2 block formation and safety loops, 3 calculation, כ 60 – BECKHOFF TwinSAFE User Manual
Page 34
Circuit examples
32
Application Guide TwinSAFE
2.5.2
Block formation and safety loops
2.5.2.1
Block 1
2.5.3
Calculation
2.5.3.1
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
2.5.3.2
Diagnostic Coverage DC
Component
Value
S1 with testing/plausibility
DC
avg
=99%
S2 with plausibility
DC
avg
=90%
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%
2.5.3.3
Calculation for block 1
Calculation of the PFH and MTTF
d
values from the B10
d
values:
From:
݊
ൌ
݀
כ ݄
כ 60
ܶ
௬
and:
S1
EL1904
EL6900
EL2904
K1
K2
S2
EL1904