| The electrical conductivity (EC) of solution is an important parameter of water. It is widely used in electricity, chemical industry, environmental protection, pharmacy, metallurgy, biochemistry, and food and water industry. Because electrode EC measurement uses electrode, simple structure wide measuring range and low cost, it has been widely used in industrial production process. In this paper, the electrode EC measurement method is deeply studied.After referring many references at home and abroad, the author analyzed the electrode conductivity measurement method's influencing factors, mainly polarization effect, capacitance effect, and the temperature effects, according to the mechanism and solution conductivity electrode solution in the role model. Against these effects and all sorts of problems traditional conductivity measurement method are facing, the author developed a new kind EC instrument, which used bi-directional with pulse voltage source. Compared with traditional instruments used AC, this instrument's circuit has simple structure, large measurement range and high precision. Against temperature's influence on EC, it is usually used temperature compensation, but the traditional method of temperature compensation is cumbersome and unsatisfactory. In this paper, PC is used for auto-temperature compensation with online look-up table method.Using the chip AT89C55 as core, the EC meters adopts high accuracy A/D for data collection. In this paper, circuits have been designed, and USB Interface has been supplied to communicate with PC. The system manages power automatically and data is calculated by using matlab. Micro-controller can automatically adjust the temperature compensation factor and measuring range.After testing and demarcating with liquid calibration, the system's relative error is less than 0.5%. USB interface has been extended and can be used in industry for real-time measurement. After further improvement, this system can be used in industrial processes.
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