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8 007 487/ 10-10-99 Technical Description • LGT © SICK AG • Safety Systems • Germany • All rights reserved
right
wrong
right
Light beam
interrupted
Central beam
R
R
R
R
R
R
S
S
S
S
S
S
LGTS
LGTE
4º
4º
a
Boundary of
hazardous site
Reflective part
(e.g. container)
a (mm)
500
400
300
200
100
50
0
1 2 3 4 5 6
LGTS
LGTE
8˚
a
a
8˚
RW (m)
Fig. 8. Correct mounting and alignment. No reflection. The obstacle is clearly detected.
Fig. 9. Distance a as a function of the range RW
Fig. 10. Mounting two LGT systems in series
5.1.2 Distance to Reflective
Surfaces
Reflective surfaces located, placed
or mounted within the transmis-
sion and reception lobe can deflect
the light beams and may prevent an
object from being detected
(Fig. 8).
For this reason, a minimum dis-
tance
a
between reflective objects
and the optical axis (straight-line
connection LGTS/E) must be ob-
served. The distance
a
depends on
the respective distance between
the sender and receiver and on the
alignment of the units (Fig. 9).
5.1.3 Multiple safeguarding
When using two LGT systems
(pairs), mutual interference must
be avoided between each safe-
guarded area. Since the light beams
diverge, the cross-section of the
beams increases proportionately to
the distance between the LGTS
and LGTE. The light beam must
only be received by the corre-
sponding LGTE. In order to pre-
vent mutual interference between
LGTs arranged in sequence, the
alignment must be taken into ac-
count when installing the units
(Fig. 10).
Direction of
approach