射频电容式物位开关（限位开关）是一种采用了“射频技术”和“数码标定技术”的物位仪表，不仅避免了限位开关在使用中温漂大、不易标定，而且也克服电容式物位开关不能消除导电挂料影响的缺陷。
射频电容式物位开关是由传感器、电子单元组合的新型物位监测技术，当传感器安装于仓体上时，探极和仓壁分别相当于电容器的两个极板；由于被测物料的介电常数与空气不同，所以仓内物位发生变化时会引起探极对仓壁间的电容量发生变化，当该电容量大于用户的设定值时，限位开关内的继电器动作，输出一个开关量达到控制（或报警）的目的。
RF capacitance level switch （limit switch） is a kind of the "technology" and"calibration" digital level instrument, not only to avoid the limit switch in the use of temperature drift, not easy calibration, but also overcome the SCAP cannot eliminate the defect of the conductive coating nfluence.
RF capacitance level switch is composed of a new sensor, electronic unit
combination of monitoring technology, when the sensor is installed in thechamber body, probe and silo wall plate respectively two equivalent capacitors; because the material being measured dielectric constant and different air, so bin level changes will cause the probe capacitance to the silo wall between the change, when the electric capacity is greater than the user settings, limit relay switches in, output a switch to control （or alarm） purpose.
