Experimental Study of Instrumentation and Control Devices on Water Level for On Off with Programmable Logic Controller (PLC)

Abstract

Liquid level control is an important factor in various industrial processes such as water treatment, chemical, pharmaceutical, and manufacturing to ensure efficiency, safety, and product quality. One commonly used technology is the Programmable Logic Controller (PLC) due to its flexibility, reliability, and ease of integration with automation systems. This research aims to design, build, and test a PLC-based liquid level control and instrumentation tool with an on-off control method using electrode sensors. The research process includes literature study, system design, component selection, assembly, PLC programming using ladder diagrams, and system performance testing. The developed device consists of a main tank, a pump, electrode sensors at three points (high, medium, low), a PLC input-output circuit, and a relay driver. The testing was carried out in two stages: first, direct sensor testing without a PLC to determine accuracy and response time; second, integrated system testing to evaluate automatic control performance. The results show that the electrode sensor is able to detect liquid levels with 100% accuracy in clean water with a response time of less than 1 second. The integrated system with PLC works according to the programmed on-off logic, is able to maintain the liquid level at the desired limit without manual intervention, and operates stably in repeated tests without sensor reading errors or control failures. The conclusion of this study is that the PLC-based liquid level instrumentation and control system with electrode sensors is proven to be effective, responsive, and reliable, and has the potential to be applied to small to medium-scale industries with minimal modifications, and can be further developed for more complex controls such as Proportional-Integral-Derivative (PID) or integration with Supervisory Control and Data Acquisition (SCADA).