Testing the new generation of low-frequency current comparators

Improved magnetic materials open the perspective of operating room-temperature current comparators at lower frequency without compromising metrological accuracy. Two prototypes of low-frequency current comparator (LFCCs) have been successfully tested in precision resistance ratio measurements at drive frequencies of 0.5 Hz and 1 Hz using the BIPM's bridge setup with a recently realized frequency extension. These measurements have been performed using standard resistors of 10 kΩ, 1 kΩ and 100 Ω nominal values as well as the quantized Hall resistance (QHR) of GaAs and graphene devices.