Abstract:Whether the interlocking logic of thermal control protection and the setting of constant value are scientific or not, will be the guarantee of safe and reliable operation of equipment in thermal power generating units. Analyzing the situation of cleaning up logic and checking constant value, and summarizing the common problems of them for different type, different capacity, and different control system of units, especially analyzing the situation that junk logic will lead to high load rate of controller; and that the logic and constant value modify arbitrarily; and that related rules and regulations are poorly enforced; and that the design of temperature and water level logic have holes; and other safety problems. This paper puts forward specific measures to solve those problems, finds hidden dangers timely to improve the reliability of thermal control system, and prompt thermal power generating units security and stability operation, so cleaning up logic and checking constant value have important significance and urgent needs.