Design of Self Compensated Non Contact Capacitive Sensors and Proficient Signal Conditioning Circuit for Multi Threshold Liquid Level Control -A Novel Approach

An innovative method for self-compensating capacitive sensor for multi threshold liquid level measurement is presented in this work. Presently it is a trend to design and develop non -contact type sensors for the measurement and control of liquid level, since chemicals in industry can corrode the sensors in contact used for the monitoring purpose. In practice the sensors are to be provided with compensation techniques to avoid the influence of environmental factors proving it more disadvantageous. This work comprises the design of non-contact type capacitive sensors, which employs self-compensation technique. The multi threshold level control concept involves control of liquid to different levels by increasing the number of electrodes. This paper also deals with a novel technique incorporated to design a precise and reliable signal conditioning circuit as per the demand of self -compensated capacitive sensors owing to their very low sensitivity. For practical experiments, a container with aluminium electrodes is fabricated and proficient SCC is developed. The values of the capacitances offered by the multi electrodes are measured and the corresponding voltage provided by SCC is interfaced to the microcontroller to control the liquid level for the given set point. Experimental results are depicted.