二次侧压接对电流互感器自动化检定的影响分析

在低压电流互感器室内自动化检定系统中,互感器的二次侧采用压针结构实现自动化接线,压针式接线柱相较于传统压接方式易于实现自动化接线,但接线的稳定性无法得到完全的保障。由于互感器在检测位的放置精度及探针下压精度的影响,互感器与探针的接触面大小及接触压力有明显变化,进而造成接触电阻偏离理论值,最终影响检测结果。本文列举了金属接触面接触电阻的主要来源,并介绍了影响接触电阻大小的几类常见因素。在此基础上,对电流互感器检测回路建立了电路模型,在复数域推导了接触电阻与检定误差的关系,定量分析了接触电阻改变对检测结果的影响,并提出了一些减小影响的措施。分析结果在省级低压电流互感器集中自动化检测线中得到了验证。

Analysis of the effect of secondary side crimping on automatic verification of current transformer

In the in door automatic verification system of low voltage current transformer, the probe terminal structure is adopted to realize the automatic crimping of the secondary side of the current transformer, which can realize automation more easily compared with traditional crimping methods; however the stability of the crimping cannot be ensured completely. Due to the crimping and placing accuracy at the test station of the transformer, the contact area and pressure between the transformer and probe terminal can vary considerably, which makes the contact resistance drift off the theoretical value and finally affects verification results. This paper enumerates the main sources of the contact resistance and introduces several common factors affecting the contact resistance. On this basis, a model of the current transformer detection circuit is built, the relationship between contact resistance and calibration error is derived in complex domain, and the influence of contact resistance on detection result is analyzed quantitatively. Besides, some measures for reducing the influence are proposed. The analysis results were verified in the provincial centralized automatic verification line of low-voltage current transformer.