The Design Of Capacitance Level Meter

Level meter is an indispensable instrument and safety accessories in industrial measurement. Level meter is used widely in petroleum, chemical, pharmaceutical and other industries. The capacitive level meter is used widely because of its low cost, long service life. But its own defects, such as temperature-drift and parasitic capacitance seriously, limits the improvement of its measuring precision.This subject is to design a capacitive level meter which overcome temperature-drift and parasitic capacitance of traditional capacitive level meter. Coming to adapt to the dielectric constant automatically, overcoming temperature-drift of the liquid and circuit components and reducing the effect of parasitic capacitance. First of all, analyzing the advantages and disadvantages of traditional capacitive liquid level meter based on the research of the principle of traditional capacitive level meter. Designing a new type of capacitive sensor which aiming at the problems of the traditional capacitive liquid level meter and carriying on the detailed formula deduction.Then putting forward the overall design of the hardware circuit diagram and dividing each circuit module(e.g., signal transformation module, the period measurement module, single-chip microcomputer and peripheral circuit module). Clearing the specific function and component unit circuit of each circuit module. Analysising the principle and function of realization of each unit circuit one by one. Then introducing the overall structure of software and the overall workflow carefully, And listing programming implementation of each subroutine。Finally doing array experiments, acquiring a lot of experimental data and analyzing the experimental data.According to different installation, this topic designs separate capacitance sensors and integrated capacitive sensor. And doing array experiments with two sets of sensor. Analysis of a large number of experimental data show that the capacitive level meter can work stably and reliably,the absolute error range in about 3 mm in the case of measuring range of 1 m,the capacitive level meter can meet the requirements of 0.5 on the richter scale precision. Through subsequent perfect optimization(such as sensors more precision machining) should be able to obtain higher measurement accuracy.