泄漏电流对电流互感器误差特性的影响及分析

Effect and Analysis of Leakage Current on Error Characteristics of Current Transformer

目前在低压状态下对输电系统中的电流互感器开展误差检测,检测条件与实际运行条件不一致,导致检测数据不能准确反映其运行时的实际误差特性,从而导致较大的电能错误计量或对电流互感器计量性能合格性做出错误评判。分别通过理论、仿真和试验等多种方式深入分析泄漏电流对电流互感器误差特性的影响。结果表明,泄漏电流会使电流互感器误差向负方向偏移;电流较小时(特别是20%额定电流以下),泄漏电流影响较大,随着电流增大,泄漏电流影响逐渐减小,当电流增大到一定程度时,泄漏电流对电流误差的影响可以忽略;建议采用在运行电压下直接测试的方式对电流互感器开展误差检测。

The error of current transformer in transmission system is tested at low voltage presently, and the inconsistence between testing condition and operational condition may result that tested data cannot reflect the error characteristic of current transformer precisely, which will lead to seriously wrong electric energy metering and even misjudgment on the qualification of the metering characteristics of current transformer. In this paper, effect of leakage current on error of current transformer was analyzed by means of theory, simulation and experiments. Testing results show that leakage current makes the value of the error smaller, and the effect becomes more significant with smaller current. In addition, the effect of leakage current on the error of current transformer can be neglected once current increases to a certain value. It is suggested that the error of current transformer should be tested at operational high voltage directly.