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FMEA of the (close/open)
Circuit type B
Final Element
Type A
Electronic Control
Diagnostic Circuit
Type B
Combination
is Type B
Diagnostics can be internal or external as defined in clause
(part 2, 7.4.9.4)
Diagnostics Internal or external, its random hardware failures
assessment must be considered
Ed.2 says (part 2, clause 7.4.9.4-J) : The failure rate of the
diagnostics, due to random hardware failures should be
specified. Why? to enable the derivation of the safe failure
fraction (SFF) and DC of the element .