Design and implementation of an industrial C4D sensor for conductivity detection

A capacitively coupled contactless conductivity detection (C4D) sensor suitable for conductivity detection of electrolyte solution in industrial fields is developed. Series resonance principle is adopted to remove the influence of coupling capacitances and hence to implement the conductivity detection in large pipelines. A special shield configuration is designed to eliminate the influence of the stray capacitance, to overcome the negative influence of the interference in industrial fields and to be suitable for the metal connection in industrial fields. Conductivity detection experiments were carried out on four different sized pipes with inner diameters of 1.8 mm, 3.3 mm, 5.0 mm and 7.6 mm, respectively. The experiment results show that the C4D sensor for industrial application is successful and the accuracy of conductivity detection is satisfactory. Discussions concerning the advantages and disadvantages of the C4D sensor are presented.