电流互感器剩磁相关参数测量的直流法

DC Method for Measuring Parameters of Remanence of Current Transformer

对电流互感器剩磁相关参数测量的传统方法在消磁不充分时测取的剩磁系数偏小,为了消除其对电流互感器准确级评定判断造成的偏差,提出了一种新型直流法,省略了测试前对铁芯退磁的操作。在传统直流法的基础上增加反向充电到电流互感器饱和状态这一过程,测取正向充电过程、放电过程、反向充电过程的励磁电流与互感器二次侧端子电压,进行积分运算得到磁通变化量,再对这3个磁通变化量运算,可在一次测试过程中准确得到电流互感器的初始磁通及剩磁系数。实验结果表明:当消磁不充分时,传统直流法测取的剩磁系数为0.189,新型直流法测取的结果为0.234,传统直流法导致了-21%的偏差,而新型直流法克服了此测量误差。

The remanence factor obtained by traditional measuring methods for parameters of current transformer remanence is less than the expected when the transformer is degaussed deficiently, which leads to deviation in the judgment of current transformer accuracy class. Thus, we proposed a DC method that bypasses the demagnetization of iron core. Based on traditional DC methods, the proposed one introduces a process of reversely charging current transformer to sa- turation. By measuring field current and the voltage in the secondary side of current transformer in positive charging process, discharge process, and the reversely charging process, the change of magnetic flux is acquired by integrating the above voltage and current. Moreover, by calculating the three variations, we can accurately obtain the initial flux and remanence factor of a current transformer in one test. Further experiment indicates that, for a deficiently degaussed current transformer, its remanence factor is 0.189 measured by traditional DC method and 0.234 measured by the proposed DC method, showing that the traditional DC method leads to deviation of-21% while the proposed novel DC method over- comes the deviation.