Design of a Real-Time Detector for Solution Conductivity Based on Conductivity Electrode

Abstract:

In order to realize real-time detecting for solution conductivity, an on-line detector powered with 9V battery was developed. The detector consists of conductivity electrode, excitation signal generating circuit, RMS detecting circuit, MSP430F2132 microcontroller, DS18B20 temperature sensor, HT1621 displayer and SPI interface. The solution conductivity was measured according to the principle that the electrode’s output resistance varying with conductive ions concentration of the solution, the measured results could be displayed on HT1621 and be sent to other controllers through SPI interface. An optimum excitation signal that a square wave signal (the amplitude was ±3.5V, and the frequency was 1.8 kHz) had been determined by experiments, to minimize polarization effect of the conductivity electrode. Verification test had been performed for the detector, the tested results showed that maximum relative error of the detector was 2.94%, could meet the requirement of practical application.

• Periodical: Advanced Materials Research (Volumes 986-987)
• Pages: 1477-1480
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.986-987.1477
• Online since: July 2014
• Authors: Jia Nian Li*, Yan Ma, Rui Feng, Hui Na Ni
• Keywords: Conductivity, Conductivity Electrode, Real-Time Detecting, Solution

References

[1] Li Jianian, Hong Tiansheng, Feng Ruijue, et al. Design and experiment of automatic mixing apparatus for liquid fertilizer based on fuzzy control[J]. Transactions of the Chinese Society of Agricultural Engineering, 2013, 29(16): 22-30.

[2] Liu Zhenming, Qi Chuanhui, Wang Yunlong, et al. Based on P89C51 automatic monitor control system for on-line nutrient consistency[J]. Journal of Agricultural Mechanization Research, 2010(10): 83-86.

[3] Jia Kejin, Zhang Xiaowei, Lin Bo, et al. The intelligent on-line conductivity analyzer based on MSC1210 single chip computer[J]. Process Automation Instrumentation, 2007, 28(5): 43-46, 50.

[4] Chen Gehua, Teng Yujuan, Wang Xiaohui. A new way to measure conductance[J]. Journal of Northeast China Institute of Electric Power Engineering, 2005, 25(6): 76-78, 91.

[5] Chen Xiaoping, Chen Hongxian. Double frequency method to measure water conductivity[J]. Chinese Journal of Scientific Instrument, 2006, 27(5): 520-522.

[6] Li Lin, Chen Wenxiang. Electrical conductivity measurement using frequency self-adaptation current source to surmount the influence of capacitance[J]. Chinese Journal of Scientific Instrument, 2007, 28(12): 2256-2259.

[7] Sudduth K A, Kitchen N R, Bollero G A. Comparison of electromagnetic induction and direct sensing of electrical conductivity[J]. Agronomy Journal, 2003, 95(3): 472-482.

DOI: 10.2134/agronj2003.4720