Siemens SINAMICS DCM - Evaluation of Respond; Evaluation of Respond with Two Power Switching Devices; Evaluation of Two 3 WL Circuit Breakers

Evaluation of the safety function according to EN 62061
11.3 Evaluation of "Respond"
Application document for functional safety STO, SS1 (ISO 13849-1)
66 Compact User Manual, 09/2016, A5E34871844AM
11.3
Evaluation of "Respond"
11.3.1
Evaluation of "Respond" with two power switching devices
11.3.1.1
Evaluation of two 3WL circuit breakers
Result
Result
Reason
SILCL
SIL claim limit
2 Hardware fault tolerance HFT=1
PFH
D
3.21 E-08
2-channel architecture with identical partial systems
Values to calculate the PFH
D
Parameter
Value
Reason
Definition
B10
B10 value 3WL circuit
breaker
7.5 * 10
3
Manufacturers data SIEMENS AG
Percentage of dangerous
failures
3WL circuit breaker
0.5 (50 %) Manufacturers data
T1
service life
175200 h Expected service life, 20 years
C
Number of times that the
3WL circuit breaker is
opened/closed
1 / 24 h Assumption:
The device is actuated once a day
The device can be actuated every day of the
year
User
T2
Diagnostic test interval
24 h It is actuated once a day.
A defective contact is detected.
CCF factor (β)
susceptibility to common-
cause failures
0.1 (10 %) When installed according to EN 62061, this can
assumed to be a "conservative value"
DC
Diagnostic Coverage
0.60 (60 %) Redundant switch off signal path where one of
the operating mechanism elements is moni-
tored.
(60 % worst case assumption; all relevant
switching states are incorporated in the feed-
back circuit of the evaluation unit. Incorrect
responses/behavior cannot be acknowledged.)