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9 Cabinet Design and EMC
9.4 Application examples
Determining
MTTF
d
9-358
An accumulation of faults between two consecutive actuations of the EMER-
GENCY STOP pushbutton is not detected:
S
Basic as well as well–proven safety principles – such as the requirements
regarding Category B – are maintained. Protective circuits are provided.
S
When a component fails, the safety function is always maintained.
The failure is detected.
This structure corresponds to Category 3, according to EN 13849–1:2008.
Table 9-7
Determining MTTF
Parameter
Value
Channel 1
Safety relay –K1 on the control module
B
value
20.000.000
10d
n
12 pro Jahr
op
MTTF
(–K1)
16.666.666 years
d
→ capped to
100 years
Channel 2
Line contactor –K2 in the line infeed
B
value
1.333.333
10d
n
12 pro Jahr
op
MTTF
(–K2)
1.111.111 years
d
→ capped to
100 years
Intermediate results, RESPOND (channels 1 and 2)
100 Jahre →
MTTF
d
(REAGIEREN)
hoch
SIMODRIVE 611 Configuration Manual (PJU) – 02/2012 Edition
d
Comment
Manufacturer's data
12 actuations per year as a result of
EMERGENCY STOP
B
10d
MTTF
=
d
0,1 x n
op
Manufacturer's data
12 actuations per year as a result of
EMERGENCY STOP
B
10d
MTTF
=
d
0,1 x n
op
MTTF
values for both channels were capped at
d
100 years → it is not necessary to symmetrize
both channels
© Siemens AG 2012 All Rights Reserved
02.12
05.01
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