Capacitive level gauge

feature

Multiple signal output forms, convenient for different system configurations;

Polytetrafluoroethylene electrode, resistant to strong corrosive liquids such as acid and alkali (except hydrofluoric acid and metallic sodium) and high temperature;

The measuring part only has one PTFE flexible wire or PTFE rod probe as a sensor, which has high reliability;

Can be used in high temperature and high pressure situations, and the measured values are not affected by the temperature, specific gravity, container shape, and pressure of the measured liquid;

Two line LED on-site display, no need for power supply, * solves the problem of LCD unable to display in dark environments;

Complete overcurrent, overvoltage, and power polarity protection.

structural principle

Capacitive liquid level measurementThe principle is that a capacitor is composed of a probe wire and a conductive liquid, where the metal core of the probe wire is one pole of the capacitor, the conductive liquid is the other pole, and high stability polytetrafluoroethylene is produced. As the liquid level changes, the area of the liquid surrounding the probe line also changes, resulting in a change in capacitance. According to the formula for concentric cylindrical capacitance, the relationship between liquid height and capacitance can be written:

C=Co+2πε/LogD/d＊h 式中：

Co: Distributed capacitance

ε: Dielectric constant of polytetrafluoroethylene

D: Probe outer diameter

d: Probe inner diameter

h: The height of the liquid immersed probe, as Co, ε, and D/d are fixed constants, is C=kh, meaning that the electrical capacity is only proportional to the height of the liquid immersed probe.

working principle

The UYB-2000 series transmitter is based on the principle of RF capacitance measurement, which reflects the change in capacitance by the height of the measured medium without a probe, and converts it into a corresponding 4-20mA current signal output through the circuit.

The pulse generator generates a frequency stable RF clock signal in the circuit, which is input into the phase shift circuit in the measurement module. The input and output of the phase shift circuit have a strict linear relationship with the measured capacitor, and after phase detection, amplification, and conversion into a current output signal.

Main technical parameters

Measurement range: 0.2-20m

Accuracy: Level 0.5

Exploration level temperature resistance: -40~250 ℃

Working pressure: -1MPa~2.5MPa

Tested medium: conductivity not less than 10^-3S/m amorphous conductive liquid

Power supply voltage: 24VDC (allowable range 15-35V)

Output signal: 4-20mADC two-wire system

Measurement adjustment range and zero shift: ≥ ± 30% FS

Model