Proficiency testing of electromagnetic compatibility (EMC) labs in Brazil by measurement comparisons

This work reports the analysis and main results of a recently concluded proficiency testing round with the major electromagnetic compatibility (EMC) laboratories in Brazil. Seven labs conducted radiated emission measurements at their test facilities under the coordination of an independent third party supervised by the Brazilian accreditation body, INMETRO. Six of them are currently the only labs accredited on EMC measurements in Brazil. The guidelines of international standards such as ISO/IEC Guide 43 and ISO 13528 were followed, while the scope of the tests focused on EMC compliance of information technology devices, based on CISPR 22. A multi-tone signal generator was specifically designed and assembled for the present proficiency testing conditions. Statistical metrics such as z-score and normalized error have been adopted to assess global and individual performances of the participant laboratories. The normalized error indicated 10 unacceptable results out of 35 results, while only 3 out of 35 z-scores were out of the acceptance range. Considering that the participant labs are actually only for test measurements (not for calibration), the overall performance may be taken as satisfactory, based on the fact that the z-score should be used in this case