接地网腐蚀状态电化学检测传感器的研制

Development of an Electrochemical Detection Sensor for Grounding Grid Corrosion

研制了接地网腐蚀电化学原位检测传感器,通过把辅助电极封闭在绝缘腔体(碳钢套管)中,使极化电流通过绝缘腔体底部的小孔流向工作电极,实现了传感器的限流作用。采用限流传感器测量了恒电流阶跃的响应电位-时间曲线(E-t曲线),并采用E-t曲线拟合软件得到了被测量接地网金属的极化电阻。通过测量接地网金属的极化电阻研究了传感器的限流效果以及传感器限流孔直径和插入土壤中的深度对测量面积的影响。研究结果表明:限流传感器测量面积约为传统传感器的测量面积的1/80;传感器的限流孔直径被确定为5 mm;在12.5 cm深度范围内,传感器插入土壤中的深度对限流效果影响不大。无需开挖或停运接地网,采用限流传感器可以准确、快速和经济地检测不同测量位置处的接地网的相对腐蚀程度。

An electrochemical detection sensor for grounding grid corrosion was developed. Because the auxiliary electrode used to polarize the working electrode was encapsulated into insulation cavity（ carbon steel）,the polarization current was made to flow through the pinhole to the working electrode and the confinement function of the sensor was implemented. The potential time curve as a response to a galvanic step（ short for E-t curve） was measured with the sensor and the polarization resistance was obtained by E-t curve fitting software. The impact of the sensor hole diameter and the insertion depth into the soil on the measurement area were studied through measuring the polarization resistances of the grounding grid. The investigation results show that the optimum sensor diameter is 5 mm,the insertion depth of the sensor has small impact on the current confinement at a range of 12. 5 cm,the ratio of area measured with current confinement sensor to that measured with traditional one is about 1 /80. This sensor was successfully used to carry out corrosion detection for a substation grounding grid without excavating the grounding grid or stopping its operation.