BECKHOFF TwinSAFE - Manual (Page 71)

Circuit examples
Application Guide TwinSAFE 69
EL2904 (applies to all EL2904 used)
Parameter Value
Current measurement active Yes
Output test pulses active Yes
2.11.2 Block formation and safety loops
2.11.2.1 Block 1
2.11.3 Calculation
2.11.3.1 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
2,000,000
S2 – B10
d
2,000,000
Restart - B10
d 10,000,000
Lock – B10
d
100,000
Unlock – B10
d
100,000
K1 – B10
d
1,300,000
K2 – B10
d
1,300,000
Tumbler – B10
d
2,000,000
Days of operation (d
op
) 230
Hours of operation / day (h
op
) 16
Cycle time (minutes) (T
cycle
) 15 (4x per hour)
Lifetime (T1) 20 years = 175200 hours
EL1904 Restart
S1
S2
Lock
UnLock
EL2904 tumbler
EL1904 EL6900
K1
K2
EL2904