Leuze electronic MLC 500 - Calculation of Safety Distance S for Parallel Approach to the Protective Field

Mounting
Leuze electronic MLC 520 Host/Guest 27
Calculation example
The feeding-in area in a press with a stopping time of 130ms is to be safeguarded with a safety light cur-
tain with 20mm of resolution and 600mm of protective field height. The response time of the safety light
curtain is 12ms; the press Safety PLC has a response time of 40ms.
The safety sensor can be reached over. The upper edge of the protective field is located at a height of
1400mm; the point of operation is located at a height of 1000mm
Additional distanceC
RO
to the point of operation is 700mm (see table “Reaching over the vertical protective
field of electro-sensitive protective equipment (excerpt from ISO13855)”).
Ä Calculate safety distanceS
RO
using the formula acc. to ISO13855.
K [mm/s] = 2000
T [s] = (0.012+0.040+0.130)
C
RO
[mm] = 700
S
RO
[mm] = 2000mm/s×0.182s+700mm
S
RO
[mm] = 1064
S
RO
is larger than 500mm; this is why the calculation may be repeated with approach speed 1600mm/s:
K [mm/s] = 1600
T [s] = (0.012+0.040+0.130)
C
RO
[mm] = 700
S
RO
[mm] = 1600mm/s×0.182s+700mm
S
RO
[mm] = 992
NOTICE
Depending on the machine construction, stepping behind protection, e.g. using a second hori-
zontally arranged safety light curtain, is necessary. In most cases, it will be more appropriate to
choose a longer safety light curtain which makes the additional distanceC
RO
equal to 0.
6.1.3 Calculation of safety distanceS for parallel approach to the protective field
Calculation of safety distanceS for danger zone guarding
S [mm] = Safety distance
K [mm/s] = Approach speed for danger zone guarding with approach direction parallel to the protective field
(resolution up to 90mm): 1600mm/s
T [s] = Total time of the delay, sum from (t
a
+t
i
+t
m
)
t
a
[s] = Response time of the protective device
t
i
[s] = Response time of the safety relay
t
m
[s] = Stopping time of the machine
C [mm] = Additional distance for danger zone guarding with approach reaction H=height of the protec-
tive field, H
min
=minimum installation height permitted, but no smaller than0, d=resolution of
the protective device C=1200mm-0.4×H; H
min
=15×(d-50)