Performance Level (PL)
The standard IEC 13849-1 defines five performance levels (PL) for safety functions.
Level a is the lowest level and e is the highest.
Five levels (a, b, c, d, and e) correspond to different values of average probability of dangerous failure* per hour.
|
Performance Level |
Probability of a Dangerous Failure* per Hour |
|---|---|
|
e |
≥ 10-8 to < 10-7 |
|
d |
≥ 10-7 to < 10-6 |
|
c |
≥ 10-6 to < 3 x 10-6 |
|
b |
≥ 3 x 10-6 to < 10-5 |
|
a |
≥ 10-5 to < 10-4 |