BECKHOFF TwinSAFE - Manual (Page 46)

Circuit examples
44 Application Guide TwinSAFE
EL2904
Parameter Value
Current measurement active Yes
Output test pulses active Yes
2.7.2 Block formation and safety loops
2.7.2.1 Block 1
2.7.3 Calculation
2.7.3.1 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
2.7.3.2 Diagnostic Coverage DC
Component Value
S1 with plausibility DC
avg
=90%
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%
S1 EL1904 EL6900 EL2904
K1
K2
S2 EL1904