SAFETY DISTANCE CALCULATION
The light curtain must be installed at a distance that is greater than or equal to the minimum
safety distance S, so that a dangerous point can only be reached after all hazardous
machine movements have stopped (Figure 5).
According to EN 999, the minimum safety distance S must be calculated using the following
formula:
where:
S
K
t
1
t
required for the machine to interrupt the dangerous movement
2
C
The non-observance of the correct safety distance reduces or cancels the protective
action of the light curtain.
If the position of the light curtain does not prevent the operator from having access
to the dangerous area without being detected, additional mechanical guards must be
installed to complete the system.
S = K (t
minimum safety distance
approach speed of object to the dangerous area
response time of the safety light curtain in seconds
machine response time, in seconds, meaning the time
following transmission of the stop signal
additional distance
S
"S"=Safety distance
Figure 5
+ t
) + C
1
2
mm
mm/sec
sec
sec
mm
HAZARDOUS
MACHINE
7