Bilateral international inductance comparison using traveling standards in thermoregulated enclosures

Standards with toroidal windings are traditionally used for international comparisons of inductance. The achieved uncertainties of the comparisons are dominated by the rather high temperature coefficient of the traveling standards. Hence, thermoregulated enclosures were developed at PTB a few years ago. These have now been refined and their suitability for the transportation of standards has been proven in a bilateral comparison between PTB and VTT. The agreement was excellent, while the overall uncertainty of the comparison varied from 14 μH/H to 62 μH/H in the frequency range 100 Hz to 2 kHz.