SG-BWS-T4
10
3.5.
Minimum distance from reflecting surfaces
Reflecting surfaces placed near the light beams of the safety device (over, under or laterally) can
cause passive reflections. These reflections can compromise the recognition of an object inside the
controlled area.
However, if the RX receiver detects a secondary beam (emitted again by the side-reflecting surface)
the object might not be detected, even if the object interrupts the main beam.
Fig. 7 Distance from reflecting surfaces
It is thus important to position the photocells according to the minimum distance D
sr
from reflecting
surfaces.
The minimum distance depends on:
operating distance between emitter (TX) and receiver (RX);
real opening angle of ESPE (EAA), especially:
for ESPE type 4 (S5-ST4, SL5-ST4, S300): EAA = 5° (
= ± 2.5°)
for ESPE type 2 (S5-ST2): EAA = 10° (
= ± 5°)
The formula to get D
sr
is the following:
{
D
sr
(m) = 0.15
for operat. dist. < 3 m
D
sr
(m) = 0.5 x operating distance (m) x tg (EAA)
for operat. dist.
3 m
