Study of a non-contact opto-electronic liquid level transmitter for a conducting liquid using MZI technique

It is extremely important to accurately measure the liquid level as a process variable of a storage tank used by any plant. The transmitted electrical signal from a liquid level transducer or any other transducer to a remote indicator or controller may sometimes suffer from the measurement error due to its contamination with noise signal. This may be easily avoided by using modern optical fiber communication technique wherein we see the production of optical signal from the transducer output and its noise free communication through fiber-optic cable. In thie present paper, an opto-electronic liquid level transmission technique has been proposed for liquid which is conducting in nature and generally, collected in a storage tank. The electronic part of the transmitter unit consists of a modified capacitive transducer with a signal conditioner unit which produces an electrical DC output voltage which is linearly related with the level of the conducting liquid in the storage tank. This DC voltage is transformed into an optical signal with the help of Mach–Zehnder Interferometer (MZI) based electro- optic converter. Generated Optical signal may be dispatched to any location which is remote in nature by using fiber optic cable. Thus, various types of measurement error observed in the conventional capacitive level transmitter are minimized by using the proposed system. In the preset paper, a prototype model of the proposed system has been designed and developed to test its functionality. A good linear characteristic of the normalized optical output in support of the derived equations is observed.