Fotoelektrik Pauly – Light barriers
E_52692 Ref. 2019-29
13/24
Fotoelektrik Pauly GmbH, Wahrbrink 6, D-59368 Werne, T: +49 2389/402 27-70, F: +49 2389/402 27-77
http://www.fotoelektrik-pauly.de, eMail: info@fotoelektrik-pauly.de
4.4 Pollution control function
4.4.1 Principle
Primarily, the photoelectric barrier monitors itself continuously, independent of the travel
movements. The light signal level, which is sent from the external test unit through the receiver
lens, is evaluated at all times. The weakening of a specific signal level due to contamination of this
test device (see also example in section 4.4.2) leads initially to a pollution warning signal. If the
pollution is not eliminated, and with the increasing pollution, the specific function signal is further
weakened then this leads to the stopping of the travel movement and the safety-related switching
relays is switched off.
In a secondary effect, the reflector signal level is evaluated with active reflector detection. The
weakening of a specific signal level here also leads to a pollution warning signal.
The pollution on the external test unit of the light barrier will be much more sensitively evaluated
than the pollution on the reflector.
The pollution warning signal is displayed with the
“VK-relay”. The triggered relay means that there
is a pollution which must be eliminated as soon as possible, where the location of the pollution
should be derived from the circuit states of the VK-relay and the states of the safety-related relays
(see also section 4.4.3).
4.4.2 Pollution example
Dust precipitation on an external test unit which can
lead to a Pollution warning signal and/or blocking of
the system.
In case of cleaning of the reflex light barrier system,
the pollution of lenses, external test unit and the
reflector are to be particularly eliminated
For the cleaning procedure, please note in addition
the chapter 5
on “Maintenance and cleaning” of the
respective operating instructions.
Fig.: 4.4.2
An appropriate warning system should be triggered by the pollution warning relay to
provide timely detection and removal of pollution to maintain system availability.
