SICK LE20 Instrucciones De Operación página 292

Chapter 2
WARNING
2 9 2
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Safety notes
controls) must be prevented, as it may reduce the operability of
single-beam photoelectric safety switches.
3 . The number of beams from the sender and receiver as well as
the distance between the beams must correspond.
Single-beam photoelectric safety switches - mutual
interference
When several pairs of single-beam photoelectric safety switches
are used, the aperture angle of the sensors MUST be observed, to
prevent mutual interference.
If the senders are mounted on one side only, the light beams must
not overlap on the receiver side such that the light beam of one
sender reaches two receivers.
In case of reciprocal installation of the senders and receivers (see
Fig. 2-2), it must be ensured that the light beam from sender S1
cannot be received by receiver R3 and that the light beam from
sender S3 cannot be received by receiver R1.
Fig. 2-2: Installation in order to avoid mutual optical interference
4. Reflective surfaces, which are placed or attached within the
sending and receiving beam path, can lead to reflection and
Operating Instructions
Safety Evaluation Unit LE 20
8 008 685/Q913/2007-05-21