Establishment of High-Voltage AC–DC Voltage Transfer Standards in 1–100-kHz Range at NMIJ

New thin-film range resistors have been developed at the National Metrology Institute of Japan, to re-establish ac-dc voltage transfer standards in the 100-1000-V range at frequencies of 1-100 kHz. In earlier studies, the voltage dependence of the ac-dc transfer difference was observed during step-up procedures above 300 V. One of the possible reasons for this voltage dependence is the temperature rise due to the Joule heating, which may cause changes in the resistance of the resistor, as well as the temperature dependence of the dielectric losses in the resistor coating. In this paper, to reduce the voltage dependence, new thin-film heaters were directly fabricated on an aluminum nitride substrate to prevent heat from accumulating in the range resistor. The voltage dependence was evaluated by measuring the differences in impedance among various range resistors. Negligible voltage dependence in the step-up procedures from 100 to 1000 V was achieved.