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Multi-turn actuators
SA .1 with AC 01.2-22X/-22Y/ACExC 01.2-22X/-22Y
Information
9.2.
Specific figures for AC 01.2 actuator controls in 22X or 22Y version with actuators of the SA .1
type range
Information
The safety-related figures mentioned in this safety manual are only valid if all the
conditions stipulated in this safety manual and the mentioned activities are respected.
The PFD values specified in this safety manual are only examples and subject to
certain assumptions e.g. on T
The PFD calculation should always be performed individually for each system using
the parameters and conditions applicable for the respective system. The λ
λ
values should be used as input. When observing the proof test procedures indic-
DD
ated in this safety manual, we recommend using a proof test coverage (PTC) of 90
% for the calculations.
The following figure tables provide an example of safety figures for the different
versions. If one or several of the assumptions indicated below are changed, you
have to recalculate the probability of failure on demand in particular, but possibly
also other parameters.
When determining the PFD values, please note that the stipulated proof test cannot
fully restore the system. For this reason, the following data is used for calculation:
PTC = 90 % (proof test coverage rate [%])
T
= 1 year (proof test interval [h])
1
T
= 10 years (demand interval = lifetime [h])
2
MRT = 72 hours (mean repair time [h])
Td_ESD = 730 hours
(diagnostic test interval of actuator monitoring (for Safe ESD [h] safety function)
Td_ESD_AVG = 365 hours (mean duration for failure detection)
Td_STOP = 0 hours (diagnostic test interval [h])
Td_end_position = 730 hours
MTTR_ESD = 437 hours
MTTR_STOP = 72 hours
MTTR_end_position = 802 hours
The following formula can be used for the calculation of the PFD
The figures for Safe STOP OPEN or Safe STOP CLOSE, indicated in the subsequent
tables, refer to one of the two functions. If a general Safe STOP (inhibit operation in
both directions) is to be performed while activating the functions Safe STOP OPEN
and Safe STOP CLOSE at the same time, the double failure rate of the respective
individual functions (Safe STOP OPEN/CLOSE) must be applied for the assessment.
Table 11: SA .1/SAEx .1 type range with AC/ACExC 01.2 actuator controls in 22X/22Y
version
SA 25.1 – SA 40.1 / SAEx 25.1 – SAEx 40.1
Switchgear version: Contactors
Safety function
λ
S
1)
λ
DD
λ
DU
SFF
, MTTR, ...
proof
Safe ESD with PVST or RM
217 FIT
1,302 FIT
383 FIT
79.8 %
Safety-related figures
and
DU
values:
avg
Safe STOP OPEN or Safe
STOP CLOSE
1,106 FIT
176 FIT
392 FIT
76.5 %
41
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