Measurement principle of RF admittance level meter

Traditional capacitive level gauges increase as the level rises, the material covers the probe, the capacitance between the probe and the medium in the circuit (in the case of conductive materials) or the capacitance between the probe and the wall (insulation material occasions) increases. . Since the change of the level leads to the unbalance of the capacitor bridge, the change of the capacitance value depends on the dielectric constant of the measured material. Then through the signal detection, amplification, and finally output the corresponding signal. However, capacitive level meters have some drawbacks, especially when the probe has a hanging material that can seriously affect the measurement results.

RF admittance measurement technology is a level measurement technology with unique advantages. Although similar to the concept of general capacitive measurement technology, radio frequency admittance technology incorporates a Driving-Shield circuit and a chopper circuit in the electronic unit, thus enabling independent measurement of impedance and capacitive reactance. Calculated by physical laws, the impedance of any hanging material is equal to the capacitive reactance, so the influence produced by the hanging material can be measured and eliminated from the total output by the phase shift of the oscillating circuit.

The probe of the RF admittance product is installed in a storage tank, and the change of the RF signal caused by the level change is obtained through the probe.

The Driving-Shield end of the probe prevents the RF current from forming through the loop and ensures meter accuracy.

The radio frequency admittance technology has high accuracy of measurement results and is not affected by the probe hanging material. It is the most widely used measurement technology in the field. From low temperature -100°C to high temperature 800°C, from vacuum to 6.3 MPa for high pressure applications, from ultra-short range to 120 meters for ultra-high-volume applications, it can be applied normally and can be applied to different types of materials.