Low voltage AC-DC transfer standards at LNE
This paper describes the method used to establish the traceability of LNE AC-DC transfer standards in the mV-range to the 1 V multijunction converter, which serves as the primary AC-DC standard. Main uncertainty components are listed and final uncertainty given for the different voltage levels. An independent method was developed for the calibration of thermal converters at 0.3 V and 0.2 V. The agreement between this method and the step-down is within the standard uncertainty.
Recharacterization of thermal voltage converters after thermoelement replacement
This paper describes the relationship between the characteristics of various thermoelements (TE's) as voltage or ourrent converters and the overall ac-dc differences of a voltage range. An algorithm is presented to predict the ac-dc differences of series resistors with different TE's, and a method for recharacterizing a thermal voltage converter containing a replacement TE is given. The measured results show that for most applications, a complete recharacterization of the TVC set is unnecessary.
An accurate AC-Dc voltage transfer standard test system using the differential and the dual-channel method
In the Electrotechnical Laboratory (ETL) the accuracy of the AC-DC voltage transfer difference was improved for the voltage range of 1-20 V in the frequency range from 10 Hz to 100 kHz. At the same time, the AC-Dc transfer standards and the measurement system which is used in the Japan Electric Meter Inspection Corporation (JEMIC) were also improved. The system is realized by applying an improved differential and a dual-channel method. The test repeatability is better than 1 ppm for nominal test voltages. The voltage and frequency measurement ranges are extended up to 200 V and up to 1 MHz. The whole system is controlled by a desktop computer with an optically isolated GP-IB bus system. >