9
Single beam protection
When risk analysis permits the use of a single beam to detect a person approaching the
hazardous area standing up and intercepting the beam (fig. 3) with his/her body, the
minimum safety distance, S, is determined on the basis of the following formula:
S = 1600(tb + tu + t1) + 1200
In this case we recommend arranging the equipment so that the beam runs parallel to
the reference plane, G, at a height H=750mm (fig. 3).
When using a single beam protection it is necessary to take into account the risk of a
person intruding into the hazardous area without intercepting the beam.
Figure 3
Figure 4
Double beam protection
Through the use of two overlapping MINERVA photocells with the two beams aligned
one on top of the other it proves possible to create a double beam protection set-up.
In this case, the minimum safety distance must be calculated from the following formula:
S = 1600(tb + tu + t1) + 850
The distances H of the beams from the reference plane G are 400mm and 900mm,
respectively (fig. 4).
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