So in that instance it's really verification, not calibration. Calibration always seems to imply an adjustment may be necessary. _____________________________________________________________________________________
Ralph McDiarmid | Schneider Electric | Renewable Energies Business | CANADA | Regulatory Engineer From: Ken Javor <[email protected]> To: [email protected] List-Post: [email protected] List-Post: [email protected] List-Post: [email protected] Date: 08/12/2010 01:27 PM Subject: Re: [PSES] Calibration supplier for signal generator with pulse modulation ________________________________ The LISN or CDN has to be within some tolerance of the ideal requirement in the governing standard, right? That’s it. Ken Javor Phone: (256) 650-5261 ________________________________ From: <[email protected]> List-Post: [email protected] List-Post: [email protected] List-Post: [email protected] Date: Thu, 12 Aug 2010 13:14:56 -0700 To: <[email protected]> Subject: Re: [PSES] Calibration supplier for signal generator with pulse modulation But how do you calibrate a LISN or an CDN? If there is no adjustment, then the best one can do is to 'characterize' or provide an accurate 'scale factor'. What would auditors look for other than test data compared against published numbers for the transducer? _____________________________________________________________________________________ Ralph McDiarmid | Schneider Electric | Renewable Energies Business | CANADA | Regulatory Engineer From: Deniz Demirci <[email protected]> To: [email protected] List-Post: [email protected] List-Post: [email protected] List-Post: [email protected] Date: 08/12/2010 12:55 PM Subject: Re: [PSES] Calibration supplier for signal generator with pulse modulation ________________________________ I've been performing in-house calibrations of LNA's, LISN's, CDN's, Current clamps and they have been accepted by the auditors. There is no restriction in terms of 17025 if you follow the requirements such as dedicated calibration instrumentation and MEASUREMENT UNCERTAINTY assessment. I admit my MU figure for calibration is larger than a calibration laboratory and it is accounted in EMC measurements. Again, how do you guarantee / justify what you are doing if you don't care about the MU. I am strongly disagree with the “I did it and it is correct” attitude in EMC discipline. Maybe it explains the overall situation and measurement deviations between the laboratories OOO (Own opinions only) Best regards, Deniz Demirci National Technical Systems (NTS Canada) Phone: 403-568-6605 ext 244 fax: 403-568-6970 email:[email protected] web: http://www.ntscorp.com/about/locations <http://www.ntscorp.com/about/locations> <http://www.ntscorp.com/about/locations> <http://www.ntscorp.com/about/locations> From: [email protected] on behalf of Bob Richards Sent: Thu 8/12/2010 7:51 AM To: [email protected] Subject: Re: Calibration supplier for signal generator with pulse modulation --- On Thu, 8/12/10, Ken Javor <[email protected]> wrote: And similarly, not because of MU but because of 17025 or perhaps ISO 9000, I've seen test equipment that could easily have been calibrated in house, such as current probes, LISNs and a 41 inch rod antenna have to be sent to the calibration lab. This is totally unproductive, except for the calibration lab. And I would argue further that it is detrimental to the discipline, because if you do your own calibration, you understand better how things work. This is a subject near to my heart. I've performed in-house calibrations of cables, LISNs, CDNs, current probes etc, and I agree 100% with what you said. Knowing the procedure helps to understand how things work and, just as important, gives a person the knowledge of how to perform quick verifications of a test setup in case there is ever any question as to the proper operation of that equipment. Every so often, a conversation comes up in the lab about whether we should do in-house calibrations. The issue is never about MU, cost or validity of data, it usually hinges around 17025 and what auditors will say. IMHO, shipping LISNs and/or CDNs to have calibrations performed by a cal lab is less reliable than in-house calibrations. This has little to do with the cal lab's ability, but from the possibility of damage during shipping. I've had CDNs come back with stuff rattling around inside (possibly chips off of ferrites?). If I can't perform an impedance verification in house, then what should I do to insure it is not damaged - send it back to the cal lab? Bob R. - 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 <http://www.ieeecommunities.org/emc-pstc> <http://www.ieeecommunities.org/emc-pstc> <http://www.ieeecommunities.org/emc-pstc> Graphics (in well-used formats), large files, etc. can be posted to that URL. 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