Abstract
The dielectric method for accurate and rapid measurement of moisture content in granular materials is described in this paper. The different points from conventional usual method are as follows:
1) Substitution method, especialy for small capacitance circuit, has no effect of the parallel resistance of specimens using large sized electrodes.
2) The highest sensitivity of the measuring circuit is about 17μA/10-3 pF on a microammeter with a full scale range of 100μA. The circuit is not influenced by the parallel resistance value of specimens by several tens kΩ and over.
A construction and a capacitance measuring method of the concentric circle type grid electrodes are investigated. The penetrated height of the electrical field in the electrode is defined experimentaly. The dielectric property of wheat and sugar are measured by various electrodes.
The most important problem for dielectric measurement determining moisture content in grain is the dispersion of measuring values of capacitance. The dispersion is disccused on insertion of specimens and the size of electrodes. The results of experiments came out as expected.
Finally, moisture content in wheat, granulated sugar and sugar (first-class, second-class) measured by this method are described.
