SICK deTec4 Core Operating Instructions Manual page 20

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PROJECT PLANNING
20 O P E R A T I N G I N S T R U C T I O N S | deTec4 Core
Calculation example of the minimum distance S according to ISO 13855
The example shows the calculation of the minimum distance for orthogonal approach
to the protective field. Depending on the application and the ambient conditions (e.g., a
protective field parallel or at an arbitrary angle to the direction of approach or an indi‐
rect approach), a different calculation may be required.
1. First, calculate S using the following formula:
S = 2,000 mm/s × T + 8 × (d – 14 mm)
Where:
S = minimum distance in millimeters (mm)
°
T = machine stopping time + response time of the protective device after
°
interruption in the light path in seconds (s)
d = resolution of the safety light curtain in millimeters (mm)
°
The reach/approach speed is already included in the formula.
2. If the result S is ≤ 500 mm, then use the determined value as the minimum dis‐
tance.
3. If the result S is > 500 mm, then recalculate S as follows:
S = 1,600 mm/s × T + 8 × (d – 14 mm)
4. If the new value S is > 500 mm, then use the newly determined value as the mini‐
mum distance.
5. If the new value S is ≤ 500 mm, then use 500 mm.
Example calculation
Machine stopping time = 290 ms
Response time after interruption of the light path = 30 ms
Resolution of the safety light curtain = 14 mm
T = 290 ms + 30 ms = 320 ms = 0.32 s
S = 2,000 mm/s × 0.32 s + 8 × (14 mm – 14 mm) = 640 mm
S > 500 mm, therefore:
S = 1,600 mm/s × 0.32 s + 8 × (14 mm – 14 mm) = 512 mm
Taking reaching over into account
If access to the hazardous area cannot be ruled out by reaching over a vertical protec‐
tive field, the height of the protective field and minimum distance of the electro-sensi‐
tive protective device must be determined. This is done by comparing the calculated
values based on the possible detection of limbs or body parts with the values resulting
from reaching over the protective field. The greater value resulting from this comparison
must be used.
Figure 8: Representation of the accessibility of electro-sensitive protective device by reaching
over. Left: Protective field that cannot be reached over. Right: Protective field that can be
reached over.
8014253/YST2/2016-04-11 | SICK
Subject to change without notice