Capacitive level switch know as capacitive point level detection also, the sensor and vessel form the two electrodes of a capacitor. Any capacitance change caused by a level change is converted into a switching signal.
When material is empty, electrical status of detecting electrode and grounding electrode is: resistance (Ro) is infinite, and capacitance (Co) will be specific capacitance value determined by installation status.
When the material is applied into a vessel, the electrode is filled (full status), resistance value and capacitance value between detecting electrode and grounding electrode changes to Rs and Cs. The switch captures this change and outputs.
