空心线圈电流互感器传变特性实验研究和分析

摘要

为了精确评估空心线圈电流互感器的传变特性，设计了空心线圈电流互感器精确度、饱和特性、频率特性和暂态特性的测试方案，根据互感器的结构模块设置测试点，研究各单元部件和整机的特性。提出采用“额定准确低限值一次电流”下的“总谐波畸变率”指标，评价空心线圈电流互感器在小电流时的输出波形质量。实验结果表明，空心线圈电流互感器大电流时线性度好，小电流时易受干扰的影响，互感器频带受限于传感线圈参数和信号处理电路的相频特性，对故障暂态电流和励磁涌流的传变误差主要来源于衰减直流分量的测量误差。研究方法为厂家产品设计和改良、相关测试标准的改善提供参考。%For accurately assessing the transfer characteristics of the air⁃core current transformer, the test scheme is designed on its accuracy, saturation, frequency and transient characteristics. The test points are set according to structure module of the transformer, and the characteristics of the each unit and the whole machine are studied. The index of‘total harmonic distortion rate’ under the‘rated accurate low limit primary current’ is proposed so as to evaluate its output waveform’ s quality when the current is small. The experimental results show that the air⁃core current transformer has good linearity when current is strong and is susceptible to interference with the small cur⁃rent, the frequency band of current transformer is limited by the sensing coil parameters and phase frequency char⁃acteristic of signal processing circuit, and the transmission errors of transient current and excitation inrush current come from the measurement error of decaying DC component mainly. The research method can provide verification for the improvement of manufacturer’ s product design and related test standards.