电流比较仪的磁屏蔽是减小磁性误差,提高测量精度的重要组成部分,但实际中磁屏蔽往往存在气隙导致屏蔽效能下降,影响比较仪的测量精度。通过建立有限元模型,研究磁屏蔽上引线穿出气隙对屏蔽效能的影响,得到了屏蔽效能随气隙高度变化的规律。对于该模型,气隙高度小于10 mm时,屏蔽效能下降不大;当气隙高度大于10 mm后,屏蔽效能下降明显。最后,搭建实验平台验证气隙对屏蔽效能的影响,实验结果与有限元计算结果相吻合,小气隙对屏蔽效能的影响不大,当气隙超过一定高度后对屏蔽效能影响很大,实际设计中应予以避免。
Abstract
Magnetic shield of the current comparator is an important structure to decrease the magnetic error and ensure high measurement accuracy and its ability is defined by the magnetic shielding effectiveness. Considering the air gap caused by wires through the magnetic shield, a finite element method (FEM) model is established to study the relationship between air gap length and magnetic shielding effectiveness.To this specified size of model, the FEM results show that when the air gap length is lower than 10 mm, the magnetic shielding effectiveness is almost unaffected, while when the air gap is larger than 10 mm, it decreases dramatically. Finally, an experimental device is built to verify the effect of air gap on the shielding effectiveness. The FEM results and experiment results both draw a conclusion that small air gap have little effect on magnetic shielding effectiveness, while when air gap reach a certain length it will have a significant deteriorate effect, so in application the air gap should be constrained to a proper length.
关键词
计量学 /
电流比较仪 /
磁屏蔽效能 /
气隙 /
有限元法
Key words
metrology /
current comparator /
magnetic shielding effectiveness /
air gap /
finite element method
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基金
国家电网公司纵向科技项目 (JL-71-15-048)
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