Working principle of liquid level transmitter

The working principle of the liquid level transmitter is that when two pressures of the measured medium are introduced into the high and low pressure chambers, they act on the isolation diaphragms on both sides of the delta element (i.e. the element), and are transmitted to both sides of the measuring diaphragm through the isolation diaphragms and the filling liquid inside the element.

The (float) liquid level transmitter is composed of a measuring diaphragm and an electrical capacitor on both sides of the insulating film. When the pressure on both sides is not consistent, it causes displacement of the measuring diaphragm, which is proportional to the pressure difference. Therefore, the capacitance on both sides is unequal. Through oscillation and demodulation, it is converted into a signal proportional to the pressure. The working principle of pressure transmitter and pressure transmitter is the same as that of differential pressure transmitter, except 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, which is used by the microprocessor to determine the input pressure value. The microprocessor controls the operation of the transmitter. Additionally, it linearizes the sensor. Reset the measurement range. Engineering unit conversion, damping, square root, sensor fine-tuning and other 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 digital signal from the microprocessor that has been calibrated, and these data can be modified using transmitter software. The data is stored in EEPROM and remains intact even when powered off.

The digital communication line provides a connection interface between the transmitter and external devices. This circuit detects the digital signal superimposed on the 4-20mA signal and transmits the required information through the circuit. The type of communication is frequency shift keying (FSK) technology and is based on the BeII202 standard.