Siemens SINAMICS DCM - Evaluation of Two Power Contactors Connected in Series

Evaluating the safety functions according to EN ISO 13849 when using two switching devices
10.3 Evaluation of "Respond"
Application document for functional safety STO, SS1 (ISO 13849-1)
Compact User Manual, 09/2016, A5E34871844AM
59
10.3.1.2
Evaluation of two power contactors connected in series
Result, power contactor redundant
Result
Reason
PL
d The values for determination are listed in the following ta-
bles.
PFH
D
Average probability of a dangerous
failure per hour
9.06E-10
Determination of the PL power contactor
Parameter
Value
Reason
MTTF
D
of each channel
High MTTF
D
> 30 years (1,563.77 years)
DC
High DC = 99 %
direct monitoring using mirror contacts
Measures against CCF
Fulfilled It is assumed that the user has taken the necessary
measures.
Category
4 System response: One single failure does not result in the
loss of the safety function.
Calculation of MTTF
D
power contactor
Parameter
Value
Reason
Definition
B10
B10 value power contactor
1 * 10
6
Manufacturers data
SIEMENS AG
Percentage of dangerous failures
EMERGENCY STOP command device
0.73 (73 %) Manufacturers data
d
op
average operating time in days per year
365 days per year
Assumption:
The device can be actuated every
day of the year
User
h
op
average operating time in hours per day
24 hours per day
t
cycle
average time between the start of two con-
secutive cycles of the component
24 hours per cycle Assumption:
there is one day between actuating
the EMERGENCY STOP (testing
the EMERGENCY STOP)