Leuze electronic MLC 520 EX Series - Calculation of Safety Distance S for Parallel Approach to the Protective Field

Mounting
Leuze electronic MLC 520 EX 24
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
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 pro-
tective 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
protective 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)
Calculation example
The danger zone in front of a machine with a stopping time of 140 ms is to be safeguarded as close to the
floor height as possible using a horizontal safety light curtain as a replacement for a PS mat. Installation
height H
min
can be = 0 - additional distance C to the safety distance is then 1200 mm. The shortest possible
safety sensor is to be used; the first value to be selected is to be 1350 mm.
The receiver with 40 mm of resolution and 1350 mm protective field height has a response time of 13 ms,
an additional MSI-SR4 relay interface a response time of 10 ms.
 Calculate safety distance S
RO
using the formula acc. to EN ISO 13855.
K [mm/s] = 1600
T [s] = (0.140 + 0.013 + 0.010)
C [mm] = 1200
S [mm] = 1600 mm/s  0.163 s + 1200 mm
S [mm]= 1461
The safety distance of 1350 mm is not sufficient; 1460 mm are necessary.
This is why the calculation is repeated with a protective field height of 1500 mm. The response time is now
14 ms.
 Re-calculate safety distance S
RO
using the formula acc. to EN ISO 13855.
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.
S
RO
KT C
RO
+=
SKTC+=
SKTC+=