Hello Group, Thanks for all that answered my question. This question was due to some measurements of conducted emissions that i've made. First, i've done measurements with the Ground Choke in position "OUT". Then, the ambient interference diminished a lot, as shows Fig. 1. Then i've switched the ground choke to "IN" position, as shows Fig. 2. The standards i'm using are based on European Standards ( CISPR 22, CISPR 15). Figs. 1 and 2 are attached.
So, when i try to do measurements, the spectra of conducted emissions change according to switch position (ground choke on or off). My questions are: => Which emission measurement should i trust: the one with switch "IN" or the one in "OUT" position (ground choke "in" or "out") => Could somebody make clear to me if CISPR requires this ground choke? => the ground choke is a must only in VDE measurements? I Think that's all... Thanks in advance! Muriel Helge Knudsen wrote: > > Dear group, > The use of ground choke in conducted measurements was specified in > "Verfügerung 1046/1982" when testing to comply with VDE 0871 if the > measured noise was closer to the limit than 5 dB. > This second measurement must then also comply with the limit. > The value of this ground conductor choke was specified to 1.6 mH. > > I believe the reason for this sophisticated measurement were required > because the inductance in ground lead in really live may increase the noise > level with several dB's. > I hope this clarified the matter. > > Best regards > Helge Knudsen > Jyske EMC > Denmark > hknud...@jyske-emc.com > > -----Original Message----- > From: Cortland Richmond [SMTP:72146....@compuserve.com] > Sent: lørdag, december 05, 1998 05:43 > To: Gary McInturff; ieee pstc list > Subject: RE: Doubt on LISN utilization > > As I recall, when testing conducted emissions to VDE 0871, it was required > to observe noise in the two powered lines with the switch both open and > closed, and use the higher result. Some power supplies would in fact give > different results if the ground was opened. > > An aside: I used to work at Tandy Computer's R&D. When Tandy quit making > computers (and I was laid off), I was able to buy a Rhode and Schwarz LISN > they scrapped -- for $25. It has the ground switch Muriel describes. When > I bought it for Tandy, it cost much, much more! > > Cortland > > --------- > This message is coming from the emc-pstc discussion list. > To cancel your subscription, send mail to majord...@ieee.org > with the single line: "unsubscribe emc-pstc" (without the > quotes). For help, send mail to ed.pr...@cubic.com, > j...@gwmail.monarch.com, ri...@sdd.hp.com, or > roger.volgst...@compaq.com (the list administrators). > --------- > This message is coming from the emc-pstc discussion list. > To cancel your subscription, send mail to majord...@ieee.org > with the single line: "unsubscribe emc-pstc" (without the > quotes). For help, send mail to ed.pr...@cubic.com, > j...@gwmail.monarch.com, ri...@sdd.hp.com, or > roger.volgst...@compaq.com (the list administrators). -- ================================================== Muriel Bittencourt de Liz INEP - Instituto de Eletronica de Potencia Universidade Federal de Santa Catarina Caixa Postal - 5119 88.040-970 - Florianopolis - SC - BRASIL Phone: +55.48.331.9204 - Fax: +55.48.234.5422 e-mail: mur...@inep.ufsc.br Homepage: http://www.inep.ufsc.br ==================================================
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