钳形电流表校准不确定度的分析与评定

Analysis and Evaluation of Uncertainty of Clamp Ammeters Calibration

钳形电流表理想的校准方法是用标准电流源对一根无限长导线加测试电流,并使该导线垂直穿过被校钳形表的几何中心。根据等安匝原理,实验室常用多匝校验线圈代替单根导线对钳型表进行校准,如此只需小电流即可对钳形表大电流量程进行校准,但是校验线圈这种校准方法会引入新的测量不确定度。本文分别从被测导体偏心度和倾斜度以及不同校验线圈对钳形表铁心磁感应强度的影响等几方面进行分析,并给出钳形电流表校准不确定度评定的具体方法与步骤。

An infinite wire carrying standard high current perpendicular to the geometric center of the clamp ammeter should be the ideal method for the clamp ammeters calibration. It is impractical in laboratory calibration with this infinite single wire which can be replaced by an N-turn coil. According to the equal ampere-turn principle, it is feasible to calibrate the high current range of the clamp ammeters with low current. However, the calibration coil brings new uncertainty into the calibration. This paper emphasized on the effect of the displacement of the wire from the core center and the effect of the rotation of the core, two shapes of commonly used N-turn coils were analyzed, the detailed steps for the uncertainty evaluation of clamp ammeters were given finally.