in general, the test standards prescribe the accuracy / type of equipments and method to be used for testing. This means that measurement uncertainty has been specified indirectly. In such cases, where we are following these guidelines, the pass/fail decision can be taken based on the limits given in standard , without taking into account the uncertainty. If any of these guidelines are not being followed and resulting in higher uncertainty, the decision of pass/ fail needs to taken after due consideration of measurement uncertainty. More and more standards are now defining uncertainty factors in details for example EMC standards; however I agree that many are still not very clear, requiring engineering judgment to be taken.
Best regards B M Vyas From: Boštjan Glavič [mailto:bostjan.gla...@siq.si] Sent: Wednesday, September 21, 2016 9:22 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Measurement Accuracy Measurement uncertainty depends on instruments used, method used etc. Each lab has to do calculation of measurement uncertainty for particular method. Measurement uncertainty becomes critical when results are close to the limit. High uncertainty means you have more chance to be in »a grey area« where result needs to be defined as pass or fail. Laboratory needs to inform the client about value of measurement uncertainty if requested. Example, if your measurement uncertainty of temperature measurement method with thermocouples is 3°C, limit according to standard is 85°C and you measure 84°C then you are in a grey area. In this case you can make result as Pass however client needs to be informed about your measurement uncertainty. ISO GUIDE 115 give you some guidance how to do calculation, but no document specifies limits of measurement uncertainty. Hope it helps. Best regards, Bostjan From: Brian O'Connell [mailto:oconne...@tamuracorp.com] Sent: Wednesday, September 21, 2016 12:54 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Measurement Accuracy ISO, International Standardization Organization, Guide to the Expression of Uncertainty in Measurement, GUM ISO, General Requirements for the Competence of testing and calibration laboratories, ISO 17025 http://www.bipm.org/en/publications/guides/gum.html Brian From: Richard Nute [mailto:ri...@ieee.org] Sent: Tuesday, September 20, 2016 1:18 PM To: EMC-PSTC@LISTSERV.IEEE.ORG<mailto:EMC-PSTC@LISTSERV.IEEE.ORG> Subject: Re: [PSES] Measurement Accuracy I was wondering if anyone was aware of any guidance documents that provided acceptable levels of uncertainty when conducting various tests. I didn’t know what “uncertainty” is, so I did a Google search and found this reference: https://www.wmo.int/pages/prog/gcos/documents/gruanmanuals/UK_NPL/mgpg11.pdf Of particular interest is 1.2, which discusses “pass-fail.” In both product safety and EMC compliance, the result is “pass” or “fail.” The document says: “Often, a test is not a measurement: tests normally lead to a ‘yes/no’ answer or a ‘pass/fail’ result. (However, measurements may be part of the process leading up to a test result.)” So, our standards specify tests and test limits, pass or fail. Just looking for some additional guidance documents or standards that would help me convince the powers that be that such errors are unacceptable. Well, according to the document, you need to take into account what you call “errors” as they are not errors but different measurements that need to be accounted for in determining the “pass-fail.” At the end of the document are two references, which are much more detailed. 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 <emc-p...@ieee.org<mailto: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)<http://www.ieee-pses.org/list.html> List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <sdoug...@ieee.org<mailto:sdoug...@ieee.org>> Mike Cantwell <mcantw...@ieee.org<mailto:mcantw...@ieee.org>> For policy questions, send mail to: Jim Bacher <j.bac...@ieee.org<mailto:j.bac...@ieee.org>> David Heald <dhe...@gmail.com<mailto:dhe...@gmail.com>> - ---------------------------------------------------------------- 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<mailto: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)<http://www.ieee-pses.org/list.html> List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <sdoug...@ieee.org<mailto:sdoug...@ieee.org>> Mike Cantwell <mcantw...@ieee.org<mailto:mcantw...@ieee.org>> For policy questions, send mail to: Jim Bacher <j.bac...@ieee.org<mailto:j.bac...@ieee.org>> David Heald <dhe...@gmail.com<mailto:dhe...@gmail.com>> - ---------------------------------------------------------------- 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<mailto: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)<http://www.ieee-pses.org/list.html> List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <sdoug...@ieee.org<mailto:sdoug...@ieee.org>> Mike Cantwell <mcantw...@ieee.org<mailto:mcantw...@ieee.org>> For policy questions, send mail to: Jim Bacher <j.bac...@ieee.org<mailto:j.bac...@ieee.org>> David Heald <dhe...@gmail.com<mailto:dhe...@gmail.com>> This e-mail and any files transmitted with it are for the sole use of the intended recipient(s) and may contain confidential and privileged information. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies and the original message. Any unauthorized review, use, disclosure, dissemination, forwarding, printing or copying of this email or any action taken in reliance on this e-mail is strictly prohibited and may be unlawful. The recipient acknowledges that Ymllabs.com or its subsidiaries and associated companies (collectively " Ymllabs.com "),are unable to exercise control or ensure or guarantee the integrity of/over the contents of the information contained in e-mail transmissions and further acknowledges that any views expressed in this message are those of the individual sender and no binding nature of the message shall be implied or assumed unless the sender does so expressly with due authority of Ymllabs.com. Before opening any attachments please check them for viruses and defects. In case you have any problem or issue with the E-mails from YMLLABS.com, Please do lets us know on netad...@ymllabs.com Ymllabs.com Udaipur- Rajasthan -313001 - ---------------------------------------------------------------- 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>
