Beckhoff TwinSAFE User Manual download pdf (Page 26)

Circuit examples

Application Guide TwinSAFE

MTTF

Designation for each channel

Range for each channel

low

3 years ≤ MTTF

< 10 years

medium

10 years ≤ MTTF

< 30 years

high

30 years ≤ MTTF

≤ 100 years

avg

Designation

Range

none

DC < 60 %

low

60 % ≤ DC < 90 %

medium

90 % ≤ DC < 99 %

high

99 % ≤ DC

For practical usability, the number of the ranges was limited to four. An accuracy of 5% is assumed for the limit

values shown in this table.

Category

1 2 2 3 3 4

MTTF

none none low medium low medium high

low

b b c -

medium

b - b c c d -

high

- c c d d d e

1 2 ... 21 22 23 24 25 26 27 28 29 30 31 ... 139 140

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Beckhoff TwinSAFE User Manual Page 26