Problems with radio frequency admittance level gauges

Some people ask what “hang material” is

See http://bbs.hcbbs.com/viewthread.php?tid=339823, page 3, for the definition of material hanging.

RF admittance level gauges utilize advanced RF admittance principles instead of the traditional pure capacitance principle, enabling them to perform reliable measurements even under extremely harsh conditions – whether it is liquids, slurries, particles, or interfaces. They are not affected by factors such as deposits on the surface, temperature, pressure, density, or even changes in chemical properties. Since their measurement is based on the dielectric constant, which exists in all materials, they can measure almost any type of material level. In principle, the electrical properties of any material are manifested through its conductivity and insulation resistance. Conductivity refers to the current that flows through a unit volume of material when a certain voltage is applied to it, while insulation resistance relates to the current that flows through that material per unit of time. The equivalent circuit for these electrical properties is as follows: Ro represents the direct-current resistance of the material, and Co represents its inherent capacitance. Ro∥Co. When a high-frequency voltage is applied to this equivalent circuit, a constant current flows through it during each alternating current cycle; the value of this current is given by: I = current flowing through the equivalent circuit, V = effective value of the high-frequency voltage. Based on these characteristics, the following mathematical model for a detection circuit can be established: Uo = effective value of the high-frequency voltage to be measured, w = angular frequency, R = sampling resistor. Since the distance between the detection electrode and the ground electrode in continuous measurement instruments is fixed, the impedance and capacitive reactance between electrodes per unit length are also fixed; thus, the admittance characteristic of the material per unit length is a linear constant. Conductance = the reciprocal of the resistance value = 1/R. Susceptance = the reciprocal of the capacitive reactance value = 2πfc = WC. The point-control switch is also designed based on the fact that the impedance of the probe changes significantly when it is in air or within a material. Working principle: The radio frequency admittance switch emits a certain radio frequency signal at the probe, thereby analyzing and determining changes in the liquid level inside the container. As the material being examined changes, the frequency of radio waves also changes. The probe and the container wall form a capacitor with a fixed spacing, while the insulating material of the probe and the surrounding air serve as the insulating medium. When air is replaced by other media, the capacitance formed between the probe and the container wall changes, and this change causes a variation in the radio frequency applied to the probe. This change is detected by the internal circuits of the switch, and its amount of change is determined by comparing it with the set value

Thank you to all the fellow sailors; I’ve learned so much and I’m very touched