2 block formation and safety loops, 3 calculation, כ 60 – BECKHOFF TwinSAFE User Manual
Page 111: ܯܶܶܨ
Circuit examples
Application Guide TwinSAFE
109
2.18.2 Block formation and safety loops
2.18.2.1 Block 1
2.18.3 Calculation
2.18.3.1 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
1,000,000
S2 – B10
d
2,000,000
K1 – B10
d
1,300,000
K2 – B10
d
1,300,000
Days of operation (d
op
)
230
Hours of operation / day (h
op
)
8
Cycle time (minutes) (T
cycle
)
15 (4x per hour)
Lifetime (T1)
20 years = 175200 hours
2.18.3.2 Diagnostic Coverage DC
Component
Value
S1/S2 with testing/plausibility
DC
avg
=99%
K1/K2 with testing and EDM
DC
avg
=99%
2.18.3.3 Calculation for block 1
Calculation of the PFH and MTTF
d
values from the B10
d
values:
From:
݊
ൌ
݀
כ ݄
כ 60
ܶ
௬
and:
ܯܶܶܨ
ௗ
ൌ
ܤ10
ௗ
0.1 כ ݊
K1
K2
EL1904
EL6900
EL2904
S1
S2
K1
K2
EL1904
EL6900
EL2904
S1
S2
EL1904