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Unformatted text preview: urements. Fig. 16.4.1: Level sensing by detecting the filling mound and emptying depression in granular material Furthermore, it should be noted that the switching distance to be attained with
capacitive proximity sensors heavily depends on the water content of bulk materials.
Damp bulk materials result in a greater switching distance than dry materials. Exercise 5.2 Environmental effects on capacitive proximity sensors
A capacitive proximity sensor measures a change of capacitance in the active zone
and evaluates this change. If humidity settles on the proximity sensor housing (dew,
fog), this can lead to an error signal. Because water has a high dielectricity constant
(ε = 81), small droplets of moisture are sufficient to interfere with the proximity
sensor. Capacitive proximity sensors are available which can compensate the effects
of humidity by means of an auxiliary electrode. © Festo Didactic GmbH & Co. KG • FP 1110 259 16. Solutions Exercise 5.3 Detection of cardboard boxes
Because the capacitance change...
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- Spring '12