Level detection with Capacitive level switches
In addition to capacitive level switches, there is another type of sensor, the RF level detector, which is also based on the operating principle of a capacitor. The two types therefore do not differ in the way the limit level is determined, but rather in their mechanical design. As a result, they also cover different areas of application.
RF level detectors measure the capacitance between their probe (active electrode) and a reference electrode, which can be a metallic container wall, for example. If the probe is covered with material, this leads to a change in capacitance, which is detected by the electronics and output as a switching signal (relay or transistor). The dimensions of the capacitor can be variably changed over the probe length, which leads to an increase in sensitivity. Because of this variability, RF sensors must be calibrated after installation.
Capacitive level detectors do not require a metallic vessel wall for measurement. The two conductive electrodes required for a reliable measurement result are completely integrated into the probe. This simplifies commissioning, as no calibration is required after installation.