Beckhoff EL72 1-901 Series Manual page 183

Integrated safety
Calculation for block 1
Calculation of the PFH and MTTF values from the B10 values:
d d
From:
and:
Inserting the values, this produces:
S1:
S2:
and the assumption that S1 and S2 are each single-channel:
produces for
S1:
S2:
EL72x1-901x Version: 1.9 183