射頻電容式物位開關（限位開關）是一種采用了“射頻技術”和“數碼標定技術”的物位儀表，不僅避免了限位開關在使用中溫漂大、不易標定，而且也克服電容式物位開關不能消除導電掛料影響的缺陷。

射頻電容式物位開關是由傳感器、電子單元組合的新型物位監測技術，當傳感器安裝于倉體上時，探極和倉壁分別相當于電容器的兩個極板；由于被測物料的介電常數與空氣不同，所以倉內物位發生變化時會引起探極對倉壁間的電容量發生變化，當該電容量大于用戶的設定值時，限位開關內的繼電器動作，輸出一個開關量達到控制（或報警）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.