陶瓷泥料水分电容传感器电路分析

泥料水分快速测定仪中使用的电容传感器主要根据水的介电常数很大，物料本身的介电常数很小这一特点，当物料的含水率发生变化时会引起传感电容的变化。产生这种变化的真正的原因不是料或水的介电常数发生了变化．而是因为物料中的水和料部分的体积百分比发生了变化，探头中水和料形成的电容可分别表示为Cs＝f（B）和CL＝f（1－B），B为水分的体积百分比。传感电容实际上由Cx＝Cs＋CL共同组成，但进一步分析可以发现，泥料的传感电容是由一个固定不变的电容CLo（由料的介电常数所决定）和一个随物料中水分体积百分比B而变化的电容CY并联组成，即Cx＝CY＋CLo,而CY＝0．0884B因此泥料的体积百分比B与传感电容CY呈线性关系，可用数学模型B＝bCY＝bCX＋bCLo来表示。

CIRCUIT ANALYSIS OF CAPACITANCE-SENSORS FOR DETERMINING WATER CONTENT IN CERAMIC BODY PASTE

As a part of the rapid moisture teller to determine water content in body paste, capacitance sensors are usedmainly in the light of dielectric constant large in water and small in material itself. As water content in the pastechanges, it will cause a change in sensitive capacitance. In fact, the reason is not the change taking place in dielectricconstant of material or water. It is the volume proportion of water to material that causes the change.The capacitance formed by water and material can be expressed as Cs = f(B) and CL = f(1 - B) respectively, Brepresenting the percentage of water content in volume. Sensitive capacitance Cx actually consists of Cs and CL(Cx = Cs CL). Further analysis shows that sensitive capacitance of the paste consists of an unchanging capacitance CLo(determined by dielectric constant of material) and a capacitance CR changing with the volume percentage B of watercontent in the paste, that is: Cx = CY CLo. When CY = 0.0884 B, B has a linear relation with sensitivecapacitance, which can be expressed with a maths model B = bCy = bCX bCLo.