Mounting
Leuze electronic
MLC 520 EX
21
tance for access guarding for resolutions > 40 mm: C
RT
= 850 mm (standard value for
arm length)
Calculation example
Access to a robot with a stopping time of 250 ms is to be safeguarded with a safety light curtain with 90 mm
of resolution and 1500 mm of protective field height whose response time is 6 ms. The safety light curtain
directly switches the contactors whose response time is contained in the 250 ms. An additional interface
therefore does not have to be taken into consideration.
Calculate safety distance S
RT
using the formula acc. to EN ISO 13855.
K
[mm/s]
= 1600
T
[s]
= (0.006 + 0.250)
C
RT
[mm]
= 850
S
RT
[mm]
= 1600 mm/s
0.256 s + 850 mm
S
RT
[mm]
= 1260
This safety distance is not available in the application. This is why a new calculation is done with a safety
light curtain with 40 mm of resolution (response time = 14 ms):
Re-calculate safety distance S
RT
using the formula acc. to EN ISO 13855.
K
[mm/s]
= 1600
T
[s]
= (0.014 + 0.250)
C
RT
[mm]
= 8
(40 - 14)
S
RT
[mm]
= 1600 mm/s
0.264 s + 208 mm
S
RT
[mm]
= 631
The safety light curtain with a 40 mm resolution is thus suitable for this application.
Calculation of safety distance S
Ro
acc. to EN ISO 13855 when protective field is accessed from above:
Calculation of safety distance S
Ro
for point of operation guarding
S
RO
[mm]
= Safety distance
K
[mm/s]
= Approach speed for point of operation guarding with approach reaction and normal ap
-
proach direction to the protective field (resolution 14 to 40 mm): 2000 mm/s or
1600 mm/s, when S
RO
> 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
RO
[mm]
= Additional distance in which a body part can move towards the protective device before
the protective device triggers: value (see table 6.1)
For the calculation with K = 2000 mm/s, safety distance S
RT
equals 736 mm. The adoption of ap
-
proach speed K = 1600 mm/s is therefore permitted.
S
RT
K T C
RT
+
=
S
RT
K T C
RT
+
=
S
RO
K T C
RO
+
=
