Rockwell Automation Publication 450L-UM001D-EN-P - December 2019 79
Installation and Wiring Chapter 6
Figure 45 - Terms to Help Define Safety Distance to Avoid the Possibility of Standing between the
Protective Field and the Point of Operation
Mount Multiple 450L GuardShield Safety Light Curtains
When two or more 450L safety light curtain pairs are mounted closely, the
following possibilities can happen:
1. Optical interference: The receiver of one pair “sees” sporadically infrared
light from the transmitter of another pair. Optical interference between
neighboring 450L safety light curtain systems can affect light curtain
system reliability by sporadic switching offs of the OSSDs.
2. Optical crosstalk (see Figure 47 on page 80
): The receiver of one pair
communicates continuously with the transmitter of another pair. Optical
crosstalk between neighboring 450L safety light curtain systems cause
holes in the protective field and is therefore an unsafe installation. Optical
crosstalk can only occur if:
a. Both systems have the same resolution and the same height of the
protective field.
b. The height of the protective field is smaller than the minimum
separation distance S provided in Table 14 on page 50
.
c. The space between both pairs is smaller than the minimum separation
distance S provided in Table 14 on page 50
.
IMPORTANT Confirm that an operator is not able to stand between the protective field
and the point of operation (hazard). EN ISO 13855 requires a minimum
distance X at an installation height of 300 mm (11.9in.). Check EN ISO 13855
for other installation heights.
Safety
Distance Ds
Middle of Depth
of Protective Field
Point of Operation
Top of Tool
Machine
Stop Time
Middle of Depth
of Protective Field
Protective Height
X
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