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Unformatted text preview: n the capacity margin of
the proximity sensor; see chapter 6.1 for further details. © Festo Didactic GmbH & Co. KG • FP 1110 261 16. Solutions Exercise 6.2 Selection of optical proximity sensors
If insufficient mounting space is available at the point where the proximity sensor is
to be employed for object detection, optical proximity sensors with fibre-optic cables
are particularly suitable. Because of the small dimensions of the sensor heads, fibreoptic cables can be used in inaccessible places.
The choice of fibre-optic cable material has to be made on the basis of
environmental conditions. Whilst polymer fibre-optic cables generally can only be
used in a temperature range of -25 – +70 °C, these values range between
-20 –+200 °C for glass fibre-optic cables. Special designs are available for different
temperature ranges. Resistance to chemicals also has to be taken into account when
selecting fibre-optic cables.
An important advantage of this arrangement is that the actual proximity sensor with
its electrical connections does not have to be installed near the point...
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