Siemens SIPART PS2 Sicherheitshandbuch Seite 21

As the Electro-pneumatic Positioner SIPART PS2 is supposed to be a proven-in-use device, an
assessment of the hardware with additional proven-in-use demonstration for the device and its
software was carried out. The proven-in-use investigation was based on field return data
collected and analyzed by SIEMENS AG, A&D PI TQ2. This data cannot cover the process
connection. The proven-in-use justification for the process connection still needs to be done by
the end-user.
According to the requirements of IEC 61511-1 First Edition 2003-01 section 11.4.4 and the
assessment described in section 5.1 the Type B Electro-pneumatic Positioner SIPART PS2 with
a hardware fault tolerance of 0 and a SFF of 60% to < 90% are considered to be suitable for
use in SIL 2 safety functions The decision on the usage of proven-in-use devices, however, is
always with the end-user.
The following tables show how the above stated requirements are fulfilled for the worst case
configuration listed in Table 1.
Table 2: Summary
Fail Safe Detected
Fail Safe Undetected
Fail Dangerous Detected
Fail Dangerous Undetected
No Effect
Annunciation Undetected
Not part
MTBF = MTTF + MTTR
Table 3: Summary
Table 4: Summary
The boxes marked in yellow (
allowed range for SIL 2 according to table 2 of IEC 61508-1 but do not fulfill the requirement to
not claim more than 20% of this range, i.e. to be better than or equal to 2,00E-03. The boxes
marked in green (
SIL 2 according to table 2 of IEC 61508-1 and table 3.1 of ANSI/ISA–84.01–1996 and do fulfill
the requirement to not claim more than 20% of this range, i.e. to be better than or equal to
2,00E-03.
© exida.com GmbH
Stephan Aschenbrenner
SIL-Sicherheitshandbuch
Betriebsanleitung, 06/2005, A5E00442120-01
for SIPART PS2 as single-acting shutdow
Failure categor y
for SIPART PS2 as single-acting shutdow
sd su
0 FIT 1013 FIT
for SIPART PS2 as single-acting shutdow
T[Proof] = 1 y ear
PF D = 7,94E-0 4
AV G
) mean that the calculated PFD
n module – Failure rates
n module – IEC 61508 failure rates
dd du
4 FIT 182 FIT
n module – PF D
T[Proof] = 5 y ears
PF D = 3,96E-0 3
AV G
) mean that the calculated PFD
values are within the allowed range for
AVG
siemens 04-12-06 r004 v1 r1.0.doc, April 11, 2005
A.2 Prüfbericht (Auszug)
Failure rates (in FIT)
90 years
SFF DC
S
84% 0%
values
AV G
T[Proof] = 10 y ears
PF D = 7,91E-0 3
AV G
values are within the
AVG
Anhang
0
919
4
182
93
1
76
DC
D
2%
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