User Documentation

Safety parameters
12 1485600000/01/11.2017
8. Safety parameters
Safety parameter
Ex output SIL2
Proof-test interval (T
proof
), (10 % of loop PFD)
4 years
Safe Failure Fraction (SFF)
90 %
Demand response time, relay output
< 10 ms
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”, relay output
de-energized
Relay lifetime (see note 1)
100000 times
Note 1: The maximum frequency for the pulse isolator with relay output is 20 Hz. The user must calcu-
late the product lifetime with regard to the relay lifetime.
PFD
AVG
PFH (see note 1)
T
proof
= 1 year
T
proof
= 2 years
T
proof
= 5 years
2.04 × 10
-4
4.08 × 10
-4
1.02 × 10
-4
4.66 × 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-RNx contains no lifetime limiting components, therefore the PFH
figures are valid for up to 12 years, according to IEC 61508.