Mr. Robinson, Nothing said necessarily represents the opinions or policies of my employer(s).
Agree with Doug Powell's comments. Methinks this is a bit more of an internal policy for the NCB/NRTL than what has been specified by regulation or standards. The conformity assessment bodies where my employers have been subject to an 'agency client data' program all have evaluated the company lab's test equipment, associated calibration program, and the lab's measurement uncertainty calculations. All of my lab accreditations indicated each particular test where data can be accepted, described the authorized test equipment, and listed the authorized signatories for the TRF; but only three of the five accreditations of my employers' labs indicated the uncertainty for each type of measurement. Some NRTLs do measurement uncertainty via an "Calibration Certificate Analysis", where the calibration people must provide uncertainty on the issued cal cert. Repeatability of component temperature measurements for power supplies, is difficult and can be problematic, and is oft done poorly by the NRTL. Few technicians understand the physics of the Seebeck effect, and fewer understand component performance and function for modern power conversion equipment that would affect thermocouple performance. During previous 18 to 20 years, have seen only two particular instances of an NRTL lab doing the heating test where the data was both repeatable (error band coincident with uncertainty) and the test conditions were correct (this is out of over 20 visits to various labs on behalf of clients). R/S, Brian From: Kevin Robinson [mailto:kevinrobinso...@gmail.com] Sent: Tuesday, September 20, 2016 6:59 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: [PSES] Measurement Accuracy I was wondering if anyone was aware of any guidance documents that provided acceptable levels of uncertainty when conducting various tests. The specific measurement that I am interested in this case is temperature measurements, but I would be interested in seeing other guidance for other measurements as well (voltage, current, force etc.) I know the IECEE has published a CTL decision sheet on equipment accuracy, but I was wondering if there was other industry guidance available. I have a situation where a product was subjected to a temperature test three times by three different individuals using the same test equipment, and the delta in some instances was nearly 12 degrees C (53.3 - 64.8) for the same component. Just looking for some additional guidance documents or standards that would help me convince the powers that be that such errors are unacceptable. Kevin Robinson - ---------------------------------------------------------------- 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 <emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <sdoug...@ieee.org> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com>
