水质自动监测系统中单位电导率测量的原理与设计

溶液中的单位电导率通常采用尔劳施（Kohlrausch）电极进行测量，并根据溶液电导率的温度系数对单位电导率进行补偿。在本设计中，电导率和温度在传感器侧就近进行检测并采用压频转换器转换为频率，频率信号通过光电偶合器很容易实现传感器和控制器间的隔离，解决了噪音、安全和远距离传输问题，并以低的成本获取高的模数转换精度。

Principle and Design of Conductivity Measured in Water Quality Automatic Monitoring System

Conductivity in liquid usually is measured by Kohlrausch electrode, and compensated for the conductivity according to the temperature coefficient of the conductance. In design, conductivity and temperature are detected by sensors, and converted to frequency by the use of voltage-to-frequency converters. A pulse train can easily be isolated from the controller of the system by using optocoupler, which solves the problem of noise, safety and distant transmission, and produces a high-resolution analogue-to-digital converter at low-cost.