2 block formation and safety loops, 3 calculation – BECKHOFF TwinSAFE User Manual
Page 40
![background image](/files/774887/content/doc040.png)
Circuit examples
38
Application Guide TwinSAFE
EL2904
Parameter
Value
Current measurement active
No
Output test pulses active
No
2.6.2
Block formation and safety loops
2.6.2.1
Block 1
2.6.3
Calculation
2.6.3.1
PFH / MTTF
d
/B10
d
– values
Component
Value
EL1904 – PFH
1.11E-09
EL2904 – PFH
1.25E-09
EL6900 – PFH
1.03E-09
S1 – B10
d
100,000
S2 – B10
d
10,000,000
K1 – B10
d
1,300,000
K2 – B10
d
1,300,000
Days of operation (d
op
)
230
Hours of operation / day (h
op
)
16
Cycle time (minutes) (T
cycle
)
10080 (1x per week)
Lifetime (T1)
20 years = 175200 hours
2.6.3.2
Diagnostic Coverage DC
Component
Value
S1 with testing/plausibility
DC
avg
=99%
S2 with plausibility
DC
avg
=90%
K1/K2 without testing and with EDM via a safe
input
DC
avg
=90%
S1
EL1904
EL6900
EL2904
K1
K2
S2
EL1904