Demagnetization of instrument transformers before calibration

Karel Draxler – Renata Styblíková

   This paper describes the influence of magnetization of an instrument current transformer (ICT) core on ICT errors, and presents a procedure for demagnetizing an ICT. The dependence of ICT errors on the magnetization of the ICT core for different magnetic materials is given in the paper, together with a detailed procedure for ICT demagnetization. The results of experiments are summarized, and conclusions are drawn on when ICT demagnetization is necessary, and on how to prevent the destruction of an ICT due to its winding being punctured.

Keywords: instrument current transformer, AC current, ratio error, phase displacement, magnetization

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