Proximity Switch

The PAC-30U and PDC-30 are RF capacitance-type level controls, which operate by detecting the electrical effect of the surrounding material such as air, plastic pellets or powders.


A radio frequency is applied to the proximity switch sensing region and is continually analyzed to determine the influence of the surrounding environment. Since all materials have dielectric constants and conductance values that are different from that of air, the resultant impedance seen by the radio frequency changes whenever material approaches or contacts the sensing region. This influence is measured within the circuitry and compared with the reference point set by the sensitivity adjustment, which determines how much influence must be present before the output changes.