The whole system of intelligent frequency conversion constant pressure water supply energy-saving control cabinet is composed of four pumps, one inverter, one PLC and PID (PLC is an electronic device designed for digital operation in industrial environment), one pressure transmitter and several auxiliary components.
PLC uses a memorizer that can be programmed to store the instructions to perform logical operations, sequential operations, timing, counting and arithmetic operations, and can control various types of machinery or production processes through digital or analog inputs and outputs. PLC controller and its related peripherals ought to be easy to form a whole with the industrial control system, easy to expand its functions and the principle of design. At present, the level of industrial automation has become an important symbol to measure the level of modernization of various industries. At the same time, the development of control theory has gone through three stages: classical control theory, modern control theory and intelligent control theory. Typical examples of intelligent control are fuzzy automatic washing machines and so on. Automatic control systems can be divided into open-loop control systems and closed-loop control systems.
A control system includes a controller, sensors, transmitters, actuators, input, and output interfaces. The output of the controller is added to the controlled system through the output interface and the actuator; the controlled quantity is sent to the controller through the input interface of the control system, via the sensor and transmitter. The different control system has different sensor, transmitter, actuator. For example, pressure control systems need to use pressure sensors. The sensor for electric heating control system is a temperature sensor. At present, PID control and its controller or intelligent PID controller (instrumentation) has been abundant, the product has been widely used in engineering practice, there are a variety of PID controller products, major companies have developed intelligent regulator with PID parameters self-tuning function, where the automatic adjustment of PID controller parameters is achieved through intelligent adjustment or self-correction and adaptive algorithms.
There are pressure, temperature, flow, level controllers using PID control, plc controller that can achieve PID control functions, and PC systems that can realize PID control, etc.