turck 100030003, Руководство по безопасности

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7
V01.00 | 2021/10
4.3 PFH: Probability of dangerous failure per hour (High Demand mode)
A
SIL2
is specified.
In the following table 3 from 7.6.2.9 EN 61508-1:2010 is a PFH of less than 10
-6
h
-1
required.
A failure limit of 1 FIT corresponds to a PFH of 10 -9 h -1 .
Table 3 from 7.6.2.9 EN 61508-1
Safety Integrity
Level (SIL) Probablity of dangerous Failure per Hour from the safety function [h -1 ] (PFH)
4 ≥ 10 -9 … < 10 -8
3 ≥ 10 -8 … < 10 -7
2 ≥ 10 -7 … < 10 -6
1 ≥ 10 -6 … < 10 -5
In the safety chain, the device is granted a share of 10% of the respective failure limit value.
10%
100%
IM Actuator Sensor
This means that the failure limit value must be less than or equal 100 FIT.
(PFH <= 10 -7 h -1 )
4.4 PFD: Average probability of dangerous failure on demand (Low Demand mode)
A
SIL2
is specified.
In the following table 2 from 7.6.2.9 EN 61508-1:2010 is a PFD
avg
of less than 10
-2
h
-1
required.
Table 2 from 7.6.2.9 EN 61508-1
Safety Integrity
Level (SIL) Average probability of a dangerous failure when the safety function is requested
(PFD
avg
)
4 ≥ 10 -5 … < 10 -4
3 ≥ 10 -4 … < 10 -3
2 ≥ 10 -3 … < 10 -2
1 ≥ 10 -2 … < 10 -1
In the safety chain, the device is granted a share of 10 % of the respective failure limit value.