8540581 - 29/09/2010 - Rev.10
7
SAFETY DISTANCE CALCULATION
The barrier 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 European standard EN999, the minimum safety distance
S
must be calculated
using the following formula:
S = K (t
1
+ t
2
) + C
where:
S
minimum safety distance
mm
K
approach speed of object to the dangerous area
mm/sec
t
1
response time of the safety barrier in seconds
sec
t
2
machine response time, in seconds, meaning the time
required for the machine to interrupt the dangerous movement
following transmission of the stop signal
sec
c
additional distance
mm
The non-observance of the correct safety distance reduces or cancels the protective
action of the light curtain.
If the position of the barrier 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”=Safety distance
Figure 5
HAZARDOUS
MACHINE
S
