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Germantown, Maryland

Tue Aug 14 2018

Capacitive sensors

  • Capacitive sensors

Capacitive sensors with high application potential

Capacitive sensors operate contactless, reactionless and wear-free. Both, electrically conductive and non-conductive materials are detected reliably. Capacitive sensors can thus be applied in systems in which inductive sensors would be inappropriate.

In addition to distance and position, capacitive sensors measure deflection, thickness, fi lling level, eccentricity, concentricity, deformation, wear and vibration.

The functional principle of capacitive sensors is based on the arrangement of two conductors (plates) separated by a dielectric (insulator). An electric field created through the potential diff erence between the two conductors is stored in the dielectric. The change of field strength (capacitance) in the dielectric is used as a measure. Non-conductive materials are detected through the change of field strength in the dielectric whereby a probe on the one hand and the ambient on the other hand represent the two conductors. Conductive materials are detected through the change of material as well as through the change of distance between the conductors.

The effective switching distances of capacitive sensors can vary considerably. A maximum switching distance is achieved with metallic objects. Reduction factors do not have to be observed as with conventional inductive sensors. With regard to other materials, the switching distance is reduced in dependance to the dielectric constant of the target object. The higher the value the higher the switching distance. The switching distance of nearly all capacitive sensors can be adjusted with a potentiometer.

Capacitive sensors are laid out for temperature ranges between -25 and +70 °C by default. Special version are also available for temperatures up to +100 °C.

Based on the novel technology, the closeup range suppression of TURCK sensors works also with conductive clingage. TURCK also off ers a solution for electromagnetic sensitivity. The product portfolio comprises sensors with EMC fi lter, making them insensitive to radiated and conducted HF interference and burst.

Capacitive sensors are available in cylinder and rectangular design. Alongside the standard plastic and metal versions, sensors enclosed in a Dyfl or housing are also available for extra protection against chemically aggressive environments.