Description
Required performance level (PLr)
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Required performance level (PLr)
It is necessary to determine the required performance level (PLr) for each
safety function. The required performance level for the previously described
safety function is determined from the risk graph defined by DIN EN ISO
13849-1.
The path through the risk graph depends on how "severity of injury (S)",
"frequency and/or exposure to danger (F)" and "possibility of avoiding the
damage (P)" are assessed. The level of each risk situation is categorised in
five levels from "a" to "e", the so-called Performance Level (PL). The
proportion of the control function to reduce the risk is low at Performance
Level "a" and high at PL "e".
Risk graph
Performance Level (PLr)
Safety function Required performance level (PLr)
Required performance level
against unexpected start-up of
the belt conveyor (PLr)
C
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