BECKHOFF TwinSAFE - Manual (Page 112)

Circuit examples
110 Application Guide TwinSAFE
Inserting the values, this produces:
S1:
݊
௢௣
ൌ
230 כ 8 כ 60
15
ൌ 7360
ܯܶܶܨ
ௗ
ൌ
1000000
0.1 כ 7360 ൌ 1358.7y ൌ 11902174h
S2:
݊
௢௣
ൌ
230 כ 8 כ 60
15
ൌ 7360
ܯܶܶܨ
ௗ
ൌ
2000000
0.1 כ 7360 ൌ 2717.4y ൌ 23804424h
K1/K2:
݊
௢௣
ൌ
230 כ 8 כ 60
15
ൌ 7360
ܯܶܶܨ
ௗ
ൌ
1300000
0.1 כ 7360 ൌ 1766.3y ൌ 15472788h
and the assumption that S1, S2, K1 and K2 are in each case single-channel:
ܯܶܶܨ
ௗ
ൌ
1
ߣ
ௗ
results in a
ܲܨܪ ൌ
0.1 כ ݊
௢௣
כ ሺ1 െ ܦܥሻ
ܤ10
ௗ
ൌ
1 െ DC
MTTF
ୢ
S1:
ܲܨܪ ൌ
1 െ 0.99
1358.7 כ 8760
ൌ 8.40E െ 10
S2:
ܲܨܪ ൌ
1 െ 0.99
2717.4 כ 8760
ൌ 4.20E െ 10
K1/K2:
ܲܨܪ ൌ
1 െ 0.99
1766.3 כ 8760
ൌ 6.46E െ 10