Temperature characteristic analysis on electronic current transformer

Measuring accuracy is a key parameter for electronic current transformer (ECT), but the temperature variation of the surrounding environment may influence its measuring accuracy. Temperature-dependent accuracy is one characteristic for ECT compared to traditional current transformer and it is a key parameter to be analyzed during the development of ECT. According to the function of an ECT based on low power current transformer (LPCT), several sub-systems are decomposed by this paper. Temperature-dependent accuracy of these sub-systems is analyzed and the expressions on temperature dependence of LPCT and the amplifiers in the electronic circuitry in high voltage side are proposed. One type of electronic current transformer was developed and passed the type test in the national authoritative department of China. The test results show that the transformer developed by this paper fulfils IEC 0.2 class accuracy requirements and achieves accuracy within ±0.1% in ratio error and ±4′ in phase error at 25-50°C. The validity of the analysis is confirmed by the results.