LinMot C1250 Series Installation Manual page 17

Installation Guide C1250
DC (Diagnostic Coverage) is high (99%) assuming that the state of the feedback contacts is checked
after each change of the state of the control contacts.
The MTTF mainly depends on the number of operations of the safety relays.
d
Example calculation of MTTF
Assuming that the safety function is requested every 20 s on a machine running 24 h per day and 7 days per
week.
B =
10
B =
10d
n =
op
MTTF =
d
=
NTI AG / LinMot
:
d
10'000'000
20'000'000 (according EN ISO 13849-1:2008 table C.1)
(24 h/day * 365.25 days/year * 3600 s/h) / 20 s = 1'577'880 operations per year
B / (0.1 * n ) = 126.75 years
10d op
(This has to be limited to 100 years according the standard for further calculations)
high (100 years)
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