Bilateral comparison of 1 Ohm, 10 kOhm and 100 MOhm resistance standards between the PTB and the UME

In order to evaluate the agreement between the Physikalisch-Technische Bundesanstalt (PTB, Germany) and the Ulusal Metroloji Enstitusu (TUBITAK-UME, Turkey) and to establish a firm basis for traceability, a bilateral comparison has been carried out using 1 Omega, 10 k Omega and 100 M Omega resistors. Measurements obtained by the PTB, based on their quantum Hall resistance standard (QHRS), differ from the UME results by 46 n Omega/Omega (standard uncertainty u = 0.19 mu Omega/Omega) at the 1 Omega level, and by 3.0 n Omega/Omega (u = 0.25 mu Omega/Omega) at the 10 k Omega level. The 100 M Omega resistors were compared using both a UME-constructed Wheatstone bridge and a commercial bridge. Measurement results obtained with the Wheatstone bridge show better agreement with those of the PTB, within 0.34 mu Omega/Omega (u = 8.7 mu Omega/Omega), than the results obtained with the commercial bridge, within 3.6 mu Omega/Omega (u = 5.1 mu Omega/Omega).