Intelligent pressure transmitter is a pressure parameter monitoring device widely used in the process of industrial production control, and is used in many fields such as petrochemical industry, water conservancy and hydropower, railway transportation and so on. It can be used to continuously and accurately measure the pressure, differential pressure, absolute pressure, liquid level and other process parameters of gas, liquid and steam, and convert the measured signal into 4~20mA DC standard signal and HART signal output through its conversion function , for other control and regulation instruments and DCS distributed control system.

Because the intelligent pressure transmitter has the advantages of high precision, small temperature drift, good long-term stability, and rich functions, it is a key component for modernization and automation of industrial production. Therefore, it is particularly important to ensure the reliability of the intelligent pressure transmitter, and its reliability has a significant impact on the trouble-free operation of the entire system production process.

The working principle of the intelligent pressure transmitter is shown in Figure 1. Figure 1 mainly includes delta chamber sensor, sensor excitation and signal conditioning circuit, A/D conversion circuit, microprocessor, D/A conversion circuit, HART communication, display circuit, etc. Among them, the delta chamber sensor is the key element. Since the temperature change of the sensor body needs to be detected, a high-precision temperature sensor is embedded in the positive pressure end of the delta chamber, which constitutes a pressure-temperature composite sensor. When the external pressure acts on the isolation diaphragm of the delta chamber, the change of pressure can be transmitted to the measuring diaphragm located in the center through the transmission of the filling silicone oil, causing it to produce a small displacement (maximum 0.08mm), which The displacement distance is proportional to the pressure applied. The displacement change of the central measuring diaphragm will cause the capacitance of the two fixed capacitor plates to change, and the change of the pressure can be detected through the change of the capacitance.