SB RF-Capacitance / Admittance Level Switch

Principle

In order to eliminate false alarm given due to  medium with high viscosity sticking onto the probe , a special material acting as an insulation  electrode have been added in between the active section and the grounding section.
As shown in the diagram, sensing probe always experience medium clogging on it and thereby produces a capacitance and resistance between the 3 parts. Since the electric field between the active section and the guard section is round shaped, there will be no current passing through the medium between the electrodes.
The Admittance level switch uses this principle, to add a guard section between the active section and the grounding section to block the admittance current to reach the vessel wall from the medium between the active section and grounded  electrode. Although there would be a small amount of admittance current between the guard section and the active section, the circuit would not take this current value into account. Due to the guard section, only the admittance current change between the active section and the tank wall will be detected by the circuit, thus only when the sensing probe is in contact with the medium will there be a precise signal.