Application manual for YRB-4EML-31S safety relay
Contrinex AG Industrial Electronics
11
S1
2.2.2
Determination of the required performance level (PL
r
)
The PL
r
is determined in combination with the safety function within the framework of the
higher-level risk assessment. For each safety function, the required PL
r
is estimated using
the risk graph below.
Low risk
Start
P1
F1
S1
P2
P1
F2
P2
P1
F1
P2
P1
F2
P2
a
b
Required
c
performance
level
d
e
High risk
Figure 2
Risk graph (according to EN 13849-1)
Meaning of individual parameters:
S: severity of injury
S1
Slight (normally reversible) injury
S2
Serious (normally irreversible) injury
F: frequency and duration of exposure to the hazard
F1
Seldom to not very frequent or exposure to hazard is brief
F2
Frequent to continuous or exposure to hazard is long
P: possibility of avoiding or limiting damage
P1
Possible under specific conditions
P2
Scarcely possible
2.2.3
Technical implementation
This step involves the technical pre-planning of the safety function, taking possible
technologies and components into account. The safety-related components and parts must
then be identified for later verification.