BECKHOFF TwinSAFE - Manual (Page 72)

Circuit examples
70 Application Guide TwinSAFE
2.11.3.2 Diagnostic Coverage DC
Component Value
S1 with testing DC
avg
=90%
S2 with testing and expectation DC
avg
=99%
Lock/unlock with testing/plausibility DC
avg
=99%
Restart DC
avg
=99%
K1/K2 with testing and EDM DC
avg
=99%
Tumbler DC
avg
=99%
2.11.3.3 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 ݊
௢௣
Inserting the values, this produces:
S1:
݊
௢௣
ൌ
230 כ 16 כ 60
15
ൌ 14720
ܯܶܶܨ
ௗ
ൌ
2000000
0.1 כ 14720
ൌ 1358.7y ൌ 11902174h
S2:
݊
௢௣
ൌ
230 כ 16 כ 60
15
ൌ 14720
ܯܶܶܨ
ௗ
ൌ
2000000
0.1 כ 14720
ൌ 1358.7y ൌ 11902174h
Lock/Unlock:
݊
௢௣
ൌ
230 כ 16 כ 60
15
ൌ 14720
ܯܶܶܨ
ௗ
ൌ
100000
0.1 כ 14720
ൌ 67.9y ൌ 595108h
K1/K2:
݊
௢௣
ൌ
230 כ 16 כ 60
10080
ൌ 21.90
ܯܶܶܨ
ௗ
ൌ
1300000
0.1 כ 21.90
ൌ 883.2y ൌ 7736413h