4.2
Safe distance from hazardous areas
4.2.1
Vertical light barrier protection of hazardous areas
(valid for up to 40 mm resolution)
The safe distance S is calculated as follows:
- K = Grabbing speed or approach speed
For the grabbing speed K, a speed of 2000 mm/s is preset. If the calculation
for S produces a value greater than 500 mm, the calculation can be repeated
with 1600mm/s if this does not lead to a value lower than 500 mm (S min >
100 mm)
- T = t1 + t2
t1 = Response time of the safety device
With ULVT light barriers, the response time of the safety device
t1 depends on the number of beams (refer to Table on page 13).
When using the ULVT with the optional safety switching units, the response time of the switchgears is added to t1:
For LSUW N1 Muting switchgear:
20 ms
For LSUW NSR 3-1K switchgear:
25 ms
For ULSG switchgear:
6 ms
- t2 = overrun period of the machine
The overrun period of the machine t2 must be specified by the machine manufacturer.
- C = 8 (d - 14 mm)
d = Definition of the safety device
(minimum detectable obstacle size)
The definition capacity d ( = 14 mm or 30mm) is specified on the nameplate of the ULVT light barrier,
for d =14mm => C=0,
for d= 30 0> C= 128mm
Calculation examples for the safe distance with vertical area protection using ULVT light barriers
(valid for up to 40 mm resolution)
Example 1:
Safety light curtain ULVT100/13, resolution d = 14mm,
overrun period t2 of the machine from 75 ms
S = 2000 mm/s x (0.075s + 0.006s)
S = 162 mm
Example 2:
Safety light curtain ULVT500/35, resolution D = 30mm, ULSG safety switchgear
Overrun period t2 of the machine from 75 ms
S = 2000 mm/s x (0.075s + 0.007s + 0.006s) +8 x (30mm-14mm)
S = 304 mm
4
Installation
- Safety distance
S = (K x T) + C
for S = 100 mm bis 500 mm:
for S > 500 mm:
S = (2000 mm / s . T) + C
S = (1600 mm / s . T) + C
The safe distance (S) between the accident-preventing light barrier and hazardous area must be big enough to ensure
that when the protective field is penetrated, the hazardous area cannot be accessed before the hazardous movement
has been ended.
In addition, it must be ensured that reaching over, under or around, or walking behind the protective field is prevented
by additional mechanical screening or further light barriers. To this end, please also refer to EN 999 / ISO 13855 and
other effective national and international safety regulations.
fig. 14/1 Vertical light barrier protection of hazardous areas
S
Nachlaufweg
der Maschine
Overrun
traverse of
the machine
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14
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