[303690] Artigo – SEMETRO – Congresso Internacional de Metrologia Elétrica

Resumo:  The traceability chain of electrical resistance in Brazil relies upon standard resistors of 1 Ω and 10 kΩ maintained by the Electrical Standardization Metrology Laboratory (Lampe) at the Inmetro. These standard resistors are periodically calibrated at the Bureau International des Poids et Mesures in France to ensure traceability to the International System of Units. Transport can influence the properties of the resistors and change their values. Lampe checks resistors’ changes before and after calibration at the BIPM. The highest differences tend to occur with the 1 Ω resistors. However, drift rate evaluation becomes arduous when the check results show small changes in the values – of about 0.10 μΩ/Ω – due to the uncertainty components involved. In this work, the step-down is a procedure to measure the 1 Ω resistors through a 10 kΩ resistor. The comparison of results between Lampe and the Quantum Electrical Metrology Laboratory shows a relative difference of less than 0.05 μΩ/Ω. The results agreement allowed Lampe to confidently use the step-down method to evaluate 1 Ω resistors’ drift.