The principle of operation of radio frequency conductivity level switches is based on radio frequency (RF) capacitance technology.
A radio frequency is applied to the probe and the influence caused by the surrounding environment is determined by continuous analysis. Because all materials have a dielectric constant and their conductivity are different from air, the total impedance reflected by the small capacitance shift changes when the probe is in contact with the material. Because the energized probe and the vessel wall constitute the two pole plates of the capacitor, the insulator of the probe and the surrounding air become dielectric materials, and the capacitive effect is enhanced when the air (whose dielectric constant is 1.0) is replaced by any other material (dielectric constant > 1). Thus, the impedance of the application is changed. That is, the change in capacitance value causes a change in impedance. This effect is measured by the circuit and then compared to the reference reference frame established by the sensitivity setting (circuit). The correct setting of the RF Admittance Level Switch sensitivity affects the correct change in sensor output. The probe's Nul1-KoTeTM circuitry allows the measurement circuit to ignore material buildup on the probe that would otherwise cause a sensitivity failure. The Nul1-KoTeTM circuit is excited with the same radio frequency potential as that applied to the sensing probe. Since the current cannot flow at the same potential, the Nul1-KoTeTM circuit isolates the current flow that normally flows from the energized probe through the stacked material to the vessel wall. This way the material around the energized probe is measured, not the stacked material.