Heavy DC Current Calibration Method Based on High-Precision Current Adder

Traditional calibration method of the main sensor measuring the total dc current in the electrolysis industry is that the main sensor is calibrated by the standard measurement device for high dc current. However, as the total dc current has increased to hundreds of thousands amperes, the standard measurement device is troubled by problems of its size, complexity, and expense. To solve these problems, a novel method of calibrating the main sensor is presented. This method is based on high-precision dc current adder, which can add all the output currents of branch dc current sensors directly with the accuracy of 0.005%. The error compensation principle and the common divisor principle are presented to solve the problems caused by the measurement errors and different ratios of the branch sensors. At last, through the self-calibration experiment of the dc current adder, the accuracy of the adder is proved to be better than 0.005%.