Leuze electronic MLC 520 - Minimum distance to reflective surfaces

Mounting
Leuze electronic MLC 520 25
Calculation example
The danger zone in front of a machine with a stopping time of 140ms is to be safeguarded as close to the
floor height as possible using a horizontal safety light curtain as a replacement for a PS mat. Installation
heightH
min
can be=0 - additional distanceC to the safety distance is then 1200mm. The shortest possible
safety sensor is to be used; the first value to be selected is to be 1350mm.
The receiver with 40mm of resolution and 1350mm protective field height has a response time of 13ms,
an additional relay interface a response time of 10ms.
Ä Calculate safety distanceS
RO
using the formula acc. to ENISO13855.
K [mm/s] = 1600
T [s] = (0.140+0.013+0.010)
C [mm] = 1200
S [mm] = 1600mm/s×0.163s+1200mm
S [mm] = 1461
The safety distance of 1350mm is not sufficient; 1460mm are necessary.
This is why the calculation is repeated with a protective field height of 1500mm. The response time is now
14ms.
Ä Re-calculate safety distanceS
RO
using the formula acc. to ENISO13855.
K [mm/s] = 1600
T [s] = (0.140+0.014+0.010)
C [mm] = 1200
S [mm] = 1600mm/s×0.164s+1200mm
S [mm] = 1463
A suitable safety sensor has been found; its protective field height is 1500mm.
6.1.4 Minimum distance to reflective surfaces
WARNING
Failure to maintain minimum distances to reflective surfaces may result in serious injury!
Reflective surfaces can indirectly deflect the transmitter beams to the receiver. In this case, in-
terruption of the protective field is not detected.
Ä Determine the minimum distancea (see figure below).
Ä Make certain that all reflective surfaces are the necessary minimum distance away from the
protective field according to prENIEC61496-2 (see the following diagram “Minimum dis-
tance to reflective surfaces as a function of the protective field width”).
Ä Check that reflective surfaces do not impair the detection capability of the safety sensor be-
fore start-up and at appropriate intervals.
a
b
4°
4°
c
a Required minimum distance to reflective surfaces [mm]
b Protective field width [m]