RESUMO
The traceability method directly affects the reliability and accuracy of the measurement of electronic transformers. The stability and unreliable traceability performance of analog devices would affect the traditional analog differential method. Thus, we propose a digital differential method combining a time series-weighted correlation degree extension integrating Hilbert phase-shift of four-term continuous third-derivative Nuttall window function, effectively suppressing the end effect problem and realizing the high-precision addition of the differential. Results of simulation experiments showed that the differential's deviation was <10-10, much less than that (1.32 × 10-4) due to the analog differential. The voltage and current ratio difference's combined standard uncertainty was 5.01 × 10-5 and 5.08 × 10-5, respectively, and 0.1718' in the phase error. Finally, an automatic traceability detection system was constructed. Compared with the traditional method, the accuracy and stability of the automatic system were better and could meet the traceability requirements for 0.05-accuracy electronic voltage transformer calibrator.
