| 摘要 |
PURPOSE: To measure a stirring and granulating process at high precision and stably provide a granulated material with excellent fluidity by measuring a microscopic load alteration in by carrying out frequency analysis for electric power of an induction motor. CONSTITUTION: The electric power of an induction motor for a stirring and granulating apparatus is measured by an electric wattmeter 2, the output of the meter is inputted to an FFR analyzer 3, and after d.c. components are removed, frequency is analyzed by Fourier transformation. Then, analysis is carried out by the FFT analyzer 3 compute the electric power difference Δp1 base on the alteration of phase difference and electric power difference Δp2 proportional to the difference of the phase difference. Since the Δp1 can be measured from the intensity of the components with the frequency about the rotational frequency of a load, the Δp1 can be quantified based on the overall power spectrum in a specified region. Since the Δp2 is components with frequency two times as high as that of the electric power source, Δp2 can be quantified based on power spectrum with 120Hz if the electric power source frequency is 60Hz. The quantified values are collected by a personal computer 4 and based on the set values obtained from past experiment values, control and abnormality diagnosis are carried out. |
