Since the end of the 20. century, the industry has been focusing on production system automation and trying to minimize human the intervention. This is how the Programmable Logic Controllers were born.The thesis will introduce a PLC program which is currently running in a newly built factory. The program is responsible for the control of the cooling system of the supply transformators of the factory, precisely the high, middle and low voltage rooms. The program has to be precisely fit into an already completed program structure. This structure ensures the easy readability and transparency of the completed program. The program structure will be introduced in details at the beginning of the thesis. Furthermore, every equipment which was used under the project will be described, like digital and analog controlled dampers, frequency changers and direct motors. After the presentation of the PLC program, the thesis will introduce the programming of the user interface. The visualization of the automation system has to be equal to the drawings which were given by the client at the beginning of the project.