The Development Of A New Industrial Electrical Conductivity Instrument

Electrical conductivity measurement technique is one of important parameter measurement techniques, which has been widely used in scientific research work and industry. In this paper, the electrode electrical conductivity measurement method is deeply studied.Based on the excitation of bi-directional Voltage Pulse Technique, a new electrical conductivity instrument is presented. Testing result shows that the sampling interval time of the instrument is 1.202ms, that measurement error is less than 0.5% and that the instrument can be used in industry for real-time measurement. The main works are listed as follows:(1) Compared with traditional AC excited electrical conductivity system, the developed system is excited by bi-directional pulse voltage source. Through fast bi-directional voltage switching, the polarization effect is abated. During the data acquisition,the system is regarded as being excited by a constant direct voltage point, which can improve the rate of data acquisition and simplify the circuit of electrical conductivity instrument system.(2) Through multiple measurements of standard resistance, the proposed instrument was calibrated by adopting linearity fitting method and five calibration models were obtained in different measurement range. After acquiring a measured value, a method, which can implement automatic temperature compensation through microcomputer's on-line look-up table, is adopted. Results show that the measurement error is less than 0.5% after the calibration.(3) An electrical conductivity sensor is designed to be used in heavily polluted industrial field or environment with strict hygienic requirement. The sensor avoided the electrochemical reaction and had the function of temperature compensation.