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Contrinex Industrial Electronics
EN/ISO 13855 defines a basic formula for calculating the minimum
safety clearance between the protective device and the hazardous lo-
cation:
S = (K x T) + C
Parameters:
S: Minimum safety distance between the AOPD sensing field and
the hazardous area (mm). Cannot be less than 100 mm.
K: Average approach speed at which a body or part of a body en-
ters the detection zone (mm/s).
T: Total response time (seconds), including
T
c
: Response time of the protective device (in seconds,
value provided on manufacturer’s data sheet)
T
r
: Response time of the safety relay (in seconds, value
provided on manufacturer’s data sheet)
T
m
: Machine stopping time (in seconds, value provided by
manufacturer or measured on request by specialists)
C: Additional safety distance in mm, which depends on the resolu-
tion of the protective device. It cannot be less than zero.
R = Resolution of the protective device (mm)
C = 8 x (R -14 mm) where R
≤
40 mm (= 0 when the light curtain
has a resolution of 14 mm)
C = 850 mm where 40 mm
<
R
≤
70 mm
For a detection resolution
≤
40 mm, the formula thus becomes:
S = K x (T
c
+ T
r
+ T
m
) + 8 x (R -14 mm)
for a detection resolution 40 mm < R
≤
70 mm :
S = K x (T
c
+ T
r
+ T
m
) + 850 mm
where
K = 2000 mm/s *
* if the calculated value of S is
>
500 mm, then recalculate S using
K = 1600 mm/s
The above calculation formula applies when the protective device is
positioned vertically (perpendicular approach) or in case of an angular
approach if the angle (
b
) between the protective field and the direction
of entry exceeds 30
°
. S is then the distance from the hazardous point to
the closest protective beam.
In the case of horizontal positioning of the protective device (parallel
approach) or if the angle between the protective field and the direction
of entry is less than 30
°
, the applicable formula is:
