User Documentation

Safety parameters
12 1485620000/01/11.2017
8. Safety parameters
Safety parameter
Ex output SIL2
Proof-test interval (T
proof
), (10 % of loop PFD)
5 years
Safe Failure Fraction (SFF)
92 %
Demand response time, opto output
< 125 µs
Demand mode
High
Demand rate
1000 s
Diagnostic test interval
10 s
Mean Time To Repair (MTTR)
8 h
Hardware Fault Tolerance (HFT)
0
Component type
B
SIL capability
SIL 2
Description of the “safe state”, opto output
High impedance
PFD
AVG
PFH (see note 1)
T
proof
= 1 year
T
proof
= 2 years
T
proof
= 5 years
1.58 × 10
-4
3.17 × 10
-4
7.92 × 10
-4
3.62 × 10
-8
h
-1
PFD
AVG
= Average Probability of Failure on Demand
PFH = Probability of dangerous Failure per Hour
Note 1: The ACT20X-(2)HDI-(2)SDO contains no lifetime limiting components, therefore the PFH figures
are valid for up to 12 years, according to IEC 61508.