Rich:
Yet another complication arises when you bring MIL-STD-220 into the picture. This standard provides a means of characterizing the performance of line filters, but does so using a 50-Ohm system impedance. While this makes for convenient measurements, it gives you only a guess about how the filter works in real life, where the source and load impedances are typically not anywhere near 50 Ohms. Ed Price [email protected] <blocked::mailto:[email protected]> WB6WSN NARTE Certified EMC Engineer Electromagnetic Compatibility Lab Cubic Defense Applications San Diego, CA USA 858-505-2780 Military & Avionics EMC Is Our Specialty From: [email protected] [mailto:[email protected]] On Behalf Of Jones, Richard (Richard) Sent: Friday, September 10, 2010 1:12 PM To: [email protected] Subject: RE: [PSES] Power Line Filters for EMC Chambers This is interesting, I had interpreted it to mean that I was checking to ensure no RF was getting out of the chamber rather than getting in. I guess it’s fairly safe to say if I don’t measure anything inside probably nothing is getting out either! The question actually came out of ISO 17025 where it states: 150-11 5.5.1 b) Requirements for checking associated critical equipment, such as power line filters, and grounding systems shall also be specified and the results documented. I was thinking along the lines of 100dB performance and taking actual measurements, which after looking at Mil Std 220 and CISPR17 isn’t for the faint hearted! Rich From: Price, Edward [mailto:[email protected]] Sent: Friday, September 10, 2010 3:35 PM To: [email protected] Subject: Re: [PSES] Power Line Filters for EMC Chambers Rich: If you mean testing the RF filtering performance of the filters, you could just use a very empirical approach. After all, what are the filters supposed to do? Answer, keep RF noise out of the chamber. If you periodically do a conducted and radiated emission ambient check inside the chamber, and, if you don’t detect any emissions, then the filters are working. Ed Price [email protected] <blocked::mailto:[email protected]> WB6WSN NARTE Certified EMC Engineer Electromagnetic Compatibility Lab Cubic Defense Applications San Diego, CA USA 858-505-2780 Military & Avionics EMC Is Our Specialty From: [email protected] [mailto:[email protected]] On Behalf Of Jones, Richard (Richard) Sent: Friday, September 10, 2010 9:35 AM To: [email protected] Subject: RE: [PSES] Power Line Filters for EMC Chanmbers For EMC labs: Does anyone have a method for testing Power Line Filter performance once installed on an EMC Chamber. I was asked this question recently as our filters are over 10yrs old, at the time I couldn’t think of anything short of removing them to test performance. I did wonder if some simple verification of filter current leakage to ground would suffice as capacitors age but the inductors less so, ofcourse that’s not checking actual performance. The installation is visually checked and grounding measured regularly and up until now no other thought was given to it. Rich - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher <[email protected]> David Heald <[email protected]> - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher <[email protected]> David Heald <[email protected]> - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher <[email protected]> David Heald <[email protected]>
