The working principle and maintenance of pressure transmitter

The two pressures of the measured medium of the pressure transmitter enter the high and low pressure chambers, which act on the isolation diaphragms on both sides of the element (ie the sensitive element), and are transmitted to the measurement diaphragm through the isolation sheet and the filling liquid in the element On both sides. The electrodes on the measuring diaphragm and the insulating plates on both sides each form a capacitor. When the pressures on both sides are inconsistent, the measuring diaphragm will be displaced. The displacement and the pressure of the measured medium of the pressure transmitter will enter the high and low pressure chambers and act on the two pressure chambers of the delta element (ie the sensitive element). On the side isolating diaphragm, the filling liquid in the isolating plate and the component is transferred to both sides of the measuring diaphragm. The electrodes on the measuring diaphragm and the insulating plates on both sides each form a capacitor. When the pressures on both sides are inconsistent, the measurement diaphragm will be displaced. The displacement is proportional to the pressure difference. Therefore, the capacitances on both sides are not equal. Through the oscillation and demodulation link, it is converted into a signal proportional to the pressure. The working principle of pressure transmitter and absolute pressure transmitter is the same as that of differential pressure transmitter, but the difference is that the pressure in the low-pressure chamber is atmospheric pressure or vacuum. The A/D converter converts the current of the demodulator into a digital signal, the value of which is used by the microprocessor to determine the input pressure value. The microprocessor controls the work of the transmitter. In addition, it performs sensor linearization. Reset the measurement range. Engineering unit conversion, damping, prescribing, and sensor fine-tuning calculations, as well as diagnosis and digital communication. This microprocessor has 16-byte program RAM and three 16-bit counters, one of which performs A/D conversion. The D/A converter fine-tunes the data from the calibrated digital signal from the microprocessor, and these data can be modified by the transmitter software. The data is stored in the EEPROM, even if the power is off, it is kept intact. The digital communication line provides a connection interface for the transmitter with external equipment (such as Huahai intelligent communicator or control system using HART protocol). This circuit detects the digital signal superimposed on the 4-20mA signal and transmits the required information through the loop. The type of communication is frequency shift keying FSK technology and is based on the BeII202 standard.