Fiessler ULVT - Construction Requirements; Installation Without Additional Screening; Protection against Reaching over or under Barriers; Protection against Avoiding Barriers through Cascading or Additional Screening

4.3.1 Installation without additional screening
The light transmitter (a) (Fig. 17/1) and the light receiver (b)
form the light barrier (c). If the light beams are interrupted, e.g. by
a hand, a pilot circuit is opened and the closing action is
prevented / stopped. In the opposite example, it is not possible
to avoid the ULVT light barrier from the working side, which
means that additional screening is not required.
4.3.2 Protection against reaching under and over
4.3.3 Protection against walking behind through cascading or additional screening
4 Installation - Construction requirements
fig. 17/1 Installation without additional screening
fig 17/2a,b,c Protection against reaching under and over
≤ 75 mm
17/2.a
17/2.b 17/2.c
fig 17/3 Protection against walking behind through cascading of two light barriers
In cascading, varying form factors can be combined
(e.g. main sensor with 1100 mm protective field height
and succeeding sensor with 200 mm protective field).
Please refer to
chapter 8.
fig 17/4 Cascading of two safety light curtains
In order to prevent the walking behind the protective
field, the distance between the ULVT/BLVT safety light
barrier and the machine must be _< 75 mm.
In a normal working process (Fig. 17/2a), the operator inserts the workpiece when sitting down. Due to the over-
run period of the machine, the ULVT/BLVT safety light barrier (a) is mounted slightly in front of the hazardous
area (refer to chapter 4.2). However, the light barrier height selected here leaves an unprotected gap at the top of
the light barrier. Fig. 17/2b shows how reaching over the light barrier can lead to an accident. The proper
rectification of this problem is illustrated in Fig. 172/2c, where a ULVT safety light barrier with a larger protective
field height has been attached.
If the distance between the vertical ULVT/BLVT
safety light barrier and the machine needs to be
greater than 75 mm (e.g. in order to maintain
the safe distance to the hazardous area), the
possibility of walking behind the protective field must be
eliminated through an additional ULVT safety light
barrier and/or cascading of two light barriers (Fig. 17/3 and
17/4) or a protective bar.
wrong!
correct!
correct!
FIESSLER
E L E K T R O N I K
wrong!
mm
17
Fiessler Elektronik GmbH & Co. KG
Doku Nr. 958 Stand 22.01.2018 RK
Phone: +49 (0) 711 / 91 96 97-0 Internet: http://www.fiessler.de
Fax : +49 (0) 711 / 91 96 97-50 eMail: info@fiessler.de