Leuze electronic MLC 500 - Safety distance calculations (orthogonal & parallel)

Mounting
Leuze electronic MLC 520 Host/Guest 23
NOTICE
If longer stopping times are determined during regular inspections, an appropriate additional
time must be added to t
m
.
6.1.2 Calculation of safety distance if protective fields act orthogonally to the approach direction
With vertical protective fields, ISO13855 differentiates between
• S
RT
: safety distance concerning access through the protective field
• S
RO
: safety distance concerning access over the protective field
The two values are distinguished by the way additional distanceC is determined:
• C
RT
: from a calculation formula or as a constant (see chapter 6.1.1 "Calculation of safety distanceS")
• C
RO
: from the following table “Reaching over the vertical protective field of electro-sensitive protective
equipment (excerpt from ISO13855)”
The larger of the two values S
RT
and S
RO
is to be used.
Calculation of safety distanceS
RT
acc. to ISO13855 when access occurs through the protective
field:
Calculation of safety distanceS
RT
for point of operation guarding
S
RT
[mm] = Safety distance
K [mm/s] = Approach speed for point of operation guarding with approach reaction and normal approach di-
rection to the protective field (resolution 14to40mm): 2000mm/s or 1600mm/s, when
S
RT
>500mm
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
RT
[mm] = Additional distance for point of operation guarding with approach reaction with resolutions of
14to40mm, d=resolution of protective device C
RT
=8×(d-14)mm
Calculation example
The feeding-in area in a press with a stopping time (including press Safety PLC) of 190ms is to be safe-
guarded with a safety light curtain with 20mm of resolution and 1200mm of protective field height. The
safety light curtain has a response time of 22ms.
Ä Calculate safety distanceS
RT
using the formula acc. to ISO13855.
K [mm/s] = 2000
T [s] = (0.022+0.190)
C
RT
[mm] = 8×(20-14)
S
RT
[mm] = 2000mm/s×0.212s+48mm
S
RT
[mm] = 472
S
RT
is smaller than 500mm; this is why the calculation may not be repeated with 1600mm/s.
NOTICE
Implement the stepping behind protection required here, e.g., through the use of an additional or
cascaded safety sensor for area protection.