Mttf, ܯܶܶܨ, כ 8760 – BECKHOFF TwinSAFE User Manual
Page 55
Circuit examples
Application Guide TwinSAFE
53
Hence:
ܯܶܶܨ
ௗ
ሺEL1904ሻ ൌ
൫1 െ ܦܥሺܧܮ1904ሻ൯
ܲܨܪሺܧܮ1904ሻ
ൌ
ሺ1 െ 0.99ሻ
1.11E െ 09
ଵ
୦
כ 8760
୦
୷
ൌ
0.01
9.72E െ 06
ଵ
୷
ൌ 1028.8y
ܯܶܶܨ
ௗ
ሺEL6900ሻ ൌ
ሺ1 െ ܦܥሺܧܮ6900ሻሻ
ܲܨܪሺܧܮ6900ሻ
ൌ
ሺ1 െ 0.99ሻ
1.03E െ 09
ଵ
୦
כ 8760
୦
୷
ൌ
0.01
9.02E െ 06
ଵ
୷
ൌ 1108.6y
ܯܶܶܨ
ௗ
ሺEL2904ሻ ൌ
ሺ1 െ ܦܥሺܧܮ2904ሻሻ
ܲܨܪሺܧܮ2904ሻ
ൌ
ሺ1 െ 0.99ሻ
1.25E െ 09
ଵ
୦
כ 8760
୦
୷
ൌ
0.01
1.1E െ 05
ଵ
୷
ൌ 913.2y
MTTF
d tot
=
ଵ
భ
లళవ.య
ା
భ
భబమఴ.ఴ
ା
భ
భభబఴ.ల
ା
భ
వభయ.మ
ା
భ
ఴఴయ.మ
ൌ 179.4ݕ
DC
avg
=
వవ%
లళవ.య
ା
వవ%
భయఱఴ.ళ
ା
వవ%
భబమఴ.ఴ
ା
వవ%
భభబఴ.ల
ା
వవ%
వభయ.మ
ା
వబ%
ఴఴయ.మ
ା
వబ%
ఴఴయ.మ
భ
లళవ.య
ା
భ
భయఱఴ.ళ
ା
భ
భబమఴ.ఴ
ା
భ
భభబఴ.ల
ା
భ
వభయ.మ
ା
భ
ఴఴయ.మ
ା
భ
ఴఴయ.మ
ൌ 96.26%
CAUTION
Measures for attaining category 3!
This structure is possible only up to category 3 at the most on account of a possible
sleeping error.
In order to attain category 3, all rising and falling edges must be
evaluated together with the time dependence in the controller for the feedback
expectation!
MTTF
d
Designation for each channel
Range for each channel
low
3 years
≤
MTTF
d
< 10 years
medium
10 years
≤
MTTF
d
< 30 years
high
30 years
≤
MTTF
d
≤
100 years
DC
avg
Designation
Range
none
DC < 60 %
low
60 %
≤
DC < 90 %
medium
90 %
≤
DC < 99 %
high
99 %
≤
DC