New ac-dc transfer step-up calibration and uncertainty calculation in PTB and INTI

In PTB and INTI new ac-dc voltage transfer standards are built for the voltage range of 0.1 V to 1000 V and the frequency range of 10 Hz to 1 MHz. PMJTC (Planar Multijunction Thermal Converters) and coaxial voltage dropping resistors are used in the step-up procedure for the different voltage levels. For voltages >100 V new planar resistors are used to guarantee voltage independence of the ac-dc transfer difference. The high sensitivity of the PMJTC allows big steps in the step-up calibration and many steps inbetween which leads to an overdetermined system to check the validity of the assumptions used in the step-up. The uncertainty budget for the different voltage levels is calculated.