MODELING OF A POTENTIOMETRIC LEVEL SENSOR AND ERROR ASSESSMENT

Abstract

This article discusses the principle of operation of a potentiometric level meter for measuring the level of an electrically conductive liquid in a vessel. An electrically conductive liquid is measured by an indirect method in a grounded tank. The device consists of a sensor with low electrical resistance, an alternator, a metal vessel wall and a small signal amplifier.The nonlinearity of the transfer function does not allow the measured values of the sensor to be used without preliminary linearization. Therefore, it is necessary to develop a sensor model in an electrically conductive liquid and determine factors affecting the accuracy of level measurement.To assess the accuracy of measurements, the article presents a model of the electric field inside the electrolyte created by a sensor of a potentiometric level meter in a vessel with a cylindrical wall. Numerical methods based on the finite element method are used to calculate potentials and currents inside the electrolyte. The finite element model and the finite element grid allows to consider the transfer of potentials between finite elements.It is shown that the level measurement error in a potentiometric level meter has an unacceptable value and depends on the liquid level and on the location of the level meter.Based on the obtained model, the factors influencing the measured value of the liquid level were determined and the absolute and relative measurement errors were calculated. Further steps have also been identified to improve the accuracy of measuring the level gauge.