Research on improvements of using electronic current transformer on distance protection

Traditional magnetic current transformer (CT) always has the problem of saturation, which depresses the accuracy of distance protection's impedance measurement and shortens its protection zone. Based on this analysis, traditional measures to solve this problem are summarized first, and then the newly developed electronic current transformer (ECT) is introduced as a new way to solve the problem. Because of its high accuracy, high stability, wide frequency band, and most of all, without the problem of magnetic saturation, ECT has become a popular substitute for traditional CT. It can improve the starting unit, phase selecting unit, impedance unit and other functional units of distance protection. Experimental analysis shows that using ECT instead of traditional CT can enhance the operating accuracy and reliability of distance protection greatly.