High-precision AC-DC transfer standards at ETL

A new measurement system is developed in order to re-evaluate the present AC-DC transfer standards of the Electrotechnical Laboratory (ETL). The measurement system consists of a high-precision comparator system and a modified fast-reversed DC source. The AC-DC transfer differences of thermal transfer standards are compared using the comparator system with a resolution better than 1 ppm. The absolute AC-DC transfer differences of single-junction thermal converters (SJTCs) are evaluated in term of a multijunction thermal converter and by the modified fast-reversed DC method. The results obtained by the two methods agree within 1 ppm.<>