SICK WEU26-3 - Page 15

Operating Instructions Chapter 4
WSU/WEU263
8013338/YTA4/2016-03-24 © SICK AG • Industrial Safety Systems • Germany • All rights reserved 15
Subject to change without notice
Mounting
1.100
700
300
How to calculate the safety distance S according to EN ISO 13855 and EN ISO 13857:
The following calculation shows an example calculation of the safety distance. Depending
on the application and the ambient conditions, a different calculation may be necessary.
 First, calculate S using the following formula:
S = K × T + C [mm]
Where ...
T = Stopping/run-down time of the machine + response time of the WSU/WEU26@3
devices after light path interruption [s]
S = Safety distance [mm]
K = Approach speed 1.6 [m/s]
C = Depending on the number of beams (1, 2, 3 or 4), see Tab. 5
Number of beams 1 2 3 4
Height of the beams above the floor
[mm]
750 400
900
300
700
1,100
300
600
900
1,200
C 1,200 850 850 850
Example:
Access guarding with two beams C = 850 mm
Stopping/run-down time of the machine = 290 ms
Response time after light path interruption = 22 ms
Approach speed = 1.6 m/s
T = 290 ms + 22 ms = 312 ms = 0.31 s
S = 1,600 × 0.31 + 850 = 1,346 mm
Fig.
5
:
Safety distance S to
the light beam
Note
Tab.
5
:
Height of the beams
above the floor
Hazardous
p
oint
WSU/WEU26@3
Safety distance S (D
S
)