A simple control and high accuracy measurement method of open-cell four-electrode conductivity electrode

Abstract

The paper presents a simple control and high-accuracy measurement method for a four-electrode conductivity probe based on the principle of the bi-directional voltage pulse. The two-way differential AC (alternating current) pulse voltage signal for the reference resistance and solution resistance is modulated into the single DC stationary voltage response signal to drop the demand for software and hardware and effectively eliminate the influence of excitation voltage pulse amplitude on measurement accuracy, and then the synchronous rectification DC measurement is proposed without any control timing. Meanwhile, the mathematical expression between the single output DC voltage signal and the solution conductivity is given. The test results in the laboratory and in the field indicate that the relative error of the conductivity measurement is within 2.5% in a conductance range of 10 uS/cm to 200 mS/cm, and the proposed measurement method has a good application prospect in application.