, full load is usually worst-case for typical foward-converter switching power supplies. As the system integrator, you are not required to test at full load unless your system can use all the available output power. (Power harmonics testing is specified at 230 VAC, full load, however.) Any good EMI test lab will be well-versed in good power supply integration for EMC, and also in countermeasures for failing emissions. Good Luck, Dan > From [email protected] Wed Aug 12 21:15:29 1998 > From: "rlanz" <[email protected]> > To: <[email protected]> > Subject: Re: Who's responsibility..... > Date: Wed, 12 Aug 1998 17:52:14 -0400 > X-MSMail-Priority: Normal > X-Priority: 3 > MIME-Version: 1.0 > Content-Transfer-Encoding: 7bit > X-Resent-To: Multiple Recipients <[email protected]> > X-Listname: emc-pstc > X-Info: Help requests to [email protected] > X-Info: [Un]Subscribe requests to [email protected] > X-Moderator-Address: [email protected] > > > 1, If your objective is to obtain NRTL certification on your system, I > would not purchase a supply unless it was UL listed or recognized. The UL > mark would be accepted by any NRTL you submit your system to. Otherwise > you would have to be responsible for the safety compliance of the supply, a > nearly impossible task. > > 2. As for FCC if the vendor claims of EMC Directive compliance includes > conforming with harmonized emission standards like En 55022, then I think > this could be OK. I would recommend you have a preliminary scan taken at a > test lab however. Also the vendor should provide you with his Declaration > of Conformity listing the evaluation standards. > > Regards > Rich Lanzillotto > [email protected] > Regulatory Consultant > ---------- > > From: Wismer, Ronald S. <[email protected]> > > To: 'EMC Forum' <[email protected]> > > Subject: Who's responsibility..... > > Date: Tuesday, August 11, 1998 11:20 AM > > > > Our company(In the US) wishes to purchase an AC/DC power supply from > > an outside vendor(From overseas). We then, plan to add some fusing > > circuitry, an enclosure, and a terminal block so that it mechanically > > meets our needs. The vendor claims to meet the EMC and LV directives, > > but no claims to FCC approval. Our market of interest is the US only, > > thus the problem. > > > > My question is, if the vendor can not produce proof that that they > > tested to, and comply with, the FCC requirements, is it allowable for > > our company to qualify the device and label it accordingly? Are there > > any risks involved in doing so? > > > > I appreciate any comments. > > > > Sam Wismer > > LXE, Inc. > > > > --------- > > This message is coming from the emc-pstc discussion list. > > To cancel your subscription, send mail to [email protected] > > with the single line: "unsubscribe emc-pstc" (without the > > quotes). For help, send mail to [email protected], > > [email protected], or [email protected] (the list > > administrators). > > > > --------- > This message is coming from the emc-pstc discussion list. > To cancel your subscription, send mail to [email protected] > with the single line: "unsubscribe emc-pstc" (without the > quotes). For help, send mail to [email protected], > [email protected], or [email protected] (the list > administrators). > > --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to [email protected] with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to [email protected], [email protected], or [email protected] (the list administrators).
