Capacitance Level Indicator: Utilizes the capacitance formed between the sensing probe and the metallic vessel wall. A high frequency sine-wave is applied between the probe and the vessel wall.
A change of the medium level will induce a change in the current of the applied sine wave.
From Z=1/2pfc, when the capacitance in the vessel increase, impedance will decrease and current will increase. Vice-versa, when the capacitance in the vessel is small, the impedance will increase and current will decrease accordingly.