Pagina 382 - GC_Sensor_Vision_Safety_Measurement-ENA4

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PHOTOELECTRIC DEVICES FOR SAFETY
Note: The reference Standard is the EN 999 / ISO 13855 ‘Safety of machinery - the positioning
of protective equipment in respect of approach speeds of parts of the human body’. The given
information is indicative and synthetic; it is compulsory to refer to the complete EN 999 / ISO 13855
standard for a correct safety distance calculation.
The minimum distance S in mm between the hazardous area and the detection point is expressed by
the formula:
S = (K x T) + C
K is a parameter (mm/sec) linked to the approach speed of the human body or parts
T is the total time (sec) necessary to stop the machine, where T = t 1 + t2
t1 = max. time between the detection actuation and the change of the device switching status
t2 = max. machine response time
C is an additional distance (mm) based on the device typology used in terms of resolution, where the
resolution is the minimum dimension of an opaque object able to obscure at least one of the beams of
the sensitive detection area.
Normal approach to the detection area
Safety light curtains with 40 mm maximum resolution
S = (K x T) + C
where K = 2000 mm/sec, C = 8 (d - 14 mm) but not smaller than 0,
d = device resolution (mm)
This formula is valid for safety distances S up to 500 mm.
If the result of the formula gives S higher than 500 mm, K = 1600 mm/sec
and S = (1600 mm/sec x T) + 8(d-14 mm)
Safety light curtains with 40 to 70 mm resolution
S = (K x T) + C
where K = 1600 mm/sec, C = 850 mm
In all cases, the highest beam height is ∅ 900 mm and the lowest beam is ≤ 300 mm.
Safety light grid with separate multiple beams
S = (K x T) + C
where K = 1600 mm/sec, C = 850 mm
Selection guide
opaque
object
R ≤ 40mm Finger or handprotection
R< 116 mm Presence detection
R > 70 mm Body protection R=resolution