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钳式微电流传感器具有工程安装方便的优点,在电气设备绝缘监测中应用广泛。由于安装过程中开口气隙的不一致,加之野外运行温差较大造成信号处理电路温漂和参数变化,致使在实验室严格调试的高精度微电流传感器,运行时会产生较大误差,并且各个传感器的变比也会偏离设计值。为此,提出了基于标准电流注入的微电流传感器在线定标方法,运行时在原边注入1个标准的定标电流信号,该信号的频率应避开传感器工作电流所含有的工频和一定幅值的谐波频率;然后从传感器信号处理电路的输出端得到定标信号,进而计算实际标度,根据此标度就可计算出实际泄漏电流。实验得到的传感器精度可以达到±0.05%,实验室和现场实验验证了提出方法的有效性和准确性。
Clamp micro-current sensor has the advantages of easy installation, widely used in the insulation monitoring of electrical equipment. Due to the inconsistent open air gap in the installation process and the large temperature difference of the field operation caused by temperature drift and parameter variation of the signal processing circuit, the precision micro-current sensor that is strictly debugged in the laboratory will have a large error during operation and each sensor The ratio will deviate from the design value. Therefore, a method of on-line calibration of micro-current sensor based on standard current injection is proposed. One standard calibration current signal is injected into the primary side during operation. The frequency of this signal should be kept away from the working frequency and amplitude Value of the harmonic frequency; and then from the sensor signal processing circuit output calibration signal obtained, and then calculate the actual scale, according to this scale can calculate the actual leakage current. Experimental accuracy of the sensor can reach ± 0.05%, laboratory and field experiments verify the effectiveness and accuracy of the proposed method.