SG-BWS-T4
8
3.4.
Minimum installation distance
The safety device must be positioned at a specific safety distance. This distance must ensure that the
dangerous area cannot be reached before the dangerous motion of the machine has been stopped by
the ESPE.
The safety distance depends on 4 factors, according to the EN 13855 Safety Norm:
Response time of the ESPE (the time between the effective sensors beam interruption and the
opening of the SAFCN contacts).
Machine stopping time (the time between the effective opening of the contacts of the ESPE
and the real stop of the dangerous motion of the machine).
ESPE resolution.
Approaching speed of the object to be detected.
S
Fig. 5 Safety Distance
The following formula is used for the calculation of the safety distance:
S = K (t
1
+ t
2
+ t
3
) + C
where:
S
=
Minimum safety distance in mm
K
(1)
=
Speed of the object, limb or body approaching the dangerous area in mm/s
t
1
=
SG-BWS-T4 response time in seconds (0.029)
t
2
=
The higher response time of all times for the safety sensors connected to SG-BWS-T4
t
3
=
Machine stopping time in seconds
d
=
Resolution of the system.
C
(2)
=
Additional distance based on the possibility to insert the body or one of body parts inside the dangerous area
before the protective device trips.
(1) K is:
1600 mm/s
(2) C is:
850mm for multibeam protections
1200mm for single optics systems
With multibeam light curtains, beam height from the ground must comply with the following chart:
4 beams
3 beams
2 beams
1 beam
Beams
height (mm)
1st
300
300
400
750
2nd
600
700
900
3rd
900
1100
4th
1200
Tab. 4 Beams height for photocells protections
