95
Numbers of beams Heights above reference plane (mm)
4
300, 600, 900, 1200
3
300, 700, 1100
2
400, 900
1.2 Positions of the beams above reference plane
1.4 Circumventing of ESPE by reaching over the detection zone
For light curtains with detection capability d <= 40 mm
, the equation used to calculate the minimum distance S from a
vertical detection zone hortogonal to the direction of approach to the hazard zone is:
S = K (T1 + T2) + C
Where C is an additional intrusion distance:
C = 8 (d -14) mm if resolution ≤ 40 mm
C = 850 mm if resolution > 40 mm
The equation must be first calculated using K = 2000 mm/s.
If the result S > 500 mm, it can be recalculated with K = 1600 mm/s.
The result S must in any case be:
S >= 100 mm if K = 2000 mm/s is used;
S >= 500 mm if K = 1600 mm/s is used
For light curtains with detection capability d >40mm and multiple separate beams (body detection)
the following values
can be used:
C = 850 mm
K = 1600 mm/s
When the safeguard is used only for the detection of whole body access:
a) the height of the lowest beam shall be ≤ 300 mm to prevent access under the detection zone
b) the height of the uppermost beam shall be
≥
900 mm to prevent stepping over the detection zone.
EN13855 states that the heights for 2, 3 and 4 beams given in the following table have been found to be the best
compromise between an adequate risk reduction and the most practical in application.
Further protective measures to prevent access to the hazard zone can be required. For the lowest beam 400 mm can
only be used when the risk assessment allows it.
If access to the hazard zone by reaching over the detection zone of vertically mounted electro-sensitive protective
equipment cannot be excluded, an additional distance must be applied, depending on the height of the hazard zone and
the height of upper edge of the ESPE detection zone. For reference, apply EN ISO 13855 Par. 6.5.
APPENDIX
