Automation and evaluation of two different techniques to calibrate precision calibrators for LF voltage & current using thermal devices

Low Frequency (LF) voltage and current are important parameters in Electrical Metrology. The standards for LF voltage and current are established by assigning AC-DC transfer difference to thermal devices i.e. thermal converter (TC) or thermal transfer standard (TTS) alongwith current shunts. Automated calibration systems have been developed using Null and Budovsky´s techniques for calibration of precision calibrator for LF voltage and current using thermal devices (TC/TTS) alongwith current shunts. The technique based on the Algorithm developed by Dr. Ilya Budovsky (N.M.I. Australia) has been compared with the conventional null technique. The softwares have been used to calibrate the calibrator in the entire LF voltage and current range using Holt converters and current shunts. Calibration results at 1V and 10V level in the frequency range from 10Hz to 1MHz are presented in this paper. The results show that the Budovsky´s technique has reduced the complexity of AC-DC transfer measurements, measurement time and the uncertainty in measurement at some points.