INSTALLATION
16
SH4 BASE-STANDARD
Minimum distance from reflecting surface (D
SR
)
Reflecting surfaces placed near the light beams of the safety device (over, under or lat-
erally) can cause passive reflections. These reflections can affect the recognition of an
object inside the controlled area. Moreover, if the RX receiver detects a secondary beam
(reflected by the side-reflecting surface) the object might not be detected, even if the
object interrupts the main beam.
Figure 9: Distances from reflective surfaces
It is important to position the safety light curtain according to the minimum distance
from reflecting surfaces.
The minimum distance depends on:
• operating distance between emitter (TX) and receiver (RX);
• real aperture angle of ESPE (EAA); especially:
for ESPE Type 4 EAA = ±2.5°
In the diagrams shows the minimum distance from the reflecting surface (D
SR
), based
on the operating distance:
Figure 10: Minimum distance from reflective surface
The formula to get D
SR
is the following:
D
SR
(m) = 0.13 for operating distance < 3 m
D
SR
(m) = operating distance (m) x tan (2.5°) for operating distance ≥ 3 m
DANGEROUS ZONE
reflecting surface
reflecting surface
α
α
TX
RX
TX
RX
α
D
SR
m
m
0.2
3
10
20
Operating distance (D
OP
)
Reflective surface distance (D
SR
)
0.87
0.44
0.13
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