2 block formation and safety loops, 3 calculation – BECKHOFF TwinSAFE User Manual
Page 22
Circuit examples
20
Application Guide TwinSAFE
EL2904
Parameter
Value
Current measurement active
Yes
Output test pulses active
Yes
2.3.2
Block formation and safety loops
2.3.2.1
Block 1
2.3.3
Calculation
2.3.3.1
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
2.3.3.2
Diagnostic Coverage DC
Component
Value
S1 with testing/plausibility
DC
avg
=99%
K1/K2 with testing and EDM (actuation 1x per
week and indirect feedback)
DC
avg
=90%
K1/K2 with testing and EDM (actuation 1x per shift
and direct feedback)
DC
avg
=99%
2.3.3.3
Calculation for block 1
Calculation of the PFH and MTTF
d
values from the B10
d
values:
S1
EL1904
EL6900
EL2904
K1
K2