<A1. SAFETY INSTRUMENTED SYSTEMS INSTALLATION>
A1-8
IM 01R01B30-00E-E 8th edition November 01, 2019-00
All Rights Reserved. Copyright © 2003, Rota Yokogawa
Table A1-7: Summary for RAKD ([V3]) with standard limit switches
7
– Failure rate
Profile 3
Fail Safe Detected (
λ
SD)
0 FIT
Fail Safe Undetected (
λ
SU)
81 FIT
Fail Dangerous Detected (
λ
DD)
4 FIT
Fail Dangerous Undetected (
λ
DU)
203 FIT
SFF
4
29 %
MTBF
226 years
SIL AC
5
SIL1
Safety metrics according to ISO 13849-1
6
:
MTTF
d
(years)
551
DC
2 %
Category (CAT)
CAT 1
Performance Level (required)
PL
r
= c
Performance Level (calculated)
2.07E-07 1/h
T[Proof] = 1 year
T[Proof] = 5 years
T[Proof] = 10 years
PFDAVG = 9.69E-04
PFDAVG = 4.49E-03
PFDAVG = 8.89E-03
3
The switching contact output is connected to a "fail-safe" NAMUR amplifier. The failure rates of the
amplifier are not included in the listed failure rates
4
The complete sensor subsystem will need to be evaluated to determine the overall Safe Failure
Fraction. The number listed is for reference only.
5
SIL AC (architectural constraints) means that the calculated values are within the range for hardware
architectural constraints for the corresponding SIL but does not imply all related IEC 61508 requirements
are fulfilled.
6
Depending on the application and possible external diagnostics a higher DC
D
and therefore also a higher
category might be possible to achieve.
7
The switching contact output is connected to a "fail-safe switch" amplifier. The failure rates of the amplifier
are not included in the listed failure rates.